Snowdenia C.E. Hubb.
Including Beckera Fresen.
Habit, vegetative morphology. Annual, or perennial; stoloniferous, or decumbent. Culms 15–180 cm high; herbaceous. Culm nodes glabrous. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; without cross venation; persistent; membranous; 1 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence of spicate main branches (slender spiciform racemes), or a single raceme; digitate, or non-digitate (when of a single raceme); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund; pedicellate.
Female-fertile spikelets. Spikelets 2–4 mm long; adaxial; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes present; two; minute; more or less equal; shorter than the adjacent lemmas; dorsiventral to the rachis; not pointed; awnless; similar (reduced to small, rotund scales). Lower glume 0 nerved. Upper glume 0 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; sterile. The proximal lemmas usually awned; decidedly exceeding the female-fertile lemmas (equalling the spikelet).
Female-fertile florets 1. Lemmas not becoming indurated (membranous); entire; pointed; awnless, or mucronate, or awned. Awns when present, 1; apical; non-geniculate; much shorter than the body of the lemma. Lemmas hairless; non-carinate; having the margins lying flat on the palea; 3–5 nerved. Palea present; conspicuous but relatively short (less than half the floret length). Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary glabrous. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small; compressed dorsiventrally. Hilum short. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Mid-intercostal long-cells having markedly sinuous walls. Microhairs present; panicoid-type; 28–45 microns long. Microhair apical cells 16–27 microns long. Microhair apical cell/total length ratio 0.55. Stomata common. Subsidiaries high dome-shaped and triangular. Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies infrequent, ‘panicoid-type’; nodular; not sharp-pointed.
Transverse section of leaf blade, physiology. C4; XyMS–. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib conspicuous; having a conventional arc of bundles; with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups (the epidermis partly, irregularly bulliform). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.
Culm anatomy. Culm internode bundles scattered.
Taxonomy. Panicoideae; Panicodae; Paniceae (Arthropogoneae).
Distribution, ecology, phytogeography. 4 species; tropical East Africa. Forest margins.
Paleotropical. African. Sudano-Angolan. Sahelo-Sudanian, Somalo-Ethiopian, and South Tropical African.
Rusts and smuts. Rusts — Puccinia.
Economic importance. Important native pasture species: S. polystachya.
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).