The grass genera of the world
From the Greek leptos (thin) and aspis (a round shield), alluding to the lemma of the female spikelet.
Habit, vegetative morphology. Perennial; rhizomatous. The flowering culms leafy. Culms 30–100 cm high; herbaceous. Culm nodes glabrous. Culm internodes solid. Leaves not basally aggregated; non-auriculate; without auricular setae. Leaf blades broad; pseudopetiolate; pinnately veined (the laterals slanting obliquely from the midrib); cross veined; persistent; rolled in bud. Ligule present (short); a fringed membrane. Contra-ligule absent.
Reproductive organization. Plants monoecious with all the fertile spikelets unisexual; without hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; female-only and male-only. The male and female-fertile spikelets mixed in the inflorescence. The spikelets overtly heteromorphic (the male spikelets smaller).
Inflorescence. Inflorescence paniculate; open (with 1–3 primary branches at each of (1-)3–7 nodes). Rachides hollowed, or flattened, or winged, or neither flattened nor hollowed, not winged. Inflorescence spatheate (the spikelet branchlets often subtended by bracts), or espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate (the female pedicels filiform, not clavate); consistently in long-and-short combinations. The shorter spikelets female-only. The longer spikelets male-only.
Female-sterile spikelets. Male spikelets smaller than the females, narrower, the floret with 6 stamens, the anthers non-penicillate, the floret caducous. The male spikelets with glumes; 1 floreted. The lemmas awnless, or mucronate (?). Male florets 6 staminate.
Female-fertile spikelets. Spikelets compressed dorsiventrally; disarticulating above the glumes. Rachilla terminated by a female-fertile floret; hairless. Hairy callus absent.
Glumes two, or several (often 3); minute, or relatively large; more or less equal; shorter than the adjacent lemmas; pointed (cuspidate); awnless; similar (herbaceous, persistent). Lower glume 1–3 nerved. Upper glume 1–3 nerved.
Female-fertile florets 1. Lemmas inflated, sacciform, cochleate, their margins joined to form utricles which are closed save for a lateral pore from which the stigmas emerge; decidedly firmer than the glumes; becoming indurated; awnless, or mucronate (?); hairy; non-carinate; 7–9 nerved. Palea present (enclosed within the lemma, linear); apically notched (bidentate); indurated (when mature); 2-nerved; 2-keeled. Lodicules present (but small), or absent; when present, 2, or 3; free; membranous; glabrous; not toothed. Stamens 0 (and no staminodes, or in L. banksii, 6 minute staminodes present at the base of the ovary). Ovary glabrous. Styles fused (into one). Stigmas 3.
Fruit, embryo and seedling. Fruit free from both lemma and palea. Pericarp fused. Endosperm hard.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata absent or very rare (in places), or common. Subsidiaries tall dome-shaped to triangular. Guard-cells overlapped by the interstomatals to overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies small, horizontally-elongated smooth (a few, almost), or panicoid-type (predominantly, but much reduced); seemingly smoothed out dumb-bell shaped and nodular; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with adaxial palisade (of cubical cells and an abaxial one of tall cells); traversed by columns of colourless mesophyll cells; without arm cells; with fusoids. The fusoids external to the PBS. Leaf blade nodular in section; with the ribs more or less constant in size. Midrib conspicuous; having complex vascularization; with colourless mesophyll adaxially. Bulliforms not present in discrete, regular adaxial groups (ill defined or absent). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures. Sclerenchyma all associated with vascular bundles.
Special diagnostic feature. Having female spikelets, with shell- or urn-shaped lemmas which are closed save for an apical pore.
Cytology. Chromosome base number, x = 12. 2n = 24. 2 ploid.
Taxonomy. Bambusoideae; Oryzodae; Phareae.
Distribution, ecology, phytogeography. 5 species; tropical west Africa, Mascarene Is., Ceylon, Fiji, New Guinea, Australia. Shade species. In forest.
Paleotropical and Australian. African, Madagascan, Indomalesian, Polynesian, and Neocaledonian. Saharo-Sindian, Sudano-Angolan, and West African Rainforest. Indian, Indo-Chinese, Malesian, and Papuan. Fijian. North and East Australian. Sahelo-Sudanian, Somalo-Ethiopian, and South Tropical African. Tropical North and East Australian.
References, etc. Morphological/taxonomic: Judziewicz 1984. Leaf anatomical: Metcalfe 1960; this project.
Special comments. Fruit data wanting.
Illustrations. • Abaxial epidermis of leaf blade (L. banksii)
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, summaries of attributes within groups of taxa, geographical distribution, classification, and species sampled for anatomy.
Cite this publication as: ‘Watson, L., 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: 18th December 2012. http://delta-intkey.com’.