Heteranthoecia Stapf
Habit, vegetative morphology. Annual; decumbent (mat-forming). Culms 20–30 cm high; herbaceous; branched above. Leaves not basally aggregated; non-auriculate. Leaf blades lanceolate; narrow; 2–5 mm wide; cross veined; a fringed membrane (very narrow), or a fringe of hairs.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets (the lower floret hermaphrodite, the upper female-only).
Inflorescence. Inflorescence of spicate main branches (a panicle of short, unilateral spikes). Inflorescence axes not ending in spikelets (the rachides ending in blunt naked tips). Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets secund; biseriate; contiguous.
Female-fertile spikelets. Spikelets 1.7–2.3 mm long; abaxial; compressed dorsiventrally; disarticulating above the glumes; disarticulating between the florets. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two; more or less equal; shorter than the adjacent lemmas; hairless; pointed; awnless; similar (firmly membranous, with hyaline margins). Lower glume 4–7 nerved. Upper glume 4–7 nerved. Spikelets with female-fertile florets only.
Female-fertile florets 2 (but the upper usually female-only, much shorter and blunter). Lemmas similar in texture to the glumes to decidedly firmer than the glumes (papery); becoming indurated (L1), or not becoming indurated (L2); entire; pointed (L1 acuminate), or blunt (L2 obtuse to subacute); awnless; hairy; non-carinate; having the margins inrolled against the palea; with a clear germination flap; 5 nerved. Palea present; relatively long; entire, or apically notched (slightly); awnless, without apical setae; not indurated; 2-nerved. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small; slightly compressed dorsiventrally. Hilum short. Embryo large. Endosperm containing only simple starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal zones without typical long-cells (these being cubical). Mid-intercostal long-cells having straight or only gently undulating walls. Microhairs present; panicoid-type; 15–22 microns long. Microhair apical cells 9–16 microns long. Microhair apical cell/total length ratio 0.68. Stomata common. Subsidiaries parallel-sided to triangular; including both triangular and parallel-sided forms on the same leaf. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies acutely-angled; sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma; Isachne-type. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in the furrows); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.
Taxonomy. Panicoideae; Panicodae; Isachneae.
Distribution, ecology, phytogeography. 1 species; tropical Africa. Helophytic (swamps and shallow water).
Paleotropical. African. Sudano-Angolan and West African Rainforest. Sahelo-Sudanian and Somalo-Ethiopian.
References, etc. Leaf anatomical: Metcalfe 1960.
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).