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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.


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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: 13th November 2017. delta-intkey.com/grass’.

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