Grass Genera of the World

L. Watson and M. J. Dallwitz


Hypseochloa C.E. Hubb.

Habit, vegetative morphology. Slender annual. Culms 4–16 cm high; herbaceous. Leaves non-auriculate. Leaf blades narrow; flat, or rolled; without cross venation; persistent; an unfringed membrane; not truncate; 1–3 mm long.

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

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

Female-fertile spikelets. Spikelets 2–3 mm long; compressed laterally to not noticeably compressed; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension naked (minute). Hairy callus present. Callus short; blunt.

Glumes present; two; more or less equal; exceeding the spikelets; long relative to the adjacent lemmas (exceeding them); pointed (acuminate); awnless; carinate; similar (membranous). Lower glume 3 nerved, or 5 nerved. Upper glume 3 nerved, or 5 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas decidedly firmer than the glumes (thinly leathery); becoming indurated (at least by contrast with Agrostis); incised; 2 lobed (shortly bidentate); not deeply cleft; awned. Awns 1; median; dorsal; from near the top, or from well down the back; geniculate; much longer than the body of the lemma; entered by one vein. Lemmas hairless; glabrous, or scabrous; non-carinate; having the margins inrolled against the palea; without a germination flap; 5–7 nerved. Palea present; relatively long; tightly clasped by the lemma; minutely apically notched; awnless, without apical setae; not indurated (hyaline/membranous); 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Ovary glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small (1.2 mm long); not grooved; compressed dorsiventrally, or not noticeably compressed. Hilum short. Embryo small. Endosperm hard; with lipid; containing compound starch grains.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (costals shorter, bulbous); of similar wall thickness costally and intercostally (thin-walled). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common; 42–57 microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired (mostly solitary or paired). Costal silica bodies horizontally-elongated crenate/sinuous (many deeply crenate, some almost ‘nodular’, sometimes with pointed corners); sharp-pointed (many of the crenate/nodular silica-bodies have pointed ‘corners’).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma (in places); without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs to ‘nodular’ in section; with the ribs more or less constant in size (low, round-topped). Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in the furrows); in simple fans (these broad). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent (mostly strands only). Sclerenchyma all associated with vascular bundles.

Taxonomy. Pooideae; Poodae; Aveneae.

Distribution, ecology, phytogeography. 2 species; on mountains of Tropical West Africa. Mesophytic; species of open habitats; glycophytic. Mountain grassland.

Paleotropical. African. West African Rainforest.

References, etc. Leaf anatomical: this project.

Illustrations. • Abaxial epidermis of leaf blade. • Leaf blade transverse section


Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).

Index