Cephalostachyum Munro
Sometimes referred to Schizostachyum
Habit, vegetative morphology. Perennial. The flowering culms leafy. Culms 300–1300 cm high; woody and persistent; to 7.5 cm in diameter; scandent, or not scandent; branched above. 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).
Reproductive organization. Plants bisexual, 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 12–25 mm long; 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; 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 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.
Taxonomy. Bambusoideae; Bambusodae; Bambuseae.
Distribution, ecology, phytogeography. 12 species; Indomalaya, Madagascar.
Paleotropical. Madagascan and Indomalesian. Indian, Indo-Chinese, and Malesian.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • Spikelet cluster. Cephalostachyum pergracile. • Pseudospikelets. Cephalostachyum percgracile. • Flower. Cephalostachyum pergracile. • Gynoecium. Cephalostachyum pergracile.
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).
