| # The grass genera of the world |

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

### Soejatmia K.M. Wong

~ Bambusa

Type species: S. ridleyi (Gamble) Wong.

Habit, vegetative morphology. Perennial; rhizomatous and caespitose. Culms 300–500 cm high; without nodal roots, woody and persistent; cylindrical; branched above. Buds from which the primary culm branches arise 1. Primary branches 3; clumped (in untidy tufts). The branching dendroid. Culm nodes hairy. Culm leaf sheaths present; conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades ovate. Culm internodes glabrous, 20–45 cm long, hollow. Rhizomes pachymorph. Leaves not basally aggregated; conspicuously auriculate (the auricles erect); with auricular setae. Leaf blades lanceolate; broad; 20–30 cm long, 25–50 mm wide; pseudopetiolate. Contra-ligule present.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets hermaphrodite.

Inflorescence. Inflorescence indeterminate; with pseudospikelets (subtended by glumaceous bracts smaller than the lemmas, with axillary buds at the bases of the spikelets, and prophylls below the lateral spikelets); comprising bractiferous nodal clusters; a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelets not secund; sessile.

Female-fertile spikelets. Spikelets unconventional; 40–50 mm long; lanceolate; compressed laterally; disarticulating above the glumes; disarticulating between the florets; with distinctly elongated rachilla internodes between the florets (5–7 mm long). Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets.

Glumes present; one per spikelet, or several (depending whose description you believe). Spikelets with incomplete florets. The incomplete florets both distal and proximal to the female-fertile florets (there being a ‘transitional glume’ subtending a sterile floret beneath the empty one). The distal incomplete florets 1–2; merely underdeveloped; awnless. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate; sterile. The proximal lemmas awnless.

Female-fertile florets 3–5. Lemmas lanceolate, 18–22 mm long; convolute; entire; pointed; mucronate; hairless; non-carinate. Palea present; relatively long; tightly clasped by the lemma; deeply bifid; with apical setae (the shortish pair of projections often hooked); several nerved (many - 12–16); 2-keeled. Palea keels hairy. Lodicules present; 8–9 mm long, 3; free; membranous; ciliate; not toothed. Stamens 6; with free filaments. Anthers with the connective apically prolonged. Ovary apically hairy; with a conspicuous apical appendage. The appendage broadly conical, fleshy. Styles fused. Stigmas 3.

Fruit, embryo and seedling. Pericarp thin.

Classification. Watson & Dallwitz (1994): genus not recognised. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Bambusinae. 1 species (S. ridleyi).

Distribution, phytogeography, ecology. Southern Malay Peninsula.

References, etc. Morphological/taxonomic: Clayton et al. (2016), Grassbase; K. M. Wong (1993): Four New Genera of Bamboos (Gramineae: Bambusoideae) from Malesia. Kew Bulletin 48, 517–532.

Special comments. Anatomical data wanting.

Illustrations. • Soejatmia ridleyi, as Bambusa: Gamble, Bambuseae of Br. ndia (1896).

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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