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The grass genera of the world

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

Oreobambos K. Schum.

~ Dendrocalamus

Habit, vegetative morphology. Arborescent perennial. The flowering culms leafy. Culms 450–1800 cm high; woody and persistent; to 10 cm in diameter; branched above. Primary branches 2, or 3; in an irregular line. The branching dendroid. Culm nodes glabrous. Culm leaf sheaths present; not conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades linear. Culm internodes hollow. Pluricaespitose. Rhizomes pachymorph. Plants unarmed. Leaves not basally aggregated; without auricular setae. Leaf blades lanceolate to elliptic; broad; 25–60 mm wide; pseudopetiolate; without cross venation; disarticulating from the sheaths; rolled in bud.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. Not viviparous.

Inflorescence. Inflorescence indeterminate; with pseudospikelets; a false spike, with spikelets on contracted axes (with involucrate, cupuliform clusters of pseudospikelets on bare branches); spatheate (each cluster subtended by a deciduous spathe, and associated with broad, leathery bracts). Spikelet-bearing axes very much reduced (the spikelet clusters of 3 or more spikelets or pseudo-spikelets each subtended by a pair of leafy bracts); persistent. Spikelets associated with bractiform involucres.

Female-fertile spikelets. Spikelets unconventional; 12–15 mm long; lanceolate; compressed laterally to not noticeably compressed; falling with the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension naked. Hairy callus absent.

Glumes one per spikelet; long relative to the adjacent lemmas; hairless (papery); glabrous; not pointed; awnless; non-carinate. Upper glume 11–18 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 2 (subequal). Lemmas similar in texture to the glumes to decidedly firmer than the glumes (papery to thinly leathery); not becoming indurated; entire; blunt; awnless; hairless; glabrous; without a germination flap; 11–23 nerved. Palea present; relatively long; not convolute; apically notched; awnless, without apical setae; not indurated; several nerved (5–11); 2-keeled. Lodicules absent. Stamens 6. Anthers not penicillate; with the connective apically prolonged. Ovary apically hairy; with a conspicuous apical appendage. The appendage broadly conical, fleshy. Styles fused (into one). Stigmas 1.

Fruit, embryo and seedling. Pericarp thick and hard; free (and with a crustaceous, hairy apical appendage).

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal papillae over-arching the stomata; several per cell. Long-cells similar in shape costally and intercostally; differing markedly in wall thickness costally and intercostally. Mid-intercostal long-cells having markedly sinuous walls. Microhairs present; panicoid-type. Stomata common (obscured by papillae). Subsidiaries dome-shaped, or triangular (?-outlines obscure). Intercostal short-cells common; in cork/silica-cell pairs. Costal short-cells predominantly paired. Costal silica bodies saddle shaped (rather variable); not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; with arm cells; with fusoids. Leaf blade adaxially flat. Midrib conspicuous; having complex vascularization. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): cf. Bambusoideae (as a synonym?); Bambusodae; Bambuseae; Bambusinae. 1 species.

Distribution, phytogeography, ecology. Tropical East Africa.

Forest.

References, etc. Leaf anatomical: Metcalfe 1960.

Special comments. Fruit data wanting.


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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: 13th November 2017. delta-intkey.com/grass’.

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