Vietnamosasa

HABIT Perennial. Rhizomes elongated; leptomorph. Culms 50–112.5–150 cm long; woody. Culm-internodes terete. Lateral branches dendroid. Branch complement many (2/2). Culm-sheaths auriculate (1/1). Culm-sheath blade triangular (1/1). Ligule an eciliate membrane. Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades persistent (2), or deciduous at the ligule (1); linear (1), or lanceolate; herbaceous (2), or coriaceous (1); stiff (2), or firm (1). Leaf-blade midrib conspicuous (1/1). Leaf-blade venation with distinct cross veins.

INFLORESCENCE Synflorescence on the same culm as leaves (1), or on a separate leafless culm (2). Inflorescence a panicle; subtended by an unspecialized leaf-sheath (2), or a spatheole (1); exserted (2), or embraced at base by subtending leaf (1).

Panicle open.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 5 fertile florets (1), or 6 fertile florets (2), or 7 fertile florets, or 8–9 fertile florets (2); with diminished florets at the apex. Spikelets linear, or oblong; laterally compressed; 20–33.33–40 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes definite; glabrous (2), or pubescent (1).

GLUMES Glumes two (2), or several (1); persistent; shorter than spikelet. Lower glume ovate; chartaceous; without keels. Lower glume surface without pits. Lower glume apex acute. Upper glume ovate; chartaceous; without keels. Upper glume apex acute.

FLORETS Fertile lemma ovate; chartaceous; without keel; wingless; 11–15 -veined (1/2), or 17–23 -veined (1/2). Lemma surface unwrinkled; without grooves. Lemma apex obtuse (1/1). Palea 7 -veined (1/1). Palea keels ciliate. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 3; ciliate. Anthers 6. Stigmas 3.

FRUIT Caryopsis with adherent pericarp; apex unappendaged.

DISTRIBUTION Tropical Asia.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.