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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Echinolaena Desv.

Excluding Chasechloa

Habit, vegetative morphology. Annual, or perennial; rhizomatous to stoloniferous. Culms herbaceous; branched above. The branching simple. Culm nodes hairy, or glabrous. Culm internodes solid. Leaves not basally aggregated; non-auriculate. Leaf blades linear to lanceolate; broad, or narrow; cordate; tending to pseudopetiolate, or not pseudopetiolate; without cross venation.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant, or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile (the sessile members often aborted).

Inflorescence. Inflorescence of spicate main branches, or a false spike, with spikelets on contracted axes, or a single raceme; spicate ("a single spikelike raceme"). Primary inflorescence branches 1–5 (of pectinate ‘racemes’). Inflorescence with axes ending in spikelets (but the lower glume of the terminal spikelet simulating a rachis extension). Rachides hollowed. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary (ostensibly, by abortion), or paired; secund; sessile and pedicellate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations. The ‘shorter’ spikelets hermaphrodite, or female-only, or sterile. The ‘longer’ spikelets hermaphrodite.

Female-fertile spikelets. Spikelets 6–10 mm long; abaxial; compressed laterally; falling with the glumes. The upper floret conspicuously stipitate (its callus with narrow wings or scars at the base of the lemma). Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; very unequal to more or less equal; (the longer) long relative to the adjacent lemmas; lateral to the rachis; pointed; awned to awnless (acute to shortly awned); carinate to non-carinate (the nerves forming ribs); similar (tuberculate-bristly). Lower glume tuberculate (with tubercle based bristles); 3–9 nerved. Upper glume 7–9 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate; male. The proximal lemmas awnless; 5 nerved; decidedly exceeding the female-fertile lemmas; similar in texture to the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas similar in texture to the glumes to decidedly firmer than the glumes; smooth; not becoming indurated; entire; blunt; awnless; hairless; glabrous; non-carinate; having the margins inrolled against the palea; with a clear germination flap; 3–5 nerved. Palea present; relatively long; 2-nerved; keel-less. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small. Hilum long-linear.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (fairly thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present (large); panicoid-type; 75–90 microns long, or (48–)51–60(–63) microns long (in E. gracilis); 9–12 microns wide at the septum, or (7.5–)8.4–9(–9.3) microns wide at the septum (E. gracilis). Microhair total length/width at septum 5.3–8.7. Microhair apical cells 39–48 microns long, or 27–36 microns long (E. gracilis). Microhair apical cell/total length ratio 0.5–0.7. Stomata common; 57–63 microns long, or (39–)45–48(–51) microns long (in E. gracilis). Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; not paired; not silicified. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; cross shaped and dumb-bell shaped.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma; Isachne-type. Leaf blade adaxially flat. Midrib with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.

Phytochemistry. Leaves without flavonoid sulphates (1 species).

Cytology. Chromosome base number, x = 9. 2n = 60.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paspaleae; Paspalinae. 6 species.

Distribution, phytogeography, ecology. Central & South America, 1 Madagascar.

Helophytic, or mesophytic; species of open habitats. Savanna.

References, etc. Leaf anatomical: this project.


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Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 13th November 2017. delta-intkey.com/grass’.

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