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The grass genera of the world

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

Spheneria (C. Muell.) Pilg.

Habit, vegetative morphology. Small, delicate perennial; caespitose. Culms unbranched above. Culm nodes glabrous. Culm internodes solid. Leaves mostly basal; non-auriculate. Leaf blades narrow; setaceous (pilose); without cross venation; persistent. Ligule present; an unfringed membrane (jagged, small, with a conspicuous fringe adjoining it on the lamina); 0.25 mm long.

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

Inflorescence. Inflorescence of spicate main branches; with thin, delicate rachides. Primary inflorescence branches few. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund; biseriate; pedicellate (the pedicels appearing bipartite - inside glabrous, outside pilose).

Female-fertile spikelets. Spikelets unconventional (lacking an organ, assumed here to be the lower glume); 1 mm long; turbinate; abaxial; compressed dorsiventrally; falling with the glumes (the pedicel splitting lengthways). Rachilla terminated by a female-fertile floret. Hairy callus present (constituted by the length of ‘pedicel’ which comes away).

Glumes present; one per spikelet; the upper, only glume long relative to the adjacent lemmas; dorsiventral to the rachis; hairy (pilose with white hairs, and a subterminal transverse fringe); awnless; non-carinate. Upper glume faintly 5 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; sterile. The proximal lemmas membranous, pilose with white hairs and a subterminal fringe, like the glume, but apparently with a basal, pilose appendage fused to the outside of the pedicel - cf. Centrochloa); awnless; faintly 3 nerved; more or less equalling the female-fertile lemmas; less firm than the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas decidedly firmer than the glumes; becoming indurated (thinly); brown in fruit (shiny); entire; pointed, or blunt; awnless (but abruptly beaked, the beak hooked); hairless; non-carinate; having the margins lying flat on the palea; with a clear germination flap; faintly 3 nerved. Palea present; relatively long; 2-nerved (thinly indurated); 2-keeled. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small (about 1 mm long); compressed dorsiventrally. Hilum short. Embryo large. Endosperm hard.

Abaxial leaf blade epidermis. Costal/intercostal zonation lacking. Papillae absent. Mid-intercostal long-cells having markedly sinuous walls. Microhairs present; panicoid-type; (42–)45–51(–54) microns long; 5.4–5.7–6.9 microns wide at the septum. Microhair total length/width at septum 6.5–9.5. Microhair apical cells (22–)33–35(–38) microns long. Microhair apical cell/total length ratio 0.53–0.7. Stomata absent or very rare. Intercostal short-cells common; in cork/silica-cell pairs. Large macrohairs present, with complex cushion bases. Costal short-cells predominantly paired (all short-cells in cc/sc pairs). Costal silica bodies rounded (a few), or tall-and-narrow, or ‘panicoid-type’ (basically this type, commonly ‘reduced’); often one-sided cross shaped (often with sharp points); sharp-pointed (often has sharp points on the crosses).

Transverse section of leaf blade, physiology. C4; XyMS–. Leaf blade with distinct, prominent adaxial ribs; with the ribs very irregular in sizes. Midrib conspicuous (a larger rib); having a conventional arc of bundles (1 large and 2 small bundles). Bulliforms not present in discrete, regular adaxial groups. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma not all bundle-associated. The ‘extra’ sclerenchyma in a continuous abaxial layer.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paspaleae; Paspalinae. 1 species (S. kegelii).

Distribution, phytogeography, ecology. Tropical South America.

Savanna.

References, etc. Leaf anatomical: this project.

Illustrations. • S. kegelii, as S. setifolia: Hoehne (1839), Estrateigicas de Matto-Grosso ao Amazonas


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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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