The grass genera of the world
Including Lasiotrichos Lehm.
Habit, vegetative morphology. Perennial (usually), or annual (rarely, in desert areas); caespitose. Culms 5–117 cm high; herbaceous; unbranched above. Culm nodes glabrous. Culm internodes hollow. Plants unarmed. Young shoots intravaginal. Leaves mostly basal; non-auriculate. Leaf blades long linear; narrow; 2–5 mm wide; flat, or folded; without abaxial multicellular glands; not pseudopetiolate; without cross venation; persistent. Ligule a fringe of hairs; 0.1–0.7 mm long (and the base of the blade sometimes hairy above the ligule).
Reproductive organization. Plants bisexual, all 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 lowest sometimes barren). Apomictic (peculiarly so), or reproducing sexually (?).
Inflorescence. Inflorescence a single raceme, or paniculate (to 12 cm long); densely contracted; more or less ovoid to spicate; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; pedicellate; imbricate.
Female-fertile spikelets. Spikelets 4–7 mm long; strongly compressed laterally; falling with the glumes (disarticulating from persistent pedicels); not disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; tough; the rachilla extension with incomplete florets. Callus of spikelet blunt.
Glumes two; more or less equal; exceeding the spikelets; long relative to the adjacent lemmas; hairy (with straight hairs on the keels and margins); pointed; awned, or awnless (shortly awned or mucronate); carinate (ciliate on keel); similar (narrow, folded, thin). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1–3; merely underdeveloped (male or rudimentary). Spikelets without proximal incomplete florets.
Female-fertile florets 1. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (rather firmly membranous); not becoming indurated; entire; pointed, or blunt; mucronate (via the excurrent median nerve); hairy (long-ciliate on the keels and margins), or hairless (F. sesleriformis); carinate; without a germination flap; (3–)5 nerved, or 7 nerved; with the nerves confluent towards the tip. Palea present; relatively long; apically notched; awnless, without apical setae; textured like the lemma; basally indurated to not indurated; 2-nerved; 2-keeled. Palea keels wingless. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers 2–2.5 mm long; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; ellipsoid; somewhat compressed laterally. Embryo with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.
Ovule, embryology. Micropyle oblique. Outer integument extensive, being absent only from the micropylar region; two cells thick at the micropylar margin. Inner integument continuous, the micropyle constricted; thickened around the micropyle. Synergids not haustorial; without large, globular starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (but the costals smaller); of similar wall thickness costally and intercostally (quite thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; chloridoid-type to Enneapogon-type (suggestive of a small version of the latter). Microhair apical cell wall thinner than that of the basal cell but not tending to collapse to of similar thickness/rigidity to that of the basal cell. Microhairs 52.5–67 microns long. Microhair basal cells 33–36 microns long. Microhairs 9–10.5 microns wide at the septum. Microhair total length/width at septum 5.1–6.3. Microhair apical cells 18–24 microns long. Microhair apical cell/total length ratio 0.34–0.44. Stomata common; 24–27 microns long. Subsidiaries triangular. Guard-cells overlapped by the interstomatals (very slightly). Intercostal short-cells common; in cork/silica-cell pairs (and some solitary); silicified. Intercostal silica bodies imperfectly developed; rounded, or saddle shaped, or crescentic, or cubical. Costal short-cells predominantly paired. Costal silica bodies present throughout the costal zones; saddle shaped (a round version, predominating everywhere), or rounded (a few, merging with the saddles), or crescentic (a few, plus a few more or less cubical).
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 both abaxially and adaxially. PCR sheath extensions absent. PCR cell chloroplasts centripetal. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells. Leaf blade nodular in section to adaxially flat; with the ribs more or less constant in size (somewhat larger over large bundles). Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (these incorporated in the traversing columns of colourless cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with the primaries); forming figures (anchors, but only in the primaries: the smaller bundles with strands only). Sclerenchyma all associated with vascular bundles. The lamina margins with fibres (large).
Cytology. Chromosome base number, x = 10. 2n = 20 and 40. 2 and 4 ploid.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Eragrostideae; Unioliinae. 2 species.
Distribution, phytogeography, ecology. Southern Africa, Afghanistan and Arabia.
Helophytic, or mesophytic, or xerophytic; species of open habitats; glycophytic.
Rusts and smuts. Smuts from Ustilaginaceae. Ustilaginaceae Ustilago.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Special comments. Fruit data wanting. Illustrations. • F. africana: Hook. Ic. Pl. 14 (1880–82). • General aspect (F. africana): 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: 13th November 2017. delta-intkey.com/grass’.