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The grass genera of the world

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

Pseudovossia A. Camus

~ Phacelurus, = Phacelurus (Vossia) cambogiensis

Habit, vegetative morphology. Culms herbaceous; unbranched above. Leaf blades without cross venation.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and male-only; overtly heteromorphic (the pedicelled spikelet laterally flattened); all in heterogamous combinations.

Inflorescence. Inflorescence digitate; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes ‘racemes’; solitary; with substantial rachides (the joints relatively long by contrast with Vossia); disarticulating; disarticulating at the joints. ‘Articles’ not appendaged; disarticulating transversely. Spikelets paired (the pairs relatively remote, by contrast with Vossia); sessile and pedicellate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations (the pedicels long and articulated in the middle). Pedicels of the ‘pedicellate’ spikelets free of the rachis. The ‘shorter’ spikelets hermaphrodite (and not embedded in the rachis). The ‘longer’ spikelets male-only.

Female-sterile spikelets. The pedicellate spikelets with a long callus, by contrast with Phacelurus. Male, laterally compressed, with a dorsally keeled G1.

Female-fertile spikelets. Spikelets compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; long relative to the adjacent lemmas; hairless; pointed; awnless; non-carinate; very dissimilar (the G1 leathery, 2-keeled, the G2 thinner, naviculate with a recurved apex). Lower glume two-keeled; flattened on the back; not pitted; relatively smooth. Spikelets with incomplete florets (hyaline). The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate; male. The proximal lemmas awnless (‘sub-aristate’); similar in texture to the female-fertile lemmas (hyaline).

Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); entire; pointed, or blunt; awnless; non-carinate; without a germination flap; faintly 3 nerved. Palea present; awnless, without apical setae; 2-nerved. Stamens 3. Ovary apically glabrous. Stigmas 2.

Classification. Watson & Dallwitz (1994): Panicoideae; Andropogonodae; Andropogoneae; Rottboelliinae. Soreng et al. (2015): Panicoideae (s a synonym); Andropogonodae; Andropogoneae. 1 species (P. cambogiensis).

Distribution, phytogeography, ecology. Indochina.

Special comments. Fruit data wanting. Anatomical data wanting. Illustrations. • P. cambogiensis: A. Camus, Bull. Bot. Soc. Fr. 22 (1922)

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: 11th December 2017.’.