The grass genera of the world
Habit, vegetative morphology. Annual. Culms 8–16 cm high; herbaceous; branched above. Culm nodes hairy, or glabrous. Leaves non-auriculate. Leaf blades linear; narrow; 3–4 mm wide (to 4 cm long); not pseudopetiolate; without cross venation. Ligule an unfringed membrane; 1 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant (spikelet pairs homomorphic and sterile at the base of the raceme, heteromorphic heterogamous pairs above); hermaphrodite and male-only, or hermaphrodite and sterile; overtly heteromorphic (the pedicelled and basal spikelets awnless); in both homogamous and heterogamous combinations (there being homomorphic, sterile pairs at the base of the raceme).
Inflorescence. Inflorescence of paired racemes, or these solitary (in B. borii); digitate, or non-digitate (B. borii). Primary inflorescence branches 1–2. Inflorescence spatheate (the raceme base(s) embraced by a spatheole); a complex of partial inflorescences and intervening foliar organs. Spikelet-bearing axes racemes (about 6-noded); solitary (B. borii), or paired; with very slender rachides (the raceme bases terete); disarticulating; disarticulating at the joints. Articles linear (slightly expanded above); without a basal callus-knob; not appendaged; disarticulating obliquely; densely long-hairy (down one side). Spikelets paired; sessile and pedicellate; consistently in long-and-short combinations; in pedicellate/sessile combinations. Pedicels of the pedicellate spikelets free of the rachis. The shorter spikelets hermaphrodite, or sterile (reduced to glumes, at the base of the raceme). The longer spikelets sterile (and awnless).
Female-sterile spikelets. The male spikelets with glumes. The lemmas awnless.
Female-fertile spikelets. Spikelets 7–20 mm long; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present. Callus short; blunt.
Glumes two; very unequal (G2 shorter, excluding the awn); (the longer) long relative to the adjacent lemmas; hairless; awned (G2, from a sinus); very dissimilar (G1 narrow, pointed and 2-keeled above, awnless, G2 trilobed and long-awned from a deep apical sinus). Lower glume two-keeled (inrolled below, but asymmetrically keel-winged above); convex on the back to flattened on the back; not pitted; relatively smooth; 2 nerved (without intercarinal nerves). Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1. The proximal lemmas awnless; 2 nerved; exceeded by the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas less firm than the glumes; incised; not deeply cleft (i.e. to less than a quarter); awned. Awns 1; median; from a sinus; geniculate; hairless; much longer than the body of the lemma. Lemmas hairless; non-carinate; without a germination flap. Palea present; conspicuous but relatively short; awnless, without apical setae; not indurated. Lodicules present; 2; free; glabrous.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (abundant); costal and intercostal. Intercostal papillae over-arching the stomata; several per cell (usually in a single row of 2–6 per cell, thick walled, circular, symmetrical to asymmetrical). Long-cells fairly markedly different in shape costally and intercostally (the costals narrower); of similar wall thickness costally and intercostally (fairly thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls (the sinuosity coarse). Microhairs present; more or less spherical (sic); clearly two-celled; chloridoid-type (i.e., most unexpected). Stomata common. Subsidiaries papillate (each with a pair of inwardly directed papillae, one from each side); dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. No macrohairs or prickles seen. Costal short-cells conspicuously in long rows. Costal silica bodies present and well developed; panicoid-type; dumb-bell shaped and nodular.
Transverse section of leaf blade, physiology. C4. The anatomical organization conventional. XyMS. Leaf blade adaxially flat. Midrib conspicuous; having a conventional arc of bundles (a large median, with several smaller bundles on either side); with colourless mesophyll adaxially. The lamina symmetrical on either side of the midrib. Bulliforms not present in discrete, regular adaxial groups (the epidermis mainly consisting of large, bulliform-like cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles, even the tiniest); nowhere forming figures (the fibre groups everywhere small, save the one abaxial to the median bundle). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae. Soreng et al. (2015): Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae. 3 species.
Distribution, phytogeography, ecology. India.
Species of open habitats. Dry shallow soils.
References, etc. Morphological/taxonomic: Bor 1948. Leaf anatomical: this project.
Special comments. Fruit 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’.