Davidsea Soderstrom and Ellis
Sometimes referred to Teinostachyum (T. attenuatum (Thwaites) Munro)
Habit, vegetative morphology. Perennial. The flowering culms leafy. Culms 400–900 cm high; woody and persistent; to 2.5 cm in diameter; cylindrical; branched above. Primary branches/mid-culm node 3. Culm sheaths deciduous in their entirety (leaving a girdle). Culm internodes hollow. Unicaespitose. Rhizomes pachymorph. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; with auricular setae. Leaf blades lanceolate (acuminate); broad; 20–30 mm wide (10–20 cm long); flat; pseudopetiolate; without cross venation; disarticulating from the sheaths; rolled in bud; truncate; 0.2–1 mm long. Contra-ligule in the form of a hard, glabrous rim.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence indeterminate; with pseudospikelets (developing sympodially, by contrast with those of Pseudoxytenanthera etc.); terminating a leafy branch, consisting of a bracteate axis with capitate clusters of pseudospikelets along its length; spatheate. Spikelet-bearing axes capitate. Spikelets (i.e. the pseudospikelets) not secund; sessile.
Female-fertile spikelets. Spikelets about 20 mm long; falling with the glumes; not disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret.
Glumes one per spikelet (this being empty, and preceded by two gemmiferous bracts and a long internode); shorter than the spikelets; shorter than the adjacent lemmas; hairless; glabrous (with ciliate margins below); awnless (apiculate). Upper glume (i.e. the one glume) 11–15 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awnless.
Female-fertile florets 1. Lemmas convolute; similar in texture to the glumes (firm); not becoming indurated; entire; pointed; awnless (apiculate); hairless; glabrous; non-carinate; without a germination flap; 16 nerved (with transverse veinlets); with the nerves non-confluent. Palea present; relatively long (shorter than the lemma); apically notched; awnless, without apical setae; thinner than the lemma; not indurated; several nerved (5 - one between the keels and one down each side outside them); 2-keeled. Palea keels wingless; hairy. Lodicules present; 3; free; membranous; ciliate; not toothed; heavily vascularized. Stamens 6. Anthers about 2 mm long; not penicillate; with the connective apically prolonged (shortly apiculate). Ovary glabrous; with a conspicuous apical appendage. The appendage long, stiff and tapering. Styles fused (below). Stigmas 3 (shortly plumose).
Fruit, embryo and seedling. Fruit unknown.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae over-arching the stomata (absent from the median, astomatal region of the intercostal zone); several per cell (often lobed or of the coronate-pit type, cf. Poa helmsii). Long-cells markedly different in shape costally and intercostally (the costals narrower). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; panicoid-type. Stomata common. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies tall-and-narrow. Costal short-cells conspicuously in long rows. Costal silica bodies saddle shaped.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with adaxial palisade; with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade with distinct, prominent adaxial ribs (these narrow and flat-topped except to one side of the midrib, where they are much more prominent). 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’. Sclerenchyma all associated with vascular bundles.
Taxonomy. Bambusoideae; Bambusodae; Bambuseae.
Distribution, ecology, phytogeography. 1 species; Sri Lanka.
Paleotropical. Indomalesian. Indian.
References, etc. Morphological/taxonomic: Soderstrom and Ellis 1988. Leaf anatomical: Soderstrom and Ellis 1988.
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).