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The grass genera of the world

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

Elytrostachys McClure

Habit, vegetative morphology. Scrambling, sympodial perennial. The flowering culms leafy. Culms woody and persistent; scandent to not scandent (‘culms self-supporting below, typically weak and pendulous or clambering above’); branched above. Buds from which the primary culm branches arise 1. Primary branches 11–20; clumped. The branching dendroid. Culm leaf sheaths present; persistent; where recorded, not conspicuously auriculate. Culm leaves with conspicuous blades. Culm internodes hollow. Rhizomes pachymorph. Plants unarmed. Leaves not basally aggregated; with auricular setae. Leaf blades broad; pseudopetiolate; cross veined, or without cross venation; disarticulating from the sheaths; rolled in bud. Contra-ligule absent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. Viviparous.

Inflorescence. Inflorescence indeterminate; with pseudospikelets; of pseudospikelet clusters terminating leafy or leafless axes; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelet-bearing axes paniculate to capitate; persistent. Spikelets not secund.

Female-fertile spikelets. Spikelets unconventional; lanceolate; compressed laterally (?); disarticulating above the glumes; with a distinctly elongated rachilla internode above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.

Glumes two (in accordance with the definition of glumes applied here); very unequal; shorter than the adjacent lemmas; awnless; similar. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets without proximal incomplete florets.

Female-fertile florets 1, or 2. Lemmas not becoming indurated; entire; pointed, or blunt; awnless, or mucronate (?). Palea present; relatively long; awnless, without apical setae; not indurated; 2-keeled (sulcate). Palea keels wingless. Lodicules present; 3; free; membranous; ciliate; not toothed; heavily vascularized. Stamens 6. Ovary apically glabrous; with a conspicuous apical appendage. The appendage broadly conical, fleshy. Styles fused (the ovary attenuate to the stigmas). Stigmas 2.

Fruit, embryo and seedling. Fruit longitudinally grooved. Hilum long-linear. Pericarp thick and hard (leathery, thickened at the apex).

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (and the intercostal zones with broad stomatal and astomatal bands). Papillae present; costal and intercostal. Intercostal papillae over-arching the stomata (almost covering them); several per cell (mostly with a single median row of 6–10 circular or somewhat bifurcated papillae per long-cell). Long-cells markedly different in shape costally and intercostally (the costals narrower); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; panicoid-type; 57–60 microns long; 6–6.3 microns wide at the septum. Microhair total length/width at septum 9.5–10. Microhair apical cells 36–40.5 microns long. Microhair apical cell/total length ratio 0.6–0.7. Stomata common; 21–24 microns long. Subsidiaries triangular. Intercostal short-cells common (in the astomatal regions); not paired (solitary); not silicified. Macrohairs present costally, a few prickles present costally and intercostally. Crown cells absent. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies scarce, tall-and-narrow to crescentic.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat. Midrib conspicuous; having complex vascularization (one large bundle, and assorted small ones). The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups (with a large group in the middle of each intercostal zone); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (all the bundles with a conspicuous ‘anchor’). Sclerenchyma not all bundle-associated (there being adaxial hypodermal fibres lining the sides of the bulliforms, but no abaxial groups opposite them). The ‘extra’ sclerenchyma in adaxial groups; adaxial-hypodermal, contiguous with the bulliforms.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Arthrostylidiinae. 2 species.

Distribution, phytogeography, ecology. South America: Honduras to Venezuela.

Mesophytic; glycophytic. Rain forest.

References, etc. Leaf anatomical: this project.

Illustrations. • E. clavigera: McClure, New World Bamboos (1973)


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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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