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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Cephalostachyum Munro

~ Schizostachyum

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; studied by us - C. pergracile Munro.

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)

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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.’.