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The grass genera of the world

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

Habrochloa C.E. Hubb.

Habit, vegetative morphology. Slender annual. Culms 5–50 cm high; herbaceous; unbranched above. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; 2–2.5 mm wide (and 1–8 cm long); flat; without cross venation. Ligule a fringe of hairs.

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

Inflorescence. Inflorescence paniculate; delicate, open; with capillary branchlets; non-digitate; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund.

Female-fertile spikelets. Spikelets 2–2.5 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus present (small). Callus short.

Glumes two; relatively large; more or less equal (the G2 slightly shorter); shorter than the spikelets to about equalling the spikelets; long relative to the adjacent lemmas (exceeding them); hairless; pointed (acute to acuminate); awnless; carinate; similar (linear-lanceolate, hyaline). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets 2–5. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (thinly membranous, translucent); not becoming indurated; incised; very shortly 2 lobed (the lobes themselves obtuse or minutely bidentate); not deeply cleft; awned. Awns 1; median; from a sinus; non-geniculate; gently recurving, or flexuous; hairless (scabrid); much longer than the body of the lemma (to about 7 mm long, very slender). Lemmas hairy; carinate; 3 nerved. Palea present; relatively long; entire to apically notched; awnless, without apical setae; not indurated (thinly membranous); 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers 0.1–0.3 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small (0.8–1 mm long); linear, or ellipsoid; trigonous. Hilum short. Embryo small (about 1/4 of the fruit length).

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular and fusiform; having markedly sinuous walls (but the sinuations gentle). Microhairs present; panicoid-type (the apical cells all missing in material seen); 30(–37.5) microns long; 5.4 microns wide at the septum. Microhair total length/width at septum 5.56–6.94. Microhair apical cells 16.5–21 microns long. Microhair apical cell/total length ratio 0.55–0.6. Stomata absent or very rare (though surprisingly so, in this relatively thin-walled epidermis); 21–22.5 microns long. Intercostal short-cells absent or very rare (none seen). Costal short-cells conspicuously in long rows (though some files have relatively long short-cells). Costal silica bodies ‘panicoid-type’; more or less exclusively dumb-bell shaped (large).

Transverse section of leaf blade, physiology. Almost certainly C3 (though the material seen poor); XyMS+. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms not present in discrete, regular adaxial groups. Combined sclerenchyma girders present; forming ‘figures’ (small anchors in the primaries only, the other bundles depauperate in sclerenchyma). Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Arundinoideae; Danthonieae. Soreng et al. (2015): Chloridoideae; Triraphideae. 1 species.

Distribution, phytogeography, ecology. East tropical Africa.

Shade species; glycophytic. On slopes.

References, etc. Morphological/taxonomic: Hubbard 1967a. Leaf anatomical: this project.


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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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