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The grass genera of the world

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

Lepturidium Hitchc. and Ekman

~ Brachyachne

Type species: L. insulare Titchc. & Ekman.

Habit, vegetative morphology. Wiry perennial; caespitose, or decumbent. The flowering culms leafy. Culms 10–30 cm high; herbaceous; unbranched above. Leaves not basally aggregated; conspicuously distichous; non-auriculate. Sheaths overlapping, pilose or villous above and around the base of the blade. Leaf blades linear-lanceolate; narrow; 1–2 mm wide (and 1–2 cm long); flat, or rolled (becoming involute, the tips hard, obtuse, boat-shaped); without abaxial multicellular glands; without cross venation; persistent. Ligule a fringe of hairs.

Reproductive organization. Plants dioecious (according to the original description - no pistils found in the specimens examined; but Clayton et al. descriptions do not mention this, while offering no information on female components); according to Hitchcock and Ekman, without hermaphrodite florets. The spikelets hermaphrodite, or female-only, or male-only (?). Plants presumably outbreeding.

Inflorescence. Inflorescence a single raceme (with appressed spikelets). Inflorescence with axes ending in spikelets. Rachides triquetrous. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund; biseriate; subsessile; not imbricate.

Female-sterile spikelets. The exclusively male spikelets 3 mm long, with two equal, awnless, 1-nerved glumes. One proximal male floret with three stamens, its lemma 3 nerved, mucronate between two very short teeth. Second floret more or less reduced, sometimes paleate but sterile. Rachilla of male spikelets prolonged beyond the uppermost male floret. The male spikelets with glumes (two); without proximal incomplete florets; 2 floreted (the lower fertile). The lemmas mucronate. Male florets 1; 3 staminate.

Female-fertile spikelets. Spikelets probably morphologically ‘conventional’ (? - male only, on specimens described).

Spikelets probably without proximal incomplete florets.

Female-fertile florets probably 1 (? - cf. Brachyachne).

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally (fairly thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls (the sinuosity fine to coarse, regular to irregular). Microhairs present; more or less spherical to elongated; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhair basal cells 15 microns long. Microhair total length/width at septum 2. Microhair apical cell/total length ratio 0.5. Stomata common. Subsidiaries non-papillate; triangular (mostly of the truncated type). Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells fairly common; in cork/silica-cell pairs; silicified. Intercostal silica bodies imperfectly developed; short dumb-bell shaped, like some of the costals. No macrohairs or prickles seen. Costal short-cells conspicuously in long rows. Costal silica bodies present and well developed; present in alternate cell files of the costal zones; ‘panicoid-type’ (large); dumb-bell shaped (often with a quite long isthmus).

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.

C4; XyMS+. PCR sheath outlines uneven to even (the lowermost, abaxial cell on each side often much enlarged). PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions absent. Mesophyll traversed by columns of colourless mesophyll cells (perhaps, in places?), or not traversed by colourless columns (?). Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (‘anchors’ with all the bundles, the abaxial girders interrupting the PCR sheaths, the adaxial girders not doing so). Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.

Special diagnostic feature. Inflorescence not as in Buchloë (q.v.).

Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae. 1 species (the rare L. insulare).

Distribution, phytogeography, ecology. Cuba.

Species of open habitats; halophytic (on salt flats).

References, etc. Morphological/taxonomic: Hitchcock and Ekman (1936), in ‘Manual of the Grasses of the West Indies’, USDA Miscellaneous Publ. 243, Washington. Leaf anatomical: studied by us - L. insulare Hitchc. & Ekman.

Special comments. Fruit data wanting. Illustrations. • L. insulare: Hitchcock (1936)

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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.’.