Schoenefeldia Kunth
Habit, vegetative morphology. Annual, or perennial; caespitose. Culms 70–120 cm high; herbaceous. Leaves not basally aggregated; non-auriculate. Leaf blades linear; narrow; without abaxial multicellular glands; without cross venation; a fringed membrane (short).
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence of spicate main branches (usually 2–6 sessile, flexuous spikes); digitate. Primary inflorescence branches (1–)2–6. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund (on one side of the rachis); biseriate; sessile; imbricate.
Female-fertile spikelets. Spikelets strongly compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret. Hairy callus present.
Glumes two; very unequal; exceeding the spikelets; long relative to the adjacent lemmas (exceeding it); free; hairless; pointed; awned (G1, sometimes), or awnless; carinate; similar (persistent, narrow or setaceous, subhyaline, divergent). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets when present, distal to the female-fertile florets. The distal incomplete florets when present, 1; awned. Spikelets without proximal incomplete florets.
Female-fertile florets 1. Lemmas completely covering the palea; decidedly firmer than the glumes (often blackened at maturity); incised; 2 lobed; not deeply cleft (apically bifid); awned. Awns 1; median; from a sinus; non-geniculate, or geniculate; much longer than the body of the lemma (very long, flexuous, tangling one another). Lemmas hairy (with appressed hairs); non-carinate (rounded on the back); 3 nerved. Palea present; 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous. Stamens 2–3. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; ellipsoid; compressed laterally. Hilum short. Pericarp free. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; intercostal. Intercostal papillae not over-arching the stomata; consisting of one oblique swelling per cell. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; more or less spherical to elongated; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 21–24 microns long. Microhair basal cells 15–18 microns long. Microhairs 9–10–10.2 microns wide at the septum. Microhair total length/width at septum 2.2–2.7. Microhair apical cells 7.5–9.6–10.5 microns long. Microhair apical cell/total length ratio 0.36–0.46. Stomata common; 19.5–21 microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare; not paired. Intercostal silica bodies absent. Large prickles present costally. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; exclusively saddle shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheaths of the primary vascular bundles interrupted; interrupted both abaxially and adaxially. PCR sheath extensions absent. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming ‘figures’ (in all the bundles). Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.
Taxonomy. Chloridoideae; main chloridoid assemblage.
Distribution, ecology, phytogeography. 2 species; tropical Africa, Asia. Species of open habitats. Savanna, hardpans and seasonally flooded flats.
Paleotropical. African, Madagascan, and Indomalesian. Saharo-Sindian, Sudano-Angolan, and West African Rainforest. Indian. Sahelo-Sudanian, Somalo-Ethiopian, and South Tropical African.
References, etc. Leaf anatomical: this project.
Illustrations. • General aspect
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).
