The grass genera of the world
Type species: Type: L. repens (Forst.) R.Br.
Including Lepiurus Dum., Leptocercus Raf., Monerma P. Beauv.
Habit, vegetative morphology. Perennial; stoloniferous and caespitose. Culms 10–60 cm high; herbaceous; branched above, or unbranched above. The branching simple. Culm nodes glabrous. Culm internodes solid. Leaves not basally aggregated; non-auriculate. Leaf blades linear to linear-lanceolate; narrow; not setaceous; flat, or rolled (involute); without abaxial multicellular glands; without cross venation; persistent. Ligule an unfringed membrane.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence a single spike (almost cylindrical, the joints striate). Rachides hollowed. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes with substantial rachides; disarticulating; disarticulating at the joints. Articles non-linear (hollowed to receive the spikelets); not appendaged; disarticulating transversely, or disarticulating obliquely; glabrous. Spikelets solitary; not secund; distichous; sessile.
Female-fertile spikelets. Spikelets 3–15(–20) mm long; adaxial; compressed dorsiventrally; falling with the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes one per spikelet (the lower usually missing), or two; very unequal; (the upper) long relative to the adjacent lemmas; free; dorsiventral to the rachis; pointed; awnless, or awned (the G2 sometimes tapered into a short awn); very dissimilar (the lower, if present, reduced to a minute triangular scale, the upper exceeding the spikelet, thickened, with rows of minute bristles on the back). Lower glume 1 nerved. Upper glume 5–12 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.
Female-fertile florets 1–2. Lemmas less firm than the glumes (membranous); not becoming indurated; entire; pointed; awnless; hairy (minutely so, at the base), or hairless (glabrous); non-carinate; 3 nerved. Palea present (lanceolate); relatively long; not indurated (hyaline); 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit free from both lemma and palea; ellipsoid; compressed dorsiventrally. Hilum short. Pericarp free. Embryo large; not waisted. Endosperm hard; containing only simple starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae not over-arching the stomata; several per cell (finger-like). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (fairly thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; more or less spherical; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs (22.5–)24–25.5(–28.5) microns long; (9.6–)10.5–11.4(–13.8) microns wide at the septum. Microhair total length/width at septum 1.6–2.7. Microhair apical cells (7.5–)9–11(–12) microns long. Microhair apical cell/total length ratio 0.29–0.47. Stomata common; 19.5–22.5 microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs, or not paired; silicified (a few), or not silicified. Intercostal silica bodies imperfectly developed; tall-and-narrow. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present in alternate cell files of the costal zones; saddle shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheath outlines uneven, or even. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions absent. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells, or not traversed by colourless columns. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib conspicuous; having a conventional arc of bundles; with colourless mesophyll adaxially (adaxial colourless tissue sometimes also present in other parts of the blade). Bulliforms present in discrete, regular adaxial groups; in simple fans, or in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans (sometimes linked with girders of colourless cells). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.
Cytology. 2n = 14, 18, 26, 36, 52, and 54.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae; Eleusininae. About 8 species.
Distribution, phytogeography, ecology. Coastal east Africa, Madagascar, to Australia, & Polynesia.
Xerophytic; species of open habitats; halophytic. Sandy beaches and coastal hinterland, usually good sandbinders.
Hybrids. Lepturopetium (q.v.) may be an intergeneric hybrid involving Lepturus as one parent.
Rusts and smuts. Rusts Puccinia.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • General aspect, inflorescence (L. repens): Gibbs Russell et al., 1990. • Inflorescence (L. xerophyllus). • L. repens, abaxial epidermis of leaf blade: this project
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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 or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.
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’.