Pseudostachyum Munro
Sometimes referred to Schizostachyum
Habit, vegetative morphology. Perennial; rhizomatous. The flowering culms leafy. Culms 500–1600 cm high; woody and persistent; to 2.5 cm in diameter; scandent (above), or not scandent; branched above (near their tops). Culm sheaths truncate-triangular. Culm internodes hollow (the walls thin). Rhizomes culms arising singly from long creeping rhizome. Plants unarmed. Leaves not basally aggregated; with auricular setae (but these deciduous). Leaf blades lanceolate to elliptic (ending in a long, twisted, scabrous point); broad; 20–45 mm wide (8–30 cm long); not cordate, not sagittate (but asymmetric at the base); pseudopetiolate (the ‘petiole’ rather long, thick); cross veined; disarticulating from the sheaths; rolled in bud; ligule present; short.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence indeterminate; with pseudospikelets; paniculate (large, with drooping branches); non-digitate; spatheate (the panicle leafy, the units bracteate); a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelet-bearing axes ‘racemes’, or spikelike, or paniculate; persistent. Spikelets not secund; seemingly sessile and pedicellate.
Female-fertile spikelets. Spikelets 5 mm long; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes one per spikelet; shorter than the adjacent lemmas; hairless; mucronate; awnless. Upper glume 7 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped (the terminal rachilla bearing glumes or an imperfect floret).
Female-fertile florets 1. Lemmas similar in texture to the glumes (and similar in form); not becoming indurated; mucronate; usually finely ciliate above. Palea present; relatively long; convolute; not indurated (thin); 2-keeled (the keels ciliate). Lodicules present (large, persistent); 3–5; free; membranous; ciliate; not toothed (acute, rounded or truncate); heavily vascularized. Stamens 6. Anthers with the connective apically prolonged (apiculate). Ovary glabrous; with a conspicuous apical appendage. The appendage long, stiff and tapering. Styles fused (into one long, rigid style). Stigmas 2 (short).
Fruit, embryo and seedling. Fruit fruit supported by persistent glume, lemma, palea and lodicules. Pericarp thick and hard (crustaceous); free.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; intercostal. Intercostal papillae over-arching the stomata (and small - not seen elsewhere). Mid-intercostal long-cells having markedly sinuous walls (thin). Microhairs present; panicoid-type. Stomata common (obscured by papillae). Subsidiaries probably low dome-shaped. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies saddle shaped (narrower than the costals), or tall-and-narrow. Costal short-cells predominantly paired (plus a few short rows). Costal silica bodies saddle shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with arm cells; with fusoids (large). Leaf blade adaxially flat (except near midrib). 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 (with all the bundles); forming ‘figures’ (in many bundles).
Taxonomy. Bambusoideae; Bambusodae; Bambuseae.
Distribution, ecology, phytogeography. 1 species; Eastern Himalaya, Assam and Upper Burma. Shade species. Under large trees.
Paleotropical. Indomalesian. Indo-Chinese.
References, etc. Leaf anatomical: Metcalfe 1960.
Special comments. Fruit data wanting.
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).