The grass genera of the world
Habit, vegetative morphology. Perennial; densely caespitose. Culms 15–30 cm high; herbaceous; unbranched above. Plants unarmed. Leaves mostly basal; non-auriculate. Leaf blades narrow; 1–3 mm wide (and 3–5 cm long); without abaxial multicellular glands; without cross venation; persistent. Ligule hyaline; 1 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence a single raceme (with very short pedicels); the raceme curved, 1–2.4 cm long. Inflorescence axes not ending in spikelets (in that the rachis tip appears to be a naked point). Inflorescence not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets unaccompanied by bractiform involucres, not associated with setiform vestigial branches; secund; biseriate; shortly pedicellate.
Female-fertile spikelets. Spikelets 3.5 mm long; compressed laterally; disarticulating above the glumes (?). Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus present.
Glumes two; very unequal; shorter than the adjacent lemmas; free; awned (the G1 with 1 mm subule from a sinus, the G2 also incised, but with a 2.7 mm dorsal awn); non-carinate; very dissimilar (the G2 green, puberulent, its longer awn from low on the back). Lower glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets clearly specialised and modified in form (the second floret male or sterile, succeeded distally by several florets represented by a bunch of vestigial lemmas in the form of hyaline scales and long awns). Spikelets without proximal incomplete florets.
Female-fertile florets 1. Lemmas less firm than the glumes to similar in texture to the glumes (hyaline); not becoming indurated; incised; not deeply cleft; awned. Awns 1; median; from a sinus; non-geniculate; hairless; much shorter than the body of the lemma (very short, scarcely more than a mucro). Lemmas hairy; carinate (long-ciliate along the nerves); 3 nerved. Palea present; relatively long; apically notched; awnless, without apical setae (glabrous); not indurated (hyaline); 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary glabrous. Styles free to their bases. Stigmas 2.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; more or less spherical; ostensibly one-celled, or clearly two-celled; chloridoid-type (the basal cell often sunken). Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 12–15 microns long. Microhair basal cells 4–5 microns long. Microhairs 6–8.4 microns wide at the septum. Microhair total length/width at septum 1.8–2.3. Microhair apical cell/total length ratio 0.6–1. Stomata common; 25.5–31.5 microns long. Subsidiaries obscured by overlaps from the adjoining cells. Guard-cells overlapped by the interstomatals (in some files), or overlapping to flush with the interstomatals. Intercostal short-cells common (in some files); not paired (solitary); not silicified. Intercostal silica bodies absent. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; panicoid-type; mostly butterfly shaped and dumb-bell shaped.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions absent. Mesophyll traversed by columns of colourless mesophyll cells. Leaf blade nodular in section to adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (these linking with the traversing colourless cell columns). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming figures (all the bundles with Is or anchors). Sclerenchyma all associated with vascular bundles. The lamina margins without fibres.
Taxonomy. Chloridoideae; main chloridoid assemblage.
Distribution, ecology, phytogeography. 1 species; Angola and Zambia.
Paleotropical. African. Sudano-Angolan. South Tropical African.
References, etc. Leaf anatomical: this project.
Special comments. Fruit data wanting.
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using 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 specified attributes, summaries of attributes within groups of taxa, geographical distribution, classification, and species sampled for anatomy.
Cite this publication as: ‘Watson, L., 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: 18th December 2012. http://delta-intkey.com’.