The grass genera of the world
Habit, vegetative morphology. Culms 50–60 cm high; herbaceous. Plants unarmed. Sheath margins free. Sheaths basally inflated. Leaf blades ovate to elliptic (and attenuate); broad; 15–17 mm wide (and 8–9 cm long); cordate (or subcordate), or not cordate, not sagittate; without cross venation (or these not mentioned). Ligule membranous, long-pilose.
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.
Inflorescence. Inflorescence of spicate main branches (of dorsiventral false spikes at the apex of the culm); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes racemes; solitary; with substantial rachides; persistent. Spikelets paired (seemingly); secund (the rachis dorsiventral); biseriate (the pairs in two rows); sessile and pedicellate (the hermaphrodite spikelets short-pedicelled); consistently in long-and-short combinations; in pedicellate/sessile combinations. Pedicels of the pedicellate spikelets free of the rachis. The shorter spikelets sterile (reduced to a glume). The longer spikelets hermaphrodite.
Female-sterile spikelets. The sterile spikelets sessile, reduced to one dorsally compressed glume.
Female-fertile spikelets. Spikelets unconventional (because of the extra glume, representing the sessile spikelet); 2.2–2.5 mm long; abaxial; strongly compressed laterally; falling with the glumes. Rachilla terminated by a female-fertile floret.
Glumes two; more or less equal; about equalling the spikelets, or exceeding the spikelets; long relative to the adjacent lemmas; dorsiventral to the rachis; hairless; without conspicuous tufts or rows of hairs; awned to awnless; very dissimilar (G1 subulate, and subaristate, G2 obtuse and muticate). Lower glume relatively smooth; 1 nerved. 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; paleate; male. The proximal lemmas saccate; awnless; decidedly exceeding the female-fertile lemmas; decidedly firmer than the female-fertile lemmas (cartilaginous, umbonate).
Female-fertile florets 1. Lemmas less firm than the glumes; not becoming indurated; white in fruit (whitish); awnless, or mucronate (?); hairless; apically subgibbous; having the margins lying flat on the palea. Palea present; not indurated (thin). Stamens 6. Ovary apically glabrous. Stigmas 2.
Fruit, embryo and seedling. Fruit small (1.5 mm long); compressed laterally (and subtriangular).
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type. Stomata common. Intercostal short-cells common. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae (Boivinelleae). Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Boivinellinae. 2 species.
Distribution, phytogeography, ecology. Madagascar.
References, etc. Morphological/taxonomic: Camus 1925b; Bosser 1965.
Special comments. Fruit data wanting. Illustrations. • B. sclerioides: Camus, Bull Soc. Bot. Fr. (1925)
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’.