| # The grass genera of the world |

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

### Vietnamosasa Nguyen

Name referring to Sasa (a bamboo genus, q.v.) and geography.

~ Arundinaria, Pseudosasa - including A. ciliata A. Camus and A. pusilla Chevalier and Camus

Habit, vegetative morphology. Perennial; rhizomatous. The flowering culms leafy. Culms 50–150 cm high (small bamboos); woody and persistent; to 0.3–1 cm in diameter; cylindrical; not scandent; branched above. Primary branches 11–20. The branching dendroid. Culm leaf sheaths present. Culm internodes solid, or hollow. Rhizomes leptomorph. Plants unarmed. Leaves not basally aggregated; auriculate; with auricular setae. Leaf blades linear-lanceolate; narrow; 2–8(–10) mm wide; broadly cordate (‘subauriculate’); pseudopetiolate; cross veined; disarticulating from the sheaths. Ligule present; membranous. Contra-ligule absent.

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

Inflorescence. Inflorescence determinate, or indeterminate (? -in V. pusilla, where the presence and number of glumes is variable, and the lower is sometimes gemmiparous); with pseudospikelets (?), or without pseudospikelets; spatheate, or espatheate. Spikelet-bearing axes ‘racemes’, or spikelike (flowering branches ‘simple’); clustered (in fascicles); persistent. Spikelets sessile to pedicellate.

Female-fertile spikelets. Spikelets morphologically ‘conventional’, or unconventional; 30–70 mm long; oblong, or linear; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret.

Glumes present, or absent (sometimes, in V. pusilla); when present, one per spikelet to two (V. pusilla), or two. Lower glume shorter than the lowest lemma. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets 6–12. Lemmas lanceolate; awnless; hairless; multinerved. Palea present; relatively long; not convolute; entire, or apically notched; awnless, without apical setae; several nerved; 2-keeled. Lodicules present; 3; free; membranous; ciliate; not toothed; heavily vascularized (below). Stamens 6. Anthers 3.5–7 mm long (the filaments short). Ovary without a conspicuous apical appendage. Styles basally fused. Stigmas 3; red pigmented.

Fruit, embryo and seedling. Fruit longitudinally grooved.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Bambusinae. 3 species (V. darlacensis, V. ciliata, V. pusilla).

Distribution, phytogeography, ecology. Southern Vietnam.

References, etc. Morphological/taxonomic: Nguyen, T.Q. (1990). New taxa of bamboos (Poaceae, Bambusoideae) from Vietnam. Botanicheskii Zhurnal 75, 221–225. See Chevalier and Camus 1921, A. Camus 1919 and E.G. & A. Camus 1923 for descriptions of included Arundinaria (Pseudosasa) species.

Special comments. Description inadequate. Fruit data wanting. Anatomical data wanting.

Illustrations. • Vietnamosasa pusilla, as Arundinaria: E.G. & A. Camus, Fl. Gén. de l'Indo-Chine (1923).

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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