The grass genera of the world
Habit, vegetative morphology. Annual; loosely caespitose, or decumbent (rarely, rooting at the nodes). Culms 13–130 cm high; herbaceous; branched above, or unbranched above. Culm nodes glabrous. Culm internodes solid. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate, or auriculate (at the base of the blade). Leaf blades lanceolate to ovate; broad; 4–15 mm wide; cordate, or not cordate, not sagittate; flat, or rolled; without abaxial multicellular glands; without cross venation; persistent. Ligule a fringed membrane; truncate; 0.3–0.4 mm long. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence of spicate main branches; contracted (to about 20 cm long, the thin spicate laterals appressed). Primary inflorescence branches 10–20 (or more -i.e. many). Rachides neither flattened nor hollowed, not winged (very slender). Inflorescence espatheate; not comprising partial inflorescences and foliar organs. The racemes spikelet bearing to the base (or nearly so). Spikelet-bearing axes persistent. Spikelets solitary; secund; biseriate; subsessile.
Female-fertile spikelets. Spikelets 5–11 mm long; lanceolate; compressed laterally; disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairy; the rachilla extension with incomplete florets. Hairy callus present (slender). Callus short; pointed.
Glumes two; relatively large; very unequal; shorter than the spikelets; (the upper) long relative to the adjacent lemmas; hairless; scabrous (on the keels); pointed (G1 acuminate-mucronate); awnless; carinate; similar (reddish, subhyaline, very narrow). Lower glume 0.5–0.75 times the length of the upper glume; shorter than the lowest lemma; 1 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awned. Spikelets without proximal incomplete florets.
Female-fertile florets 6–12. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (thin); smooth; not becoming indurated; incised; 4 lobed (minutely 4 toothed); not deeply cleft; awned. Awns 1; median (the midnerve excurrent); from a sinus; non-geniculate (very slender); hairless (scabrid); about as long as the body of the lemma to much longer than the body of the lemma; entered by one vein. Lemmas hairy (pubescent below the middle, the edges ciliate); carinate; without a germination flap; 3 nerved; with the nerves non-confluent. Palea present (linear-oblong); relatively long, or conspicuous but relatively short; entire; awnless, without apical setae; textured like the lemma; not indurated (thin); 2-nerved; 2-keeled. Palea keels wingless; hairy. Lodicules present; 2; free; fleshy; glabrous; not toothed; not or scarcely vascularized. Stamens 2, or 3. Anthers 0.4 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; brown.
Fruit, embryo and seedling. Fruit free from both lemma and palea (tightly embraced); small (to 1 mm long); linear; obtusely triquetrous. Hilum short. Pericarp fused. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal (more conspicuous intercostally). Intercostal papillae over-arching the stomata; several per cell. Mid-intercostal long-cells rectangular; having markedly sinuous walls (coarsely so). Microhairs present; elongated; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 18–20 microns long. Microhair basal cells 12–14 microns long. Microhair apical cells 4–8 microns long. Microhair apical cell/total length ratio 0.3. Stomata common. Subsidiaries high dome-shaped to triangular. Intercostal short-cells common; mostly not paired (but with a few pairs and threes); not silicified. Intercostal silica bodies absent. Costal short-cells conspicuously in long rows (the files often interrupted by prickles). Costal silica bodies present in alternate cell files of the costal zones; panicoid-type; mostly dumb-bell shaped (sometimes short); not sharp-pointed.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheath outlines even. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions absent. PCR cell chloroplasts centripetal. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans (mostly), or associated with colourless mesophyll cells to form deeply-penetrating fans (a few only, in the material seen). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with most bundles). Sclerenchyma all associated with vascular bundles. The lamina margins without fibres.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae; Gymnopogoninae. 1 species (L. vulpiastrum).
Distribution, phytogeography, ecology. East and southern Africa.
Economic aspects. Important native pasture species: L. vulpiastrum.
References, etc. Leaf anatomical: Metcalfe 1960; studied by us; photos provided by R.P. Ellis.
Illustrations. • L. vulpiastrum: Wood & Evans (1908), Natal Plants 5. • General aspect (L. vulpiastrum): Gibbs Russell et al., 1990
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: 11th December 2017. delta-intkey.com/grass’.