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The grass genera of the world

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

Heterocarpha Stapf & C.E. Hubb.

~ Drake-Brockmania, Dinebra sensu lato

Habit, vegetative morphology. Perennial; stoloniferous and caespitose. Culms 15–63 cm high; herbaceous; unbranched above. Culm nodes glabrous. Plants unarmed. Leaves not basally aggregated; non-auriculate; without auricular setae. Sheath margins free. Leaf blades lanceolate; narrow; (2–)3–7(–9.5) mm wide (and 3–18 cm long); flat; without abaxial multicellular glands; without cross venation; persistent. Ligule present; a fringed membrane (a short rim, with a conspicuous fringe); 1–1.5 mm long. Contra-ligule absent.

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

Inflorescence. Inflorescence of spicate main branches (3.5–11 cm long, rather narrow, with short, dense racemes which are reflexed terminally). Primary inflorescence branches (5–)8–12. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. The racemes without spikelets towards the base. Spikelet-bearing axes persistent. Spikelets solitary; secund; biseriate (in two ranks on one side of rachis); subsessile; imbricate.

Female-fertile spikelets. Spikelets 6–10(–14) mm long; adaxial; markedly compressed laterally; disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairless (glabrous); the rachilla extension with incomplete florets. Hairy callus absent.

Glumes two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; dorsiventral to the rachis to lateral to the rachis; hairless (scabrid on the keels); pointed (acute); awnless; carinate; similar (ovate, membranous). Lower glume 1 nerved, or 2 nerved. Upper glume 5–8 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets (4–)5–10. Lemmas similar in texture to the glumes (membranous); smooth; not becoming indurated; entire to incised; not deeply cleft (blunt to slightly notched); mucronate (minutely, from the slight apical sinus); hairy (villous on margins and keels), or hairless (?); glabrous; carinate; without a germination flap; 5–7 nerved (with 2–4 very thin nerves between the three heavy ones). Palea present (bent); relatively long; apically notched; awnless, without apical setae; not indurated (membranous); 2-nerved; 2-keeled (hairy between the keels, deeply furrowed). Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers short; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2 (but sometimes with a vestigial third); red pigmented.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small (1 mm long); somewhat compressed laterally. Hilum short. Pericarp free (thin). Embryo large.

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

Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae. 1 species (H. haareri).

Distribution, phytogeography, ecology. Tropical East Africa.

Species of open habitats; halophytic. In maritime sands, in dry rather saline soils fringing Suaeda bush and in dry Acacia bush.

References, etc. Morphological/taxonomic: Stapf and Hubbard 1929.

Special comments. Referred to Drake-Brockmania by Phillips (1974), but in view of the morphological differences, anatomical data are badly needed for H. haareri and B. fragilis. Fruit data wanting. Anatomical data wanting. Illustrations. • H. haareri: Hutchinson, you hua zhi wu ke zhi shuang zi ye zhi wu (1955)

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.’.