| # The grass genera of the world |

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

### Davidsea Soderstrom & Ellis

~ Teinostachyum (T. attenuatum (Thwaites) Munro)

Habit, vegetative morphology. Perennial. The flowering culms leafy. Culms 400–900 cm high; woody and persistent; to 1.5–2.5 cm in diameter; cylindrical; branched above. Buds from which the primary culm branches arise 1. Primary branches 4–10; clumped. The branching dendroid. Culm leaf sheaths present; deciduous; leaving a persisten girdle. Culm leaves with conspicuous blades. Culm leaf blades linear, or lanceolate. 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. Ligule truncate; 0.2–1 mm long. Contra-ligule present (in the form of a hard, glabrous rim).

Reproductive organization. Plants bisexual, all 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 unconventional; about 20 mm long; lanceolate; 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. Spikelets without proximal incomplete florets.

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); not convolute; 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 apically glabrous; without a conspicuous apical appendage. Styles fused (below). Stigmas 3 (shortly plumose).

Fruit, embryo and seedling. Fruit unknown.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (numerous, costally and intercostally). Intercostal papillae over-arching the stomata; several per cell (tall, variable in size and irregular in shape, thick-walled). Long-cells of similar wall thickness costally and intercostally (thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; clearly two-celled, or uniseriate (occasionally three-celled); panicoid-type (some with 2 basal cells); (57–)63–66(–69) microns long; (5.1–)6–6.6(–7.8) microns wide at the septum. Microhair total length/width at septum 8.8–12.9. Microhair apical cells (27–)28.5–30(–33) microns long. Microhair apical cell/total length ratio 0.43–0.53. Stomata common (in bands alongside the veins); 24–27 microns long. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies tall-and-narrow, or crescentic, or saddle shaped (the saddles mostly imperfect). Numerous, bulbous-based, tiny-pointed ‘prickles’ present. Costal short-cells predominantly paired (plus a few short rows). Costal silica bodies saddle shaped (abundant), or tall-and-narrow (a few), or oryzoid (a few); not sharp-pointed.

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 adaxially flat (except beside midrib). Midrib conspicuous (large); 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’ (all bundles). Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Melocanninae. 1 species (D. attenuata).

Distribution, phytogeography, ecology. Sri Lanka.

References, etc. Morphological/taxonomic: Soderstrom and Ellis 1988. Leaf anatomical: studied by us.

Special comments. Fruit data wanting.

Illustrations. • Davidsea attenuata, vegetative: Soderstrom et al., Smithsonian Contr. Bot. 72 (1988). • Davidsea attenuata, detailed morphology: Soderstrom et al., Smithsonian Contr. Bot. 72 (1988). • Davidsea attenuata, leaf anatomt: Soderstrom et al., Smithsonian Contr. Bot. 72 (1988). • D. attenuata (with Schizostachyum spp., all as Teinostachyum): Camus, 1913.. • Abbreviations for Camus (1913) figures. • Davidsea attenuata, abaxial epidermis of leaf blade: this project.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.

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: 15th June 2025. delta-intkey.com’.

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