| # The grass genera of the world |

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

### Vietnamocalamus T.Q. Nguyen

Type species: V. catbaensis.

Habit, vegetative morphology. Perennial; rhizomatous. The flowering culms leafy. Culms erect, 150–250 cm high; woody and persistent; to 5–10 cm in diameter; cylindrical; branched above. Primary branches 1. The branching suffrutescent. Culm leaf sheaths present. Rhizomes leptomorph. Leaves auriculate (these falcate); with auricular setae. Leaf blades lanceolate; broad; 20–26 cm long, 30–45 mm wide; not pseudopetiolate. Ligule an unfringed membrane; truncate; 0.5 mm long. Contra-ligule absent.

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

Inflorescence. Inflorescence axillary, basally embraced by the subtending leaf, reduced to a single spikelet, or few spikeleted. Spikelets solitary; not secund; pedicellate.

Female-fertile spikelets. Spikelets fairly morphologically ‘conventional’; 15 mm long; linear; compressed laterally to not noticeably compressed (subterete); disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.

Glumes persistent, several (three); shorter than the spikelets; awnless; chartaceous, non-carinate; lanceolate, similar. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awnless.

Female-fertile florets 3–4. Lemmas lanceolate; chartaceous, similar in texture to the glumes; without grooves, smooth; not becoming indurated; entire; pointed; awnless; non-carinate; 7 nerved. Palea present; not convolute; chartaceous, textured like the lemma. Lodicules present; 3. Stamens 3. Anthers 3 mm long. Ovary without a conspicuous apical appendage. Stigmas 2.

Fruit, embryo and seedling. Pericarp fused.

Classification. Watson & Dallwitz (1994): genus not recognised. Soreng et al. (2015): Bambusoideae; Arundinarodae; Arundinarieae; Arundinariinae. 1 species (V. catbaensis).

Distribution, phytogeography, ecology. China and Indo-China.

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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