Echinolaena Desv.
Excluding Chasechloa
Habit, vegetative morphology. Annual, or perennial; rhizomatous to stoloniferous. Culms herbaceous; branched above. 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, 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 single 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; 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; not crested; 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 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.
Taxonomy. Panicoideae; Panicodae; Paniceae.
Distribution, ecology, phytogeography. 6 species; Central & South America, 1 Madagascar. Helophytic, or mesophytic; species of open habitats. Savanna.
Paleotropical and Neotropical. Madagascan. Caribbean, Central Brazilian, and Andean.
References, etc. Leaf anatomical: this project.
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).