The grass genera of the world
Habit, vegetative morphology. Annual; with solitary, prostrate culms rooting at the lower nodes. Culms herbaceous; decumbent; unbranched above. Culm nodes glabrous. Leaf blades linear to lanceolate; narrow; 1–2 cm long, 1.4–3.5 mm wide; pseudopetiolate. Ligule an unfringed membrane; 0.5–0.7 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and sterile; overtly heteromorphic (the sterile ones reduced to pedicels); all in heterogamous combinations.
Inflorescence. Inflorescence of spicate main branches; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes racemes; the spikelet-bearing axes with more than 10 spikelet-bearing articles (with 14 spikelet pairs on each); disarticulating; disarticulating at the joints. Articles linear (about 0.9 mm long, the tip crateriform). Spikelets consistently in long-and-short combinations (? - available description ambiguous); in pedicellate/sessile combinations. Pedicels of the pedicellate spikelets free of the rachis. The shorter spikelets hermaphrodite. The longer spikelets sterile (reduced to their pedicels).
Female-sterile spikelets. Rachilla of male spikelets terminated by a male floret.
Female-fertile spikelets. Spikelets 1.7 mm long; oblong; compressed laterally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present. The callus hairs white.
Glumes two; more or less equal; about equalling the spikelets; long relative to the adjacent lemmas; awned (the upper with a 30 mm awn); non-carinate; very dissimilar (the lower oblong, awnless, obtuse or emarginate, cartilaginous, the upper oblong and long-awned). Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets according to the descriptions seen, without proximal incomplete florets.
Female-fertile florets 2 (different - the lower muticous, the upper awned). Lemmas less firm than the glumes; not becoming indurated (membranous); apically entire (the lower), or incised (the upper); long awned (the upper), or awnless (the lower). Awns 1; median; from a sinus; geniculate; much longer than the body of the lemma (30–35 mm long). Awn bases twisted. Lemmas hairless; non-carinate; having the margins lying flat on the palea. Palea present to absent; if present, relatively long to very reduced (0.7 mm long in the lower floret); awned.
Classification. Watson & Dallwitz (1994): not described separately. Soreng et al. (2015): Panicoideae; Andropogonodae; Andropogoneae; Saccharinae. 1 species (V. sagaingensis).
Distribution, phytogeography, ecology. Tropical Asia, Indo-China.
References, etc. Morphological/taxonomic: Grassbase (2016).
Special comments. The Clayton et al. generic and species descriptions are hopelessly confused re. spikelet morphology (q.v.), so the current compilation is unreliable. Anatomical data wanting.
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’.