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Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Phytoliths of Amazonian grasses: diversity and applications Fitolitos de gramíneas amazónicas: Diversidad y aplicaciones Gaspar Morcote-Ríos1, Diego Giraldo-Cañas1,2 & Lauren Raz1

1Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogotá D. C., Colombia.

2Corresponding author: dagiraldoc@unal.edu.co.

Orcid id: 0000-0003-0212-7489.

Recibido: 01-10-2024

Aprobado: 06-01-2025

Publicado: 31-03-2025

Artículo de investigación

## Abstract

### seven subfamilies. We identified 12

broad morphotype categories with a

In the Poaceae, silica accumulates in total of 54 variants, partitioned into two idioblast cells in leaves and other organs, datasets: GSSCP and other silicified forming bodies called “grass silica short epidermal structures; UPGMA analyses cell phytoliths” (GSSCP). Epidermal were conducted to test for groupings cells and hairs can also accumulate at subfamily level in the separate and silica and are considered phytoliths combined datasets. We found diagnostic as well. The GSSCPs are particularly morphotypes at the genus or even well studied and can be diagnostic at species level in some cases, and also different taxonomic levels, including identified silicified epidermal cells in subfamily. This, and the fact that both archaeological and paleoecological phytoliths can persist in soils for millions samples; however, we found no clear of years, make them useful proxies pattern of morphotype distribution at to characterize plant assemblages in subfamily level, a result that contrasts paleoecological and archaeological with GSSCP surveys from other studies. Over the past decade we have regions. We reiterate calls for more been developing phytolith reference intensive regional sampling to elucidate collections of Amazonian taxa to aid patterns of variation in both GSSCP and in the identification of ancient plant other silicified epidermal structures in remains from this region. To create grasses.

a representative Amazonian grass

collection, we extracted phytoliths Key words: Amazonian archaeology; from 150 species (88% of Colombian Amazonian paleoecology; Neotropical Amazonian grasses) in 59 genera and grasses; phytolith morphotypes.

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## Resumen

### epidérmicas silicificadas en muestras

arqueológicas y paleoecológicas. No

En las gramíneas, el sílice se acumula obstante, no encontramos un claro patrón en idioblastos en las hojas y otras de la distribución de los morfotipos al estructuras, constituyendo cuerpos nivel de subfamilia, un resultado que denominados “fitolitos de sílice de contrasta con los hallazgos de GSSCP

gramíneas en células cortas” (GSSCP). para otras regiones. Así, hacemos Las células epidérmicas y los tricomas hincapié en la necesidad de adelantar también pueden acumular sílice y éstos más muestreos regionales, con el fin de también se consideran fitolitos. Los dilucidar los patrones de variación, tanto GSSCP están bien estudiados y pueden en GSSCP como en otras estructuras ser diagnósticos en diferentes niveles epidérmicas silicificadas en gramíneas.

taxonómicos, incluídas las subfamilias.

Esto y el hecho de que los fitolitos pueden Palabras clave: Arqueología

persistir en los suelos durante millones amazónica; gramíneas neotropicales; de años, hacen de éstos “proxies” morfotipos de fitolitos; paleoecología útiles para caracterizar arreglos amazónica.

vegetales en estudios paleoecológicos

y arqueológicos. Nosotros hemos Introduction desarrollado en la pasada década, Phytoliths are microscopic structures colecciones de referencia de fitolitos de composed of hydrated silica (SiO *

diferentes taxones amazónicos, con el

2

nH O) that accumulates in the tissues

objetivo de ayudar en la identificación

2

of diverse plant taxa as well as in some

de restos vegetales de esta región. Así, unicellular eukaryotes (Prychid et al. , para crear una colección representativa 2003). They are especially abundant in de gramíneas amazónicas, extrajimos commelinid monocots, and in grasses fitolitos de 150 especies (88% de las they form two distinct groups of gramíneas amazónicas colombianas), structures; the best described are the so-distribuidas en 59 géneros y siete called grass silica short cell phytoliths subfamilias.

Identificamos

doce (GSSCP), which are formed in idioblast

categorías de morfotipos de fitolitos con cells in horizontal or vertical arrays in un total de 54 variantes, divididos en the epidermis of leaves and other organs dos grupos de datos: Los GSSCP y otras (Piperno, 2006; Strömberg, 2018).

estructuras epidérmicas silicificadas. These present morphologies that are Empleamos análisis UPGMA con el fin often diagnostic at or below subfamily de probar las agrupaciones de los fitolitos level (Twiss, 1969; Piperno & Pearsall, a nivel de subfamilia, por separado 1998; Rudall et al. , 2014; Neumann et y también combinando conjuntos de al. , 2017). To date, research has focused datos. Encontramos morfotipos de mostly on GSSCPs, but other epidermal fitolitos diagnósticos a nivel de género, structures in grasses may also become y en algunos casos, a nivel de especie. completely filled with silica, including Asimismo, pudimos identificar células bulliform cells, stomata, hairs and

20

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas prickles. These are also considered to infer open habitats, which may in phytoliths in the broader sense (Zucol, turn be associated with changes in 1998, 2000) and Strömberg (2018) land use (in archaeological contexts) discusses their utility, when examined or changes in vegetation cover due to collectively in sediments, as a proxy to climate or other non-anthropic factors interpret environmental conditions of a (paleoecological contexts), while finer given study site. Both she and Piperno taxonomic resolution is often desireable (2006) emphasize that individually in other kinds of studies. For example, these structures are of little diagnostic grass phytoliths have been used to study value, but to date, most grass phytolith domestication of rice (Whang et al. , studies have focused on GSSCPs, while 1998; Zhao et al. , 1998; Hilbert et al. , other types of grass phytoliths have 2017) and wheat (Ball, 1999) and to received far less attention. Nevertheless, reconstruct ancient diets in hominids microscopic leaf epidermal characters and other vertebrate species (Strömberg, have long been recognized as being of 2006; Henry et al. , 2012).

taxonomic utility, (Prat, 1932; Ellis,

1979; Palmer & Tucker, 1981; Londoño In our region of interest, the Amazon,

& Kobayashi, 1991; Khan et al. , 2017), there are several active areas of research which suggests that grass epidermal for which phytoliths are providing phytoliths might be of greater utility relevant datasets. By comparing than is generally appreciated.

contemporary, archaeological and

paleoecological data, it should be

Because phytoliths can persist in possible to understand the extent of sediments for millions of years, they human impacts on the Amazon during can be used to address a great variety the last 10,000 years (Ferreira et al. , of research questions in paleoecological 2019; McMichael & Bush, 2019).

(reviewed in Strömberg, 2018) and Phytoliths can also inform studies of archaeological studies (reviewed in vegetation changes in deeper time, Piperno, 2006). Grass phytoliths are including the formation of the Amazon of particular interest because pollen is itself (Piperno, 1997; Hoorn et al. , 2017, homogeneous in the family, whereas 2022). The Poaceae component of the phytoliths are both abundant and highly vegetation is particularly valuable for diverse. Because GSSCP morphotypes interpreting changes at both local and are often diagnostic at subfamily level landscape scales.

(Piperno, 2006; Bremond et al. , 2008; Strömberg, 2018), they are particularly Contrary to popular perceptions, the useful in paleoenvironmental studies, Amazon is not a homogeneous tropical where being able to distinguish C from rain forest, but a patchwork of different 3

C grasses of the PACMAD clade permits vegetation and soil types (Richards, 4

inferences about ancient climates. A 1996) including granitic outcrops high ratio of grass to eudicot phytoliths and white sands associated with the at a given study site is generally used Guayana Shield, and grass diversity

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in the region is correspondingly grasses and test the hypothesis that complex: we calculate 452 species in phytoliths are diagnostic at subfamily seven subfamilies, including both C level in this particular biogeographic 3

and C taxa. Panicoideae is by far the context. We also present examples 4

most diverse subfamily in the Amazon, of grass phytoliths obtained from with about 2/3 of all species, including archaeological and paleoecological both C and C genera. Historically, sediments in the Amazon to highlight the 3

4

phytolith studies have focused more utility of silicified epidermal structures on temperate and subtropical grasses, (non GSSCPs) in this region.

which are predominantly C , however

3

in the lowland tropics, the C pathway Materials and methods 4

predominates, and because the panicoids Phytolith extraction from have been particularly undersampled, it is contemporary grass specimens. For the subfamily with the least well defined this study we evaluated phytoliths in phytolith morphotypes (Neumann et Amazonian grasses corresponding al. , 2017). Piperno & Pearsall (1998) to 7 subfamilies, 59 genera, and 150

surveyed phytoliths in approximately species (88% of Colombian Amazonian 200 species of Neotropical grasses, grasses), sampled from the National but only 15% were of Amazonian Colombian Herbarium (COL), following distribution, and the authors signaled confirmation of the determinations.

the need for increased regional sampling Complete voucher information for the and increased attention to microscopic specimens is included in Morcote-Ríos features that can be used to separate et al. (2015); we also prepared seven phytolith morphotypes. Cavalcante additional samples from four species, (1968) surveyed phytoliths in 25 grass including two new genera and one species from the Brazilian Amazon, and subfamily (Anomochlooideae) that hoped one day to produce a catalogue were not included in the previous work.

of phytoliths of Amazonian grasses. Voucher information for the newly Unfortunately he did not fulfill this wish, included COL samples is as follows: but we recently published an illustrated Oryza grandiglumis: Giraldo-Cañas catalogue of phytoliths of grasses from 3641 (leaf), Duque-Jaramillo 2025

the Colombian Amazon (Morcote- (leaf and spikelets); Oryza latifolia:

Ríos et al. , 2015). Nevertheless, some Cuatrecasas 10873 (leaf); Streptochaeta important taxa were excluded from spicata: Smith 1530 (leaf), Black 51-that study (native species of Oryza and 12891 (leaf); Streptogyna americana: Streptochaeta) and we did not assess Giraldo-Cañas 2590 (leaf). The study patterns in the taxonomic distribution of includes 22 species that were introduced the observed morphotypes.

and have become naturalized in the

In the present study, we describe the Amazon during the last 500 years.

diversity of phytolith morphotypes Fourteen of the specimens sampled were from across the spectrum of Amazonian from extralimital collections; these were

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Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas chosen in cases where the Amazonian a fine grain sediment. The samples specimens did not have enough material were then treated with 200 ml of 50%

for destructive sampling. Although the hydrogen peroxide to eliminate all specimens may have come from other organic matter. This action was repeated lowland regions (e.g. Dinebra panicea five times until the solution became and Leptochloa virgata), the species are clear, indicating digestion of the organic nevertheless part of the Amazonian grass matter. The samples were then subjected flora. This study considers a third of all to three rounds of centrifugation at 2000

Amazonian grasses and the sampling is rpm during 5 min., the first two rounds representative at genus and subfamily in 90% EtOH and the final round in levels, following the classification of distilled water in order to eliminate all Soreng et al. (2017). We followed the traces of the peroxide. The phytoliths protocols for phytolith extraction from were then extracted using zinc chloride contemporary herbarium material as (ZnCl ) with a density of 2.1, and 2

described in Morcote-Ríos et al. (2015). centrifuged at 500 rpm for 5 min. to In most cases, only leaf tissue was separate the light and heavy fractions.

sampled (always the last leaf before The light fraction containing the the inflorescence), but for culturally phytoliths was decanted into labelled important species such as maize, microtubes and then mounted onto guadua and sugar cane, culms and glass slides in triplicate. The phytoliths inflorescences were also included.

were identified via comparison with

the contemporary reference collection

## Phytolith extraction from

### of the Instituto de Ciencias Naturales

archaeological and paleoecological at Universidad Nacional de Colombia sediments. Phytoliths were recovered (ICN, 2019), and Morcote- Ríos et al.

from a sediment sampled collected at (2015).

the locality of La Sardina (Amazonas,

Colombia), associated with a Terra For both the contemporary and ancient Preta (Amazonian Dark Earth) site samples, description and photography with a chronology of 1000 years BP of the phytoliths were carried out using (Kalin-Arroyo, M. et al. , unpubl. data), a Nikon Eclipse 400 microscope and an and from a paleoecological sediment Omni VID LW Scientic digital camera.

sample collected from a riverbank at the Although the structures are represented locality of Santa Sofía 3-91 (Amazonas, here two-dimensionally, they were Colombia), of Miocene age, between observed and described from multiple 15 and 12 Ma (Hoorn, C., unpubl. focal planes. During image processing, data). The preparation of the sediment the following functions were applied in samples was adapted from the protocols Adobe Photoshop CS5: noise reduction, of Piperno (1988, 2006) and Pearsall autocontrast and automatic color (1989). A volume of 1 ml of compact adjustment. The terminology employed sediment from each sample was here for describing phytoliths and other manually ground with a mortar to obtain anatomical structures is based on Ellis

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(1979), Zucol (1992, 2000), Gallego & all the variants are presented in Fig. 1, Distel (2004), and Madella et al. (2005). which also includes brief descriptions in the caption. We have assigned letter

Cluster Analyses.

Homology names to the 54 variants and these assessment in grass phytoliths is were the morphotypes that were coded not straight forward (Rudall et al. , in the cluster analysis (below), but 2014) and definition of characters and several of the variants actually have character states remains subjective. subvariants (e.g. Fig. 1U, W, HH, PP, Given the nature of the data we chose a YY, ZZ). Within a highly variable group clustering method for pattern detection like U for example, all subvariants (Neumann et al. , 2017; Zucol, 1998, share the same basic geometry but 2000). Once the morphotypes were with subtle differences in degrees of described, they were coded as present or curvature/concavity. Had we chosen absent for all 150 species in the dataset. to elevate each subvariant, we could In order to detect patterns at subfamily have recognized as many as 95 variants.

level, we used UPGMA cluster analysis These are the sorts of subjective based on the Sørensen-Dice similarity decisions that make comparison among index (qualitative), implemented in the studies by different authors difficult, an PAST3 statistics package. We analyzed issue raised by Neumann et al. (2017). In a combined matrix of both GSSCP and this case we opted to reduce the number silicified epidermal structures following of categories to make comparisons Zucol (1998, 2000), and also partitioned easier. Consistent with other authors the data into two matrices (GSSCP only (Piperno & Pearsall, 1998; Neumann et and Silicified Epidermal Structures al. , 2017), we recognized variation in only), which were analyzed separately the length of the center or shaft (= shank under the same parameters.

of Neumann et al. , 2017) of bilobate Results

forms, and the presence of convexities

and/or concavities in the lobes, as well

Diversity of phytolith morphotypes as variations in the length and/or degree in contemporary Amazonian

of curvature of the edges in the other grasses. Across the entire sample of morphotypes.

150 Amazonian grass species, we Contrary to our expectations, we did not recognized 54 phytolith morphotypes recover clear patterns of morphotype that we grouped into 12 broad distribution at the subfamily level, with categories (Figs.1, 2, 3). These include two notable exceptions in Chloridoideae seven GSSCP categories with 32 and Pharoideae. See Cluster Analyses, variants and five categories of silicified below for more results at subfamily level epidermal structures with 22 variants. (Figs. 4, 5, 6). Nevertheless, we did The taxonomic distribution of the find diagnostic morphotypes for certain morphotypes is presented in Table 1 genera and species in the Amazon and the schematic 2-D illustrations of and these are detailed below. They

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Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas include both GSCCPs and silicified presented from left to right in Table epidermal structures and are listed here 1. Consult Fig. 1 for illustrations and in order of the categories as they are descriptions of the diagnostic variants.

Figure 1.

Bilobate short cell (A-I). A, convex ends. Longest axis: 11.7-17.1 µm. E, ends. Longest axis: 9.8-21.5 µm. B, concave ends and rome projection.

concave ends. Longest axis: 5.8-31.3 Longest axis: 24.5 µm. F, Bilobate with µm. C, convex-concave ends. Longest short center and convex ends. Longest axis: 15.6-24.5 µm. D, straight-concave axis: 17.6-19.6 µm. G, concave ends and

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thick center; “thick cross” of Piperno 22 µm. KK, longest axis: 24-52 µm.

& Pearsall (1998). Longest axis: 10.7- LL, longest axis: 36 µm. MM, longest 15.6 µm. H, quadrangular. Longest axis: 45 µm. Elongate epidermal cell axis: 11.7 µm. I, acute projections and (NN-VV). NN, longest axis: 11.2-convex ends. Longest axis: 19.6-22.5 15.5 µm. OO, long, thick epidermal µm. Bilobate long cell (J-N). J, convex cell with one or few acute projections ends. 20.5-41.4 µm. K, concave ends. along one margin: Longest axis: 20-Longest axis: 17-45.6 µm. L, straight- 36 µm. PP, long, thick epidermal cells concave ends. Longest axis: 16.6-23.5 with serrate and/or ondulate margins.

µm. M, convex-concave ends. Longest Longest axis: 11.7-50.9 µm. QQ, long, axis: 20.5-24.5 µm. N, straight- convex thick epidermal cells with serrate and/

ends. Longest axis: 18.6-19.6 µm. or ondulate margins and ends rounded, Polylobate (O-Q). O, longest axis: the structure symmetrical. Longest axis: 22.5-53.9 µm. P, longest axis: 17.6- 115.2 µm. RR, long, thin epidermal 45.6 µm. Q, longest axis. 25.4-29.4 cell with straight margins with simple µm. Trapezoidal (R-Y). R, longest or double walls. Longest axis: 37.2-98

axis: 39.2 µm. S, longest axis: 9.8-48 µm. SS, silicified vessel element with µm. T, longest axis: 22.5-48 µm. U, parallel divisions. Longest axis: 20.5-trapezoidal concave base. Long. Base: 96 µm. TT, long epidermal cell with 3.4-23.5 µm. V, longest axis: 11.7 µm y concave end. Longest axis: 120 µm.

15 µm. W, trapezoidal flat base. Long. UU, elongated epidermal cell with acute Base: 10.7 µm and 24.5 µm. X, longest marginal projection aguda. Longest axis: axis: 11.7-27.4 µm. Y, trapeziform 16-144 µm. VV, rhomboid epidermical with sinuate base and double peaks. cell. Longest axis: 60 µm. Amorphous Longest axis: 42.1 µm. Height: 19.6 with marginal projections (WW-µm. Z, cross. Longest axis: 14 µm. XX). WW, amorphous with marginal Suborbicular-rectangular (AA-DD). projections. Longest axis: 36-40.1

AA, suborbicular with concave area. µm. XX, amorphous with short Longest axis. 10.7 µm. BB, rectangular acute projections on the surface, with two opposite sides concave and characterized by relatively small size, the others convex (Saddle). CC, longest with variable shapes, found exclusively axis. 9.8 µm. DD, longest axis: 13 µm. in the spikelets. Longest axis: 10.78-Carinate. EE, different views. Presents 23 µm. Misc. epidermal structures several acute projections in lateral (YY-ZZ). YY, elliptical stomatal view. Caracterized by carinate (crest- complexes. Longest axis: 18.1-48

like) structures. Present in very few µm. ZZ, bicellular microhair: Longest species, but at especially high density in axis: 19.6-98.4 µm. Epidermal prickle.

Trichanthecium polycomun. Bulliform Longest axis: 14.7-76.8 µm Trichomes: Cell. (FF-MM). FF, longest axis: 24.5 Longest axis: 21.5 µm, Unicellular µm. GG, longest axis: 48 µm. HH, macrohair: Longest axis 30.3-79.2 µm.

longest axis: 24.5-52.8 µm. II, longest AAA, Mammiform-Conical. Apex axis: 39.2-69.6 µm. JJ, longest axis: suborbicular. Base length: 7.4-18.6 µm.

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Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas

-In the GSCCP category bilobate short was also described in Pharus by Piperno cell, variant I was found exclusively (1988, 1998), who remarked at the time in Oryza latifolia (Fig. 2E). It is that it was an unusual morphotype characterized by having acute central for a bambusoid grass. In subsequent projections and concave lobes and classifications, Pharus has been placed is present at high density in this in its own subfamily, and this unique species. In the same category, variant phytolith morphotype could thus be E was found exclusively in Paspalum interpreted as an autapomorphy.

melanospermum and Ocellochloa

pulchella.

-We created a GSCCP category

carinate, with a geometry that does

-In the GSSCP category trapeziform, the not fit neatly in any of the established variant Y was found only in the spikelets categories but is characterized by the of Oryza grandiglumis and variant presence of notorious parallel ridges.

T is found only in the bambusoids This morphotype was observed in Olyra latifolia, and the genera Piresia, Ocellochloa stolonifera, Otachyrium Pariana, and Streptochaeta spicata versicolor, Streptochaeta spicata and (Anomochlooideae), while variant V the genus Trichanthecium. In S. spicata occurs exclusively in the genus Pariana. it is the most abundant morphotype, and previous authors have described it as

-In the GSCCP category cross, we saddle-like (Piperno & Pearsall, 1998) identified the unique variant Z in Piresia or irregular (Rudall et al. , 2014).

goeldii, characterized by its unusual thickness.

-Elongate epidermal cells of variant UU

were found exclusively in the culms

-In the GSSCP category suborbicular- (cane) of Saccharum officinarum, rectangular, the variant BB was found providing a useful proxy to trace the exclusively in the species Chloris introduction of this species. -The variant ciliata, C. dandyana, C. inflata, VV of the same phytolith category was Cynodon dactylon, C. nlemfuencis, only recorded in Paspalum fasciculatum.

Eleusine indica, Eragrostis japonica, E. maypurensis, E. pilosa, E. tenuifolia, -The silicified epidermal structure, Leptochloa virgata, and Piresia amorphous with projections, variant sympodica, making it a useful marker WW was only found in culms Guadua for Chloridoideae, although Piresia angustifolia, an ecologically and stands out from this group as the only culturally important Amazonian species.

bambusoid. In the same category, variant Variant XX of the same category AA was only present in the panicoid occurred at high density in the spikelets Gynerium sagittatum. Our variant DD of Oryza grandiglumis. This structure is of the same category is diagnostic for also caracterized by its relatively small the genus Pharus. This latter structure size (Fig. 2F).

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-Mammiform cells of variant AAA cell variant II was also common (Fig. 2).

were found in the panicoid species We observed this phytolith morphotype Coleataenia caricoides and the in 19 Amazonian species from varied bambusoid Arthrostylidium sp.

habitats (Table 2), distributed across five

subfamilies (Table 1). If we compare

Archaeological and paleoecological the contemporary grass flora of the area samples. In the 1000 year old with these 19 taxa (Giraldo-Cañas, D, archaeological sample from La Sardina, unpubl. data), five genera are shared the most conspicuous grass phytolith was between the two datasets: Guadua, amorphous with projections, diagnostic Gynerium sagittatum, Leptochloa, for the culms of Guadua angustifolia Paspalum, and Panicum. If other (Table 1). In Fig. 2 we present both elements of the contemporary flora are the archaeological and contemporary also found in fossil pollen, seeds, etc., phytoliths of this morphotype in G. that would suggest that the vegetation angustifolia. In the same region today in this region has remained fairly stable this species is a dominant component since the Miocene and would increase of the vegetation, suggesting that there confidence in the determination of the have not been significant changes over phytoliths. We should also note that the last 1000 years. The association of variant II of the category bulliform cells this species in a human cultural context is actually more complex that what we also suggests that the species may have have represented in Fig. 1 and requires been used by the local population.

further study. As many as 10 subvariants

may be recognized, likely providing an

In the paleoecological sample from even finer level of taxonomic resolution.

Santa Sofía grass phytoliths were Scanning electron microscopy will be well represented, including GSSCPs particularly useful to capture this level of widespread taxonomic distribution of detail (Fig. 3).

(trapeziform variant U), but the bulliform

28

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Figure 2.

Phytoliths of Amazonian grasses from D, amorphous with fine projections paleoecological (A) and archaeological (variant XX), characteristic structures (B) contexts and modern reference of the spikelets of Oryza grandiglumis collections (C-F). A, bulliform cell (ICN MHN FIT 1062). E, bilobate short (variant II) from the Miocene 15-12 cell with short acute projections and My (Colombia. Amazonas: Leticia, concave ends (variant I) from Oryza Santa Sofía 3-91). B, amorphous latifolia leaf (ICN MHN FIT 1067).

silicified structures (variant WW) F, trapeziform with sinuate base with with marginal proyections from two acute projections (variant Y), from Guadua angustifolia, associated with spikelets of Oryza grandiglumis (ICN

Terra Preta archaeological site from MHN FIT1062). Codes in parenthesis 1000 BP (Colombia. Amazonas: La refer to the accession numbers of the Sardina, Middle Caquetá River). C, slide preparations in the Phytolith amorphous with fine projections from Collection of the Instituto de Ciencias Guadua angustifolia (variant WW), Naturales (ICN, 2019).

characteristic structures of the culm.

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Figure 3. Phytoliths of Amazonian grasses (SEM). A and G, bilobate short cell. B, E and F, bilobate long cells. C and D, bulliform cells.

Cluster analyses and patterns at by only two species of Pharus in our subfamily level. In both separate and sample. Tribal or subtribal relations combined UPGMA analyses, we failed are not reflected in the clusters either.

to recover clusters that contained only Although 2/3 of the species in our dataset members of a single subfamily, with the are Panicoideae, we expected to recover exception of Pharoideae, represented distinct Bambusoideae, Chloridoideae,

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Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Oryzoideae and Aristidoideae clusters long cell phytoliths with a very thin in either the combined (Fig. 4) or central shaft, all of the varieties of this GSSCP only dataset (Fig. 5), but all four morphotype category that we observed subfamilies were interspersed with the in Aristidoideae were also found in panicoids throughout both dendrograms. panicoid grasses in our sample, and thus The GSSCP-only analysis was the they did not form a subfamily cluster.

one that gave results that most closely We explored the data further to see if the matched our hypothesis. In this dataset, general Aristid morphotype (Neumann et Chloridoideae were concentrated in two al. , 2017) is associated with a particular clusters, although the largest of these habitat or photosynthetic pathway in the was intermixed with two oryzoids and Amazonian panicoids (Table 2), but we a panicoid, and numerous chloridoid found no relation. The bambusoids, also species also fell outside of the two did not form a subfamily cluster because main clusters (Fig. 5), while within the distribution of the diagnostic variants these clusters, genera did not group (above) is at species or genus level.

together, but were dispersed throughout The same can be said for Oryzoideae.

the topology. In the same analysis, the The UPGMA analysis of only the two Pharidoideae did group together, silicified epidermal structures (Fig.

although in the combined analysis, 6) was the least resolved, with many the panicoid Digitaria fuscescens also collapsed branches and the clusters not formed part of this cluster. Although corresponding to subfamilies or lower the aristidoids in the Amazonian grass taxonomic levels, with the exception of flora have characteristic bilobate a few pairs of congeneric species.

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Figure 4. UPGMA analysis of combined matrix including all 54 phytolith variants: GSSCPs and silicified epidermal structures.<

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Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Figure 5. UPGMA analysis of matrix with 32 GSSCP variants.

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Figure 6. UPGMA analysis of matrix with 22 variants of (non GSSCP) silicified epidermal structures.

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Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Discussion

useful for diagnosing grass subfamilies,

have potential as diagnostic markers at

Potential of non-GSSCP phytoliths. species level.

Phytolith research in grasses (reviewed

in Piperno, 2006; Strömberg, 2018) has We must nevertheless acknowledge focused heavily on GSSCPs, but in our some limitations of this study. Because experience, silicified epidermal cells, we do not know a lot about what drives stomata, prickles, and trichomes often silification of epidermal cells and hairs appear in Amazonian archaeological we cannot interpret their biological contexts and here we have presented significance and we cannot be sure examples of silicified epidermal cells that presence of these structures in the recovered from archaeological and taxa reported here will be consistent paleoecological sediments that can be in all individuals of the same species, used to diagnose grasses to species level although the archaeological Guadua or at least greatly reduce the universe angustifolia example is encouraging.

of possible taxa. Based on the fact Strömberg (2016, 2018) suggests there that unique variants of epidermal cells may be some correlation with abundance were identified in several species in this of bulliform cells in sediments and study, we believe it is a promising area high-light environments, but this for future research, and given that some hypothesis requires further testing, and of these structures were found in culms it may be that for the Amazon region, and inflorescences, we concur with this generality will not hold (see Tables Piperno (2006) that it is worth expanding 1 and 2; Fig. 2). For future studies it phytolith reference collections to would be desireable to sample multiple include these organs. Bulliform cells populations of widespread species that are found only in grasses [although live in both open and forested habitats Albert Cristóbal (1995) erroneously to see how/if phytolith morphology and stated that they also occur in other abundance change with environmental commelinid monocots], and they are conditions.

highly variable in Amazonian species.

Because of their function in responding In Table 1 we included the category to hydric stress, phytoliths derived from “miscellaneous epidermal structures”

bulliform cells might be predicted to be which includes stomata and various more prevalent in C grasses, but this types of hairs. We did not subdivide this 4

is not the case; they are present in all category very finely, but future studies lineages, in forest understory species in this area could lead to finer taxonomic as well as grasses of open areas (Table resolution, given that hairs are often 2). We have detected additional variants important in diagnosing grass species.

in this phytolith category that remain As a final comment on anatomical data, to be described and their distribution we note that orientation of GSSCPs in the documented. Overall, we conclude that leaf tissues was emphasized by Rudall silicified epidermal structures while not et al. (2014) as being of taxonomic

Cinchonia Vol. 20, #1, 2025

35

importance, but orientation cannot be importance in the lowland Neotropics: determined from phytoliths found free it is the only subfamily with both C and 3

in sediments. Reference collections C photosynthesis and it also happens 4

for archaeological and paleoecological to be the most diverse subfamily in the studies are made from phytoliths Amazon. In our study we observed no extracted from calcinated leaf tissue, clear pattern of morphotype distribution not from histological preparations and within the subfamily, with unique so contemporary phytolith collections variants being restricted to one or few lack this information, but our method species (Table 1), a finding similar to that does have the advantage of isolating of Neumann et al. (2017) who surveyed silicified epidermal structures, which are a representative sample of West less likely to be detected in histological African grasses which also have a high preparations, as well as the advantage proportion of panicoids, nevertheless noted by Piperno (2006) of being able they found less overlap of morphotypes to see GSSCPs from multiple angles.

among subfamilies, compared with our

much larger Amazonian sample. The

Taxonomic distribution of GSSCPs. same authors also stressed that in West While it is true that certain morphotypes Africa, there is no clear relationship have been identified as providing between GSCCP morphotypes and taxonomic resolution at the subfamily specific ecological conditions, a result level, for example in chloridoid and echoed in our findings here.

pooid grasses (Brown, 1984; Piperno

& Pearsall, 1998; Strömberg, 2016), it Even when phytolith morphologies do cannot be generalized that phytoliths not overlap between subfamilies, there are only or even most useful at this is still need for caution in applying taxonomic level. Much in the way that patterns too broadly. For example, chloroplast genes like rbc L and mat K Bambusoideae includes morphotypes were once used only in systematic found only in this subfamily, but there is studies at family level and above, we no single variant that is distributed in all now know that autapomorphies in these bambusoids. Piperno & Pearsall (1998) genes can be useful diagnostic markers included a large number of species of the at species level. The same can be said tribe Olyreae in their neotropical grass for phytoliths. Broadening the sample study, finding diagnostic phytoliths both geographically and taxonomically at subtribe and generic levels in this is necessary to affirm or refute group, but lowland tropical species have established patterns. As more studies other diagnostic morphologies ( Piresia, are published, we expect to see more Pariana, some Guadua species). We overlap of broad phytolith categories stress the importance of sampling, in multiple subfamilies, while variation both at regional and taxonomic levels at a finer scale becomes increasingly to better elucidate patterns of phytolith important (Piperno, 2006; Neumann et distribution within and among grass al. , 2017). Panicoideae is of particular subfamilies.

36

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Final considerations. We have high as in other studies: Neumann et confirmed

unusual

phytolith al. (2017) recognized 153 variants in morphologies in some previously 54 species from 32 genera of African sampled taxa like Pharus and grasses, while Zucol (1998, 2000) found Streptochaeta, so even though we did close to 50 variants each in samples not sample multiple individuals from of only eight species of Panicum and different populations, congruence across Paspalum. Subjectivity remains an these independent studies suggests that outstanding issue, and we look forward morphologies are consistent within to new developments in the use of pattern individual species. We have also found recognition software (T. Gallaher, pers.

additional structures not previously comm.) to compare how the specialist reported. It is therefore possible that eye performs against machine learning in future studies, other authors who algorithms. Finally, we would like to sample the same taxa reported here may highlight that well-curated herbarium find additional structures as well. We collections are an important source have not done counts to show relative of material for phytolith reference abundance of different morphotypes collections. We also underscore the within a given species and this is a importance of collaboration with worthwhile goal of future research, as is taxonomic specialists to ensure that the SEM study of the morphotypes.

material is properly determined and to

aid in the interpretation of patterns of In this study we recognized 54 phytolith variation within large families.

morphotype variants, which is not as

Cinchonia Vol. 20, #1, 2025

37

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40

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Zhao, Z. J., D. M. Pearsall, R. A. Benfer & Acknowledgements D. R. Piperno. 1998. Distinguishing rice

( Oriza sativa Poaceae) from wild Oryza We thank Carina Hoorn (Institute for species throung phytolith analysis. II: Biodiversity and Ecosystem Dynamics, Finalized method. Economic Botany 52: University of Amsterdam, The 134-145.

Netherlands) for sharing her Miocene

sediment samples with us, Cristian

Zucol, A. 1992. Microfitolitos: Pinzón ( Instituto de Ecología, Xalapa, I. Antecedentes y terminología. Mexico) for assistance with the cluster Ameghiniana 29: 353-362.

analyses, and Universidad Nacional

de Colombia. We thank the reviewers Zucol, A. 1998. Microfitolitos de las (Prof. Dr. Orlando Rangel and Prof. Dr.

Poaceae argentinas: II. Microfitolitos Alexis Jaramillo-Justinico) and editors foliares de algunas especies del género for their valuable comments on the Panicum (Poaceae, Paniceae) de la manuscript.

provincia de Entre Ríos. Darwiniana

36: 29-50.

Conflicts of interest. The authors

Zucol, A. 2000. Fitolitos de Poaceae declare none conflicts of interest in the de Argentina. III. Fitolitos foliares publication.

de especies del género Paspalum

(Paniceae) en la provincia de Entre

Ríos. Darwiniana 38: 11-32.

Cinchonia Vol. 20, #1, 2025

41

- -

Mammi

cal Cell

form-Coni

AAA

-

-

-ZZ

Misc. Epi

ZZ

YY

YY

YY

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YY

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tions

WW

-ZZ).

Projec

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-

-

Elon gate Epi

RR

PP

PP

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PP

dermal Cell

OO- QQ

OO-RR

-

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II

Bulli form Cell

FF

HH-II

HH

HH

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JJ-KK

HH

-

Car inate

EE

- -

-Rect

Suborbic ular angular

Amazonian grasses (*see Fig. 1

Cross

a- -

Tr

S

pezi form

S-T

U

U

U

U

R-U

U

U

U

W

U

- -

O

P

Poly lo bate

-

N

L

L

J

Bilo bate Long Cell

M

-

D

A

A

A

A

A

Bilo bate Short Cell

A-G

Londoño

Schrad. ex

Pilg.

Lam.

Kunth

Trin.

Munro

Munro

Trin.

Huber

(Nees) Kunth

sp.

ospiculata

. Distribution of phytolith morphotypes in species of

.

ostylidium

eptochaeta spicata

## Table 1

### Taxon

## Anomochlooideae

### Str Nees

## Aristidoideae

### Aristida capillacea

Aristida longifolia

Aristida riparia

Aristida torta

## Bambusoideae

### Arthr

Cryptochloa unispiculata Soderstr

Guadua angustifolia

Guadua glomerata

Guadua macr & L.G. Clark

Guadua superba

Guadua venezuelae

Guadua weberbaueri

42

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas

- -

Mammi

cal Cell

form-Coni

-

-

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ZZ

ZZ

ZZ

ZZ

ZZ

dermal Struc tures*

-

-

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-

-

Elon gate Epi

PP

PP

PP

PP

PP

dermal Cell

-

Bulli form Cell

GG

HH

GG- HH-II

HH

II-JJ

HH-II

HH-II

-

Car inate

- -

-Rect

BB

BB

BB

BB

BB

BB

Suborbic ular angular

BB-CC

Z

Cross

a- -

V

W

Tr

T

T

T

pezi form

T-

V-

U

U

U

U

- -

P

P

Poly lo bate

O-P

-

K

Bilo bate Long Cell

-

B

A

C

B

G

Bilo bate Short Cell

B-C-G

A-B

B-H

.

. M.

Adams

.

. M.

Vanderyst

Aubl.

Sagot ex Döll

(Steud.)

(Döll) Swallen

.

(J. Presl) P

C.D.

(L.) Pers.

L.

(Retz.) P

Swallen

Sw.

Sw.

(L.) Sw

(Nees) P

(L.) Gaertn.

esia goeldii

esia sympodica

Taxon

Olyra latifololia

Pariana campestris

Pariana radiciflora

Pir

Pir

Raddiella esenbeckii Calderón & Soderstr Chloridoideae

Chloris barbata

Chloris ciliata

Chloris dandyana

Chloris radiata

Cynodon dactylon

Cynodon nlemfuensis

Dinebra panicea Peterson & N. Snow Dinebra panicoides M. Peterson & N. Snow Dinebra scabra Peterson & N. Snow Eleusine indica

Cinchonia Vol. 20, #1, 2025

43

- -

Mammi

cal Cell

form-Coni

-

-

Misc. Epi

ZZ

ZZ

ZZ

YY

ZZ

YY

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-

-

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-

-

Elon gate Epi

PP

PP

PP

SS

dermal Cell

-

Bulli form Cell

HH-II

-

Car inate

- -

-Rect

CC

BB

BB

AA

BB

CC

BB

BB

CC

BB

Suborbic ular angular

BB-CC

Cross

a- -

Tr pezi form

W

W

U

U

U

U

U

U

U

- -

Poly lo bate

-

J

L

Bilo bate Long Cell

-

B

C

A

B

B

Bilo bate Short Cell

A-B

A-D

.

.

.

.

(Kunth)

. Beauv

. Beauv

. Beauv

(Kunth)

(Desf.)

Schrad. ex

(Roxb.)

(Lam.)

(Michx.)

(Thunb.)

(A. Rich.)

(L.) P

ens

(L.) R. Br

ensis

(L.) P

(L.) P

ovir

gata

ostis acutiflora

ostis atr

ostis bahiensis

ostis ciliaris

ostis gangetica

ostis hypnoides

ostis japonica

ostis maypur

ostis pectinacea

ostis pilosa

ostis tenella

ostis tenuifolia

Taxon

Eragr Nees

Eragr Trin. ex Steud.

Eragr Schult.

Eragr

Eragr Steud.

Eragr Britton, Stern & Poggenb.

Eragr Trin.

Eragr Steud.

Eragr Nees

Eragr

Eragr ex Roem. & Schult.

Eragr Hochst. ex Steud.

Leptochloa vir

44

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas

- -

Mammi

cal Cell

form-Coni

-

-

-ZZ

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YY

YY

ZZ

YY

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YY

-

-

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XX

Projec tions

-

-

Elon gate Epi

PP

TT

NN

NN

dermal Cell

PP-RR-

-

II

II

II

Bulli form Cell

HH- II-LL

HH

-

Car inate

- -

-Rect

CC

CC

CC

CC

CC

Suborbic ular angular

Cross

a- -

Tr pezi form

W

W

U-Y

U-W

U

U

W

U-W

W

W

- -

P

P

Poly lo bate

-

K

J

K

Bilo bate Long Cell

-

B

I

B

B

A

A

B

D

Bilo bate Short Cell

A-B

.

Kunth

Kunth

.

.) P

(Mart. ex

.-Cañas

C.E.

(Flüggé)

Hitchc.

(Sw

(Döll) Prod.

Gir

.

(Kunth)

(Raddi)

P. Beauv

Desv

engii

essus

L.

eus

obolus cubensis

obolus jacquemontii

obolus tenuissimus

opogon leucostachyus

opogon sor

.

eptogyna americana

Taxon

Spor

Spor

Spor Schrank) Kuntze

## Oryzoideae

### Oryza grandiglumis

Oryza latifolia

Oryza sativa

Str Hubb. Panicoideae

Andr

Anthaenantia lanata Benth.

Arthr

Axonopus aur

Axonopus compr Beauv

Axonopus fissifolius Kuhlm.

Axonopus leptostachyus Hitchc.

Cinchonia Vol. 20, #1, 2025

45

- -

Mammi

cal Cell

form-Coni

AAA

-

-

Misc. Epi

ZZ

ZZ

ZZ

ZZ

YY

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-

-

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-

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QQ

PP

RR

PP

SS

PP

PP

dermal Cell

PP-SS

-

Bulli form Cell

HH-II

-

Car inate

- -

-Rect

Suborbic ular angular

Cross

a- -

Tr

S

S

pezi form

U

U

W

U

U-W

W

W

- -

P

P

P

P

P

P

P

Poly lo bate

O-P

-

L

K

Bilo bate Long Cell

M

J-K-M

J-M

-

B

D

B

B

B

A

Bilo bate Short Cell

A-D

B-G-H

B-D

B-C

A-D

A-D

.-Cañas

A. Black

(L).

.) J. R.

illd.

(Nees ex

(DC.) Stapf

W

Gir

(J. Presl)

(Mez) Chase

G.

(Flüggé)

(Sw

(L.) Link

L.

(Lam.) Roem.

(L.) Fedde

onei

(Retz.) Koeler

Taxon

Axonopus morr

Axonopus purpusii

Axonopus schultesii

Axonopus scoparius Kuhlm.

Cenchrus polystachios Morrone

Coix lacryma-jobi

Coleataenia carioides Trin.) Soreng Cymbopogon citratus

Dallwatsonia pilosa Grande

Dallwatsonia polygonata (Schrad.) J. R. Grande Digitaria bicornis & Schult.

Digitaria ciliaris

Digitaria fuscescens Henrard

Digitaria horizontalis

Digitaria insularis

Echinochloa colona

46

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas

- -

Mammi

cal Cell

form-Coni

-

-

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Misc. Epi

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YY

ZZ

YY

ZZ

ZZ

dermal Struc tures*

YY

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-

-

Amor phous with Projec tions

-

-

Elon gate Epi

TT

PP

SS

PP

dermal Cell

OO-PP

-

Bulli form Cell

HH

HH-II

HH-II

HH-II

KK

-

Car inate

- -

-Rect

AA

Suborbic ular angular

Cross

a- -

Tr

R

pezi form

U

W

U

U

U

S-U

W

U

- -

P

P

P

P

P

Poly lo bate

-

K

K

Bilo bate Long Cell

-

A

D

B

B

A

A

Bilo bate Short Cell

B-G-H

B-G-H

A-B

B-D

.

. ex

.

(Kunth)

.) Chase

.)

(Raddi)

Döll

(Nees ex

.) Munro

P. Beauv

(Poir

(Aubl.) P

(L.) Desv

(Kunth)

(Sw .

obs

(Sw

(J. Presl & C.

ensis

eviscr

.

Taxon

Echinochloa polystachya Hitchc.

Echinolaena inflexa

Eriochloa punctata Ham.

Gynerium sagittatum Beauv

Homolepis atur Chase

Homolepis glutinosa Zuloaga & Soderstr Hymenachne amplexicaulis (Rudge) Nees Hymenachne donacifolia Chase

Ichnanthus br

Ichnanthus calvescens Trin.) Döll

Ichnanthus pallens ex Benth.

Ichnanthus panicoides

Ichnanthus tenuis Presl) Hitchc. & Chase

Cinchonia Vol. 20, #1, 2025

47

- -

Mammi

cal Cell

form-Coni

-

-

Misc. Epi

ZZ

ZZ

ZZ

ZZ

YY

ZZ

ZZ

ZZ

dermal Struc tures*

-

-

Amor phous with Projec tions

-

-

Elon gate Epi

PP

PP

PP

PP

PP

PP

RR

dermal Cell

-

Bulli form Cell

HH- KK

MM

-

Car inate

EE

- -

-Rect

Suborbic ular angular

Cross

a- -

Tr pezi form

W

U

U

S-W

U

U

- -

P

P

P

P

Poly lo bate

O-P

-

J

L

K

Bilo bate Long Cell

-

A

A

B

B

B

D

Bilo bate Short Cell

B-D

A-B

A-B

B-D

A-C

G-H

A-B-E

.

.)

. ex

(Nees ex

(Jacq.)

(Raddi)

(Poir

(Hack.)

(Hochst. ex

(Kunth)

(Desv

P. Beauv

Hitchc. & Chase

Hitchc.

.L. Jacobs

(Griseb.) Hitchc.

illd.) Zizka(W

sp.

ocerrima

ghoidea

epens

Taxon

Ichnanthus

Lasiacis ligulata

Lasiacis pr Hitchc.

Lasiacis ruscifolia Hitchc.

Lasiacis scabrior

Lasiacis sloanei

Lasiacis sor Ham.) Hitchc. & Chase Louisiella elephantipes Trin.) Zuloaga Megathyrsus maximus B.K Simon & S.W

Melinis minutiflora

Melinis r

Mesosetum loliiforme Steud.) Chase

Ocellochloa pulchella Zuloaga & Morrone Ocellochloa stolonifera Zuloaga & Morrone

48

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas

- -

Mammi

cal Cell

form-Coni

-

-

Misc. Epi

ZZ

ZZ

ZZ

YY

dermal Struc tures*

-

-

Amor phous with Projec tions

-

-

Elon gate Epi

RR

PP

PP

PP

RR

PP

PP

SS

VV

dermal Cell

PP-RR

PP-SS-

-

JJ

Bulli form Cell

HH

HH

HH

-

Car inate

EE

- -

-Rect

Suborbic ular angular

Cross

a- -

Tr pezi form

W

S-W

U

W

U

U-W

U

U

U

U-W

- -

P

P

P

P

P

P

P

P

P

Poly lo bate

-

K

Bilo bate Long Cell

-

B

D

A

B

D

Bilo bate Short Cell

A-G-H

A-B

A-B

A-D

B-G-H

A-B

A-B

A-B

B-D

A-D

.

.

.

. Beauv

Michx

Steud.

illd. ex

(Retz.) P

(Döll)

P.J.

W

(L.) P

Lam

Nees

Humb. &

Sw.

Kunth

Sw.

(Rich.) P

Lam

Roem. & Schult.

oides

.

.

gius

Taxon

Oplismenus burmannii Beauv

Oplismenus hirtellus Beauv

Orthoclada laxa

Otachyrium versicolor Henrard

Panicum cayennense

Panicum dichotomiflorum

Panicum hirtum

Panicum olyr

Panicum rudgei

Panicum trichanthum

Panicum trichoides

Panicum tricholaenoides

Paspalum carinatum Bonpl. ex Flüggé Paspalum conjugatum Ber

Paspalum decumbens

Paspalum fasciculatum Flüggé

Cinchonia Vol. 20, #1, 2025

49

- -

Mammi

cal Cell

form-Coni

-

-

-ZZ

Misc. Epi

ZZ

ZZ

ZZ

dermal Struc tures*

YY

-

-

Amor phous with Projec tions

-

-

Elon gate Epi

SS

PP

QQ

PP

PP

dermal Cell

RR-SS

-

Bulli form Cell

HH- II- MM

-

Car inate

- -

-Rect

CC

Suborbic ular angular

Cross

a- -

Tr

S

pezi form

U-W

U

U-W

U

W

S-U

U-W

U

U

- -

P

P

P

P

P

P

P

Q

Poly lo bate

-

K

L

Bilo bate Long Cell

-

B

D

C

A

B

A

D

B

A

D

Bilo bate Short Cell

B-G-H

B-E

C-D

A-D

.

Trin.

Desv

.

(Nees

(Lam.)

Steud.

Munro ex

gius

Trin.

Poir

S. Denham

Kunth

Nees ex

Flüggé

(Mez) S.

L.

Lam.

E. Fourn.

P.J. Ber

gatum

epens

.

Trin.) Zuloaga & Morrone

Taxon

Paspalum foliiforme

Paspalum geminiflorum

Paspalum hyalinum

Paspalum intermedium Morong & Britton Paspalum lanciflorum

Paspalum laxum

Paspalum melanospermum ex Poir

Paspalum minus

Paspalum notatum

Paspalum orbiculatum

Paspalum pulchellum

Paspalum r

Paspalum trinitense Denham

Paspalum vir

Trichanthecium cyanescens ex

Trichanthecium nervosum

50

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas

- -

Mammi

cal Cell

form-Coni

-

-

Misc. Epi

YY

YY

dermal Struc tures*

-

-

Amor phous with Projec tions

-

-

Elon gate Epi

UU

PP

PP

dermal Cell

PP-RR-

-

Bulli form Cell

-

Car inate

EE

EE

- -

-Rect

Suborbic ular angular

Cross

a- -

Tr pezi form

W

X

U

W

U

U-W

W

W

- -

P

P

P

Poly lo bate

-

L

K

Bilo bate Long Cell

L-M

-

G

B

D

D

A

B

Bilo bate Short Cell

B-D

A-F

D-G

B-C

A-B-D

A-B-D

C-D

L.

.)

(Roth)

(Flüggé)

(Griseb.)

.) Zuloaga

(Poir

(Lam) Roem. &

(L.) Moench.

(Sw

Raddi

Zuloaga & Morrone

ochloa acuta

rin.)

guélen

ghastrum setosum

ghum bicolor

Taxon

Trichanthecium orinocanum (Luces) Zuloaga & Morrone Trichanthecium parvifolium (Lam.) Zuloaga & Morrone Trichanthecium polycomum (T

Trichanthecium pyrularium (Hitchc. & Chase) Zuloaga & Morrone Reimar Hitchc.

Saccharum officinarum

Setaria parviflora Ker

Setaria sulcata

Setaria vulpiseta Schult.

Sor Hitchc.

Sor

Steinchisma laxa

Stephostachys mertensii Zuloaga & Morrone

Cinchonia Vol. 20, #1, 2025

51

- -

Mammi

cal Cell

form-Coni

-

-

-ZZ

Misc. Epi

YY

ZZ

dermal Struc tures*

YY

-

-

Amor phous with Projec tions

-

-

Elon gate Epi

VV

TT

dermal Cell

RR-SS

-

II

Bulli form Cell

II-KK

KK

-

Car inate

- -

-Rect

CC

DD

DD

Suborbic ular angular

AA-BB-

Cross

a- -

Tr pezi form

S-U

- -

P

Poly lo bate

P-Q

-

J

Bilo bate Long Cell

-

A

A

Bilo bate Short Cell

B-C

A-B-D

A-B-C

A-C- D-F- G-H

T.Q.

Andersson

H.C. Cutler

(Forssk.)

L.

Döll

L.

escens

Anderson

## oideae

### ochloa mutica

Taxon

Trachypogon vestitus

Tripsacum australe & E.S.

Ur Nguyen

Zea mays

## Phar

### Pharus latifolius

Pharus vir

52

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Table 2. Habitat and photosynthetic pathways of Amazonian grasses, adapted from Giraldo-Cañas (2013) and Morcote-Ríos et al. (2015). Subfamily species distribution as Table 1.

Photosynthetic

Taxon

Habitat

Pathway

Streptochaeta spicata Schrad. ex Nees Understory of mature humid low-C3

land forests

Aristida capillacea Lam.

Savanas, slopes, rock out crops,

C4

grasslands

Aristida longifolia Trin.

Savannas

C3

Aristida riparia Trin.

Savannas

C4

Aristida torta (Nees) Kunth

Savannas

C4

Arthrostylidium sp.

Forest edges

C3

Cryptochloa unispiculata Soderstr.

Forest understory and forest edge

C3

Guadua angustifolia Kunth

Secondary forest, riparian envi-

C3

ronments

Guadua glomerata Munro

Secondary forest, riparian envi-

C3

ronments

Guadua macrospiculata Londono &

Secondary forest, riparian envi-

C3

L.G. Clark

ronments

Guadua superba Huber

Secondary forest, riparian envi-

C3

ronments

Guadua venezuelae Munro

Forest and riparian environments

C3

Guadua weberbaueri Pilg.

Forest and riparian environments

C3

Olyra latifololia L.

Forest edges

C3

Pariana campestris Aubl.

Understory and forest edges

C3

Pariana radiciflora Sagot ex Döll

Understory and forest edges

C3

Piresia goeldii Swallen

Humid forest understory

C3

Piresia sympodica (Döll) Swallen

Understory and forest edges

C3

Raddiella esenbeckii (Steud.) Calderón Open areas with rocky or sandy C3

& Soderstr.

substrates

Chloris barbata Sw.

Disturbed open areas

C4

Chloris ciliata Sw.

Disturbed open areas

C4

Chloris dandyana C.D. Adams

Disturbed open areas

C4

Chloris radiata (L.) Sw.

Disturbed open areas

C4

Cynodon dactylon (L.) Pers.

Disturbed open areas

C4

Cynodon nlemfuensis Vanderyst

Disturbed open areas, roadsides

C4

Dinebra panicea (Retz.) P. M.

Disturbed open areas

C4

Peterson & N. Snow

Cinchonia Vol. 20, #1, 2025

53

Photosynthetic

Taxon

Habitat

Pathway

Dinebra panicoides (J. Presl) P. M.

Disturbed open areas

C4

Peterson & N. Snow

Dinebra scabra (Nees) P. M. Peterson Disturbed open areas C4

& N. Snow

Eleusine indica (L.) Gaertn.

Disturbed open areas, crops fields,

C4

roadsides

Eragrostis acutiflora (Kunth) Nees

Savannas, “herbazales” (areas

C4

dominated by herbaceous, non

gramonoid vegetation), roadsides,

disturbed open areas

Eragrostis atrovirens (Desf.) Trin. ex Disturbed open areas

C4

Steud.

Eragrostis bahiensis Schrad. ex Schult. Disturbed open areas C4

Eragrostis ciliaris (L.) R. Br.

Open field, disturbed open areas,

C4

roadsides, abandoned clearings

Eragrostis gangetica (Roxb.) Steud.

Disturbed open areas

C4

Eragrostis hypnoides (Lam.) Britton,

Open areas, wet, sandy substrates,

C4

Stern & Poggenb.

river and stream banks, lakeshores

Eragrostis japonica (Thunb.) Trin.

Disturbed open areas, open fields

C4

Eragrostis maypurensis (Kunth) Steud. Savannas, “herbazales” (ar-C4

eas dominated by herbaceous,

non-graminoid vegetation) dis-

turbed open areas, roadsides

Eragrostis pectinacea (Michx.) Nees

Savannas , “herbazales” (ar-

C4

eas dominated by herbaceous,

non-graminoid vegetation), dis-

turbed open, roadsides

Eragrostis pilosa (L.) P. Beauv.

Disturbed open areas, abandoned

C4

clearings with low-statured veg-

etation

Eragrostis tenella (L.) P. Beauv. ex

Disturbed open areas, roadsides,

C4

Roem. & Schult.

abandoned clearings

Eragrostis tenuifolia (A. Rich.)

Disturbed open areas, roadsides,

C4

Hochst. ex Steud.

abandoned clearings with low-stat-

ured vegetation, open fields

Leptochloa virgata (L.) P. Beauv.

Disturbed open areas

C4

Sporobolus cubensis Hitchc.

Savannas

C4

Sporobolus jacquemontii Kunth

Disturbed open areas, savannas,

C4

roadsides

Sporobolus tenuissimus (Mart. ex

Disturbed open areas, roadsides

C4

Schrank) Kuntze

54

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Photosynthetic

Taxon

Habitat

Pathway

Oryza grandiglumis (Döll) Prod.

Marshy environments, swamps,

C3

wet fields, ditches and banks of

ponds and small streams

Oryza latifolia Desv.

Marshy environments, swamps,

C3

wet fields, ditches and banks of

ponds and small streams

Oryza sativa L.

Lowland and mid elevations in

C3

open vegetation on very wet or

saturated soils

Streptogyna americana C.E. Hubb.

Humid forest understory

C3

Andropogon leucostachyus Kunth

Savannas, disturbed open areas

C4

Anthaenantia lanata (Kunth) Benth.

Savannas, “herbazales” (ar-

C4

eas dominated by herbaceous,

non-graminoid vegetation), rock

outcrops, disturbed open areas

Arthropogon sorengii Gir.-Cañas

Savannas and “herbazales” (ar-

C4

eas dominated by herbaceous,

non-graminoid vegetation) associ-

ated with rock outcrops

Axonopus aureus P. Beauv.

Savannas, disturbed open areas

C4

Axonopus compressus (Sw.) P. Beauv.

Savannas, disturbed open areas

C4

Axonopus fissifolius (Raddi) Kuhlm.

Savannas, disturbed open areas

C4

Axonopus leptostachyus (Flüggé)

Savannas, “herbazales” (areas

C4

Hitchc.

dominated by herbaceous, non-

graminoid vegetation), rock out-

crops

Axonopus morronei Gir.-Cañas

Savannas

C4

Axonopus purpusii (Mez) Chase

Savannas, disturbed open areas

C4

Axonopus schultesii G. A. Black

Savanna, “herbazales” (ar-

C4

eas dominated by herbaceous,

non-graminoid vegetation), rock

outcrops

Axonopus scoparius (Flüggé) Kuhlm.

Disturbed open areas, open fields

C4

Cenchrus polystachios (L). Morrone

Disturbed open areas, open areas

C4

Coix lacryma-jobi L.

Crops, open riparian areas

C4

Coleataenia carioides (Nees ex Trin.) Savannas, “herbazales” (areas C4

Soreng

dominated by herbaceous, non-

gramonoid vegetation), rock

outcrops

Cymbopogon citratus (DC.) Stapf

Cultivated in open areas

C4

Cinchonia Vol. 20, #1, 2025

55

Photosynthetic

Taxon

Habitat

Pathway

Dallwatsonia pilosa (Sw.) J. R. Grande Savannas, disturbed open areas, C3

roadsides, pastures, forest clear-

ings

Dallwatsonia polygonata (Schrad.) J.

Disturbed open areas, roadsides,

C3

R. Grande

banks of rivers and streams

Digitaria bicornis (Lam.) Roem. & Savannas, disturbed open areas

C4

Schult.

Digitaria ciliaris (Retz.) Koeler

Savannas, disturbed open areas

C4

Digitaria fuscescens (J. Presl) Henrard Disturbed open areas C4

Digitaria horizontalis Willd.

Disturbed open areas, savannas,

C4

rock outcrops

Digitaria insularis (L.) Fedde

Disturbed open areas

C4

Echinochloa colona (L.) Link

Disturbed open areas

C4

Echinochloa polystachya (Kunth)

Back of rivers, lakes and swamps

C4

Hitchc.

Echinolaena inflexa (Poir.) Chase

Savannas, open areas

C4

Eriochloa punctata (L.) Desv. ex Ham. Forest edges, riverbanks C4

Gynerium sagittatum (Aubl.) P. Beauv. Open rocky, stream and riverbanks C3

Homolepis aturensis (Kunth) Chase

Savannas, wet open areas, scrub-

C3

lands

Homolepis glutinosa (Sw.) Zuloaga & Forest edges and open areas C3

Soderstr.

Hymenachne amplexicaulis (Rudge)

Banks of rivers, lakes and swamps

C3

Nees

Hymenachne donacifolia (Raddi)

Banks of rivers, lakes and swamps

C3

Chase

Ichnanthus breviscrobs Döll

Edges and interior of humid for-

C3

ests

Ichnanthus calvescens (Nees ex Trin.) Edges and interior of humid for-C3

Döll

ests

Ichnanthus pallens(Sw.) Munro ex

Edges and interior of humid for-

C3

Benth.

ests

Ichnanthus panicoides P. Beauv.

Edges and interior of humid for-

C3

ests

Ichnanthus tenuis (J. Presl & C. Presl) Edges and interior of humid for-C3

Hitchc. & Chase

ests

Ichnanthus sp.

Edges and interior of humid for-

C3

ests

Lasiacis ligulata Hitchc. & Chase Edges of humid forest

C3

56

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Photosynthetic

Taxon

Habitat

Pathway

Lasiacis procerrima (Hack.) Hitchc.

Disturbed open areas, secondary

C3

vegetation, open fields, roadsides

Lasiacis ruscifolia (Kunth) Hitchc.

Edges and interior of humid for-

C3

ests, secundary vegetation

Lasiacis scabrior Hitchc.

Edges of humid forest, secondary

C3

vegetation

Lasiacis sloanei (Griseb.) Hitchc.

Edges of humid forest, secondary

C3

vegetation

Lasiacis sorghoidea (Desv. ex Ham.)

Edges of humid forest, secondary

C3

Hitchc. & Chase

vegetation

Louisiella elephantipes (Nees ex Trin.) Banks of rivers, lakes and swamps C4

Zuloaga

Megathyrsus maximus (Jacq.) B.K

Disturbed open areas, roadsides,

C4

Simon & S.W.L. Jacobs

pastures, abandoned clearings with

low-statured vegetation

Melinis minutiflora P. Beauv.

Disturbed open areas

C4

Melinis repens (Willd.) Zizka

Disturbed open areas

C4

Mesosetum loliiforme (Hochst. ex

Savannas and “herbazales” (ar-

C4

Steud.) Chase

eas dominated by herbaceous,

non-graminoid vegetation)

Ocellochloa pulchella (Raddi) Zuloaga Forest edges, coffee plantations, C3

& Morrone

roadsides

Ocellochloa stolonifera (Poir.)

Sandy, humid areas, forest edges,

C3

Zuloaga & Morrone

banks of rivers and streams

Oplismenus burmannii (Retz.) P.

Disturbed open areas and fields

C3

Beauv.

with light shade, open woods

Oplismenus hirtellus (L.) P. Beauv.

Disturbed open areas and fields

C3

with light shade, open woods

Orthoclada laxa (Rich.) P. Beauv.

Understory of humid forests, for-

C3

est edges, cacao plantations

Otachyrium versicolor (Döll) Henrard

Savannas, “herbazales” (ar-

C4

eas dominated by herbaceous,

non-graminoid vegetation), rock

outcrops

Panicum cayennense Lam.

Savannas, disturbed open areas

C4

Panicum dichotomiflorum Michx.

Banks of rivers, lakes and swamps

C4

Panicum hirtum Lam.

In forest clearings, forest edges,

C3

river banks

Panicum olyroides Kunth

Savannas, “herbazales” (ar-

C4

eas dominated by herbaceous,

non-graminoid vegetation), rock

outcrops

Cinchonia Vol. 20, #1, 2025

57

Photosynthetic

Taxon

Habitat

Pathway

Panicum rudgei Roem. & Schult.

Savannas, disturbed open areas

C4

Panicum trichanthum Nees

In wet open areas, banks of rivers,

C3

lakes and swamps

Panicum trichoides Sw.

In wet open areas, shady areas,

C3

understory of humid forest, forest

edges

Panicum tricholaenoides Steud.

Banks of rivers, lakes and swamps

C4

Paspalum carinatum Humb. & Bonpl. Savannas , “herbazales” (ar-C4

ex Flüggé

eas dominated by herbaceous,

non-graminoid vegetation), rock

outcrops

Paspalum conjugatum P.J. Bergius

Savannas, patures, disturbed open

C4

areas

Paspalum decumbens Sw.

Forest edges, roadsides

C4

Paspalum fasciculatum Willd. ex

Bank of river, pastures and humid

C4

Flüggé

savannas, disturbed open areas

Paspalum foliiforme S. Denham

Savannas and open areas

C4

Paspalum geminiflorum Steud.

Open areas

C4

Paspalum hyalinum Nees ex Trin.

Savannas, “herbazales” (areas

C4

dominated by herbaceous, non

graminoid vegetation), rock out-

crops

Paspalum intermedium Munro ex

Savannas, “herbazales” (areas

C4

Morong & Britton

dominated by herbaceous, non-

graminoid vegetation), rock out-

crops

Paspalum lanciflorum Trin.

Savannas, open areas

C4

Paspalum laxum Lam.

River Banks

C4

Paspalum melanospermum Desv. ex

Open areas

C4

Poir.

Paspalum minus E. Fourn.

Savannas, disturbed open areas

C4

Paspalum notatum Flüggé

Savannas, pastures, disturbed open

C4

areas

Paspalum orbiculatum Poir.

Savannas, disturbed open areas

C4

Paspalum pulchellum Kunth

Savannas, “herbazales” (ar-

C4

eas dominated by herbaceous,

non-graminoid vegetation), rock

outcrops

Paspalum repens P.J. Bergius

Banks of rivers, lakes and swamps

C4

Paspalum trinitense (Mez) S. Denham Savannas C4

Paspalum virgatum L.

Wet, disturbed open areas

C4

58

Morcote-Ríos et al.: Phytoliths, gramíneas amazónicas Photosynthetic

Taxon

Habitat

Pathway

Trichanthecium nervosum (Lam.)

Savannas, “herbazales” (ar-

C3

Zuloaga & Morrone

eas dominated by herbaceous,

non-graminoid vegetation)

Trichanthecium orinocanum (Luces)

Humid savannas

C3

Zuloaga & Morrone

Trichanthecium parvifolium (Lam.)

Savannas, banks of rivers and

C3

Zuloaga & Morrone

lakes

Trichanthecium polycomum (Trin.)

Savannas, “herbazales” (ar-

C3

Zuloaga & Morrone

eas dominated by herbaceous,

non-graminoid vegetations, rock

outcrops

Trichanthecium pyrularium (Hitchc. & In wet, open areas C3

Chase) Zuloaga & Morrone

Reimarochloa acuta (Flüggé) Hitchc.

Savannas

C4

Saccharum officinarum L.

Cultivated in open areas

C4

Setaria parviflora (Poir.) Kerguélen

Savannas, conserved or disturbed

C4

open areas

Setaria sulcata Raddi

Shady places, river banks, forest

C4

edges

Setaria vulpiseta (Lam) Roem. & Roadsides, forest edges

C4

Schult.

Sorghastrum setosum (Griseb.) Hitchc. Savannas and open areas C4

Sorghum bicolor (L.) Moench.

Disturbed open areas, open fields

C4

Steinchisma laxa (Sw.) Zuloaga

Savannas, disturbed open areas,

C3

pastures, roadsides

Stephostachys mertensii (Roth)

Bank of river, lakes and swamps

C3

Zuloaga & Morrone

Trachypogon vestitus Andersson

Savannas, “herbazales” (ar-

C4

eas dominated by herbaceous,

non-graminoid vegetation), rock

outcrops

Tripsacum australe H.C. Cutler & E.S. Savannas and open areas C4

Anderson

Urochloa mutica (Forssk.) T.Q.

Savannas, pastures, disturbed open

C4

Nguyen

areas

Zea mays L.

Cultivated in open areas

C4

Pharus latifolius L.

Humid forest understory

C3

Pharus virescens Döll

Humid forest understory

C3