The grass genera of the world
Habit, vegetative morphology. Perennial. The flowering culms leafy. Culms 300–1300 cm high; woody and persistent; to 10 cm in diameter; scandent, or not scandent; branched above. Primary branches where recorded, 4–10. The branching dendroid. Culm leaf sheaths present; commonly conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades lanceolate, or ovate, or triangular. Culm internodes hollow. Plants unarmed. Young shoots extravaginal. Leaves not basally aggregated; with auricular setae, or without auricular setae. Leaf blades linear-lanceolate to ovate-lanceolate (acuminate); broad; 15–100 mm wide (and 2.5–20 cm long); not cordate, not sagittate (base rounded or cuneate); flat; pseudopetiolate; without cross venation (but sometimes abaxially with pellucid dots simulating veinlets); disarticulating from the sheaths; rolled in bud. Ligule present (long). Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite, male-only, and sterile (perfect and variously imperfect or comprising empty glumes); overtly heteromorphic.
Inflorescence. Inflorescence indeterminate; with pseudospikelets; a terminal, globose head or an interrupted spike of heads; non-digitate; spatheate (the heads bracteate); a complex of partial inflorescences and intervening foliar organs. Spikelet-bearing axes capitate; persistent. Spikelets not secund.
Female-fertile spikelets. Spikelets unconventional; 12–25 mm long; lanceolate (nearly always), or lanceolate to ovate (C. mindorense); compressed laterally to not noticeably compressed; disarticulating above the glumes; with conventional internode spacings, or with a distinctly elongated rachilla internode above the glumes. Rachilla conspicuously prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets, or naked (terminated by a tiny aborted floret, in the material seen).
Glumes two to several; shorter than the adjacent lemmas; free; pointed; usually awned (terminally); non-carinate; similar (broad, chaffy, many-nerved). Lower glume 11–13 nerved. Upper glume 11–15 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets when detectable, distal to the female-fertile florets. The distal incomplete florets when detected, 1; merely underdeveloped (the rachilla prolongation terminated by a tiny aborted floret, in the material seen).
Female-fertile florets 1. Lemmas ovate-lanceolate; less firm than the glumes to similar in texture to the glumes; not becoming indurated; entire; pointed; awnless (e.g. C. chapeleri), or awned. Awns when present, 1; median; apical; non-geniculate; hairless; much shorter than the body of the lemma (and shorter than glume awns); entered by several veins. Lemmas hairy; non-carinate; without a germination flap; 14–18 nerved (in the species seen); with the nerves non-confluent. Palea present; relatively long; convolute around the flower, or not convolute; apically notched; bimucronate or awned; textured like the lemma; not indurated; several nerved (about 9–13); 2-keeled (sulcate between the close keels). Palea back hairy. Palea keels wingless; hairy. Lodicules present; 3; free; membranous; ciliate (or papillose); not toothed; heavily vascularized. Stamens 6. Anthers 4.5–5 mm long (in the material seen); penicillate, or not penicillate; with the connective apically prolonged, or without an apically prolonged connective. Ovary apically glabrous; with a conspicuous apical appendage. The appendage long, stiff and tapering. Styles fused; completely fused (the ovary apex attenuate into one long style). Stigmas 2, or 3 (short).
Fruit, embryo and seedling. Fruit free from both lemma and palea; longitudinally grooved, or not grooved. Pericarp thick and hard (crustaceous); free. Endosperm containing compound starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal papillae over-arching the stomata; several per cell. Intercostal zones exhibiting many atypical long-cells. Mid-intercostal long-cells having markedly sinuous walls. Microhairs present; panicoid-type (the cells of equal length); 64–69 microns long; 5–9 microns wide at the septum. Microhair total length/width at septum 6.1–11.9. Microhair apical cells 25.5–33 microns long. Microhair apical cell/total length ratio 0.39–0.5. Stomata common (obscured by the papillae); 15–21 microns long. Intercostal short-cells common. Costal silica bodies poorly developed (in the material seen); oryzoid (?).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with arm cells; with fusoids. Leaf blade adaxially flat (except on one side of midrib). Midrib conspicuous; having complex vascularization. The lamina distinctly asymmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures.
Cytology. Chromosome base number, x = 12. 2n = 72. 6 ploid.
Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Melocanninae. 12 species.
Distribution, phytogeography, ecology. Indomalaya, Madagascar.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • C. capitatum, C. fuchsianum (= latifolium), C. virgatum: Camus (913).. • Abbreviations for Camus (1913) figures. • Spikelet cluster (C. pergracile). • Pseudospikelets (C. pergracile). • Flower (C. pergracile). • Gynoecium (C. pergracile)
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’.