The grass genera of the world
Type species: Type: S. scirpoidea (Steud.) C.E.Hubbard.
Habit, vegetative morphology. Juncus-like perennial (a switch plant, with reduced leaf blades and green culms); caespitose. Culms 30–60 cm high; herbaceous; unbranched above; culm bases rather swollen within the cataphylls. Culm internodes solid. Plants unarmed. Leaves mostly basal; non-auriculate. Leaf blades greatly reduced; narrow (tiny, reduced); without cross venation; disarticulating from the sheaths. Ligule a fringe of hairs. Contra-ligule present (of sparse hairs).
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; contracted; spicate; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate; consistently in long-and-short combinations; unequally pedicellate in each combination. Pedicels of the pedicellate spikelets free of the rachis. The shorter spikelets hermaphrodite. The longer spikelets hermaphrodite.
Female-fertile spikelets. Spikelets 4–5 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes two; more or less equal; shorter than the adjacent lemmas; lateral to the rachis (the spikelets tending to be flatwise against the rachis); hairless; pointed; awnless (but mucronate); carinate; similar (membranous). Lower glume 1–3 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.
Female-fertile florets 3–8. Lemmas similar in texture to the glumes (firmly membranous); not becoming indurated; entire, or incised; not deeply cleft; awnless, or mucronate (from a minute sinus); hairless; glabrous; somewhat carinate; without a germination flap; 5–9 nerved. Palea present; conspicuous but relatively short (about a third of the lemma length); apically notched (hairy at the tip); awnless, without apical setae; not indurated; 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit medium sized (about 5 mm long); black; slightly longitudinally grooved; sculptured (pitted). Hilum short. Pericarp thick and hard (black, with minute pits). Embryo small; not waisted. Endosperm hard; containing compound starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; about 45 microns long; 7.5 microns wide at the septum. Microhair total length/width at septum about 6. Microhair apical cells about 22.5 microns long. Microhair apical cell/total length ratio 0.5. Stomata common; 27–35 microns long. Subsidiaries medium dome-shaped. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.
Special diagnostic feature. Rush-like, with reduced leaf blades.
Classification. Watson & Dallwitz (1994): Arundinoideae; Spartochloeae. Soreng et al. (2015): Panicoideae; Cyperochloeae. 1 species (S. scirpoidea).
Distribution, phytogeography, ecology. Australia.
Xerophytic; species of open habitats. Arid places.
References, etc. Morphological/taxonomic: Hubbard 1952; Macfarlane and Watson 1980. Leaf anatomical: studied by us.
Illustrations. • S. scirpodia: Gardner, 1952
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.
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: 11th December 2017. delta-intkey.com/grass’.