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The grass genera of the world

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

Trilobachne Schenk ex Henrard

Habit, vegetative morphology. Annual. Culms 20–100 cm high (or more?); herbaceous. Culm nodes hairy. Plants unarmed. Leaves not basally aggregated. Leaf blades linear-lanceolate, or lanceolate; narrow; 50–75 mm wide (to 70 cm long); not pseudopetiolate.

Reproductive organization. Plants monoecious with all the fertile spikelets unisexual; without hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; female-only and male-only. The male and female-fertile spikelets in different inflorescences (at least, in different partial inflorescences). The spikelets overtly heteromorphic.

Inflorescence. Inflorescence of distinct male and female partial inflorescences mixed in fascicles in the upper leaf axils; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs (with a hierarchy of spathes and spatheoles). Spikelet-bearing axes ‘racemes’; clustered (panicled); with substantial rachides; disarticulating; disarticulating at the joints (swollen at base of fertile spikelets). ‘Articles’ non-linear; disarticulating transversely. Spikelets sessile and pedicellate, or subsessile and pedicellate; consistently in ‘long-and-short’ combinations (in both male and female inflorescences); in pedicellate/sessile combinations, or unequally pedicellate in each combination. Pedicels of the ‘pedicellate’ spikelets free of the rachis (to somewhat fused at their bases). The ‘shorter’ spikelets female-only (female inflorescence), or male-only (male inflorescence). The ‘longer’ spikelets sterile.

Female-sterile spikelets. Male spikelets each with 2 male florets, each with 2 fleshy, glabrous lodicules and 3 free stamens. Rachilla of male spikelets terminated by a male floret. The male spikelets without proximal incomplete florets; 2 floreted (both fertile). Male florets 2; 3 staminate.

Female-fertile spikelets. Spikelets 7–8 mm long; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; more or less equal; long relative to the adjacent lemmas; G1 hairy; awnless; non-carinate; very dissimilar (G1 crustaceous, cupular at the base, trilobed with the central lobe largest, the G2 ovate-acute, thinner). Lower glume not two-keeled. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; sterile. The proximal lemmas awnless; 13–15 nerved; decidedly exceeding the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); not becoming indurated; entire; pointed, or blunt; awnless; hairless; non-carinate; without a germination flap. Palea present (but small); conspicuous but relatively short (about 1/3 of the lemma length); entire to apically notched; awnless, without apical setae; not indurated (hyaline); nerveless; keel-less. Lodicules absent. Stamens 0. Ovary apically glabrous. Stigmas 2; red pigmented.

Fruit, embryo and seedling. Fruit slightly longitudinally grooved; compressed dorsiventrally. Hilum long-linear (elongated, in the sulcus).

Cytology. 2n = 20.

Classification. Watson & Dallwitz (1994): Panicoideae; Andropogonodae; Maydeae. Soreng et al. (2015): Panicoideae; Andropogonodae; Andropogoneae; Chionachninae. 1 species (T. cookei).

Distribution, phytogeography, ecology. India.

Forest margins.

References, etc. Morphological/taxonomic: Stapf 1894.

Special comments. Anatomical data wanting. Illustrations. • T. cookei, as Polytoca: Hook. Ic. Pl. 24 (1895)

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.’.