The grass genera of the world
Habit, vegetative morphology. Annual; caespitose. Culms unbranched above. Culm nodes glabrous. Culm internodes solid. Leaves non-auriculate. Leaf blades pseudopetiolate (except those of upper culm leaves); without cross venation. Ligule a fringed membrane to a fringe of hairs.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant, or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile.
Inflorescence. Inflorescence a false spike, with spikelets on contracted axes (bearing complex reduced branch-systems, each with a few spikelets and lots of bristles, cf. Setaria); non-digitate. Inflorescence axes not ending in spikelets. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets with involucres of bristles. The bristles relatively slender, not spiny; persisting on the axis. Spikelets secund (dorsiventral racemes).
Female-fertile spikelets. Spikelets 3 mm long; not noticeably compressed; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two; relatively large; very unequal; shorter than the adjacent lemmas; hairless; pointed; awnless; non-carinate; similar. Lower glume 3 nerved. Upper glume 5 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; sterile. The proximal lemmas awnless; 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; rugose; becoming indurated; entire; pointed (and beaked); awnless; hairless; non-carinate; having the margins lying flat on the palea; 5 nerved. Palea present; relatively long; awnless, without apical setae; 2-nerved; 2-keeled, or keel-less. Lodicules present; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate. Ovary apically glabrous. Styles fused. Stigmas 2, or 3.
Fruit, embryo and seedling. Fruit small. Hilum short.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells having straight or only gently undulating walls. Microhairs present; panicoid-type (very narrow); (57–)60–72(–78) microns long; 30–40.5 microns wide at the septum. Microhair total length/width at septum 9.5–14.4. Microhair apical cells 5.4–6–6.3 microns long. Microhair apical cell/total length ratio 0.52–0.56. Stomata common; 30–33 microns long. Guard-cells overlapping to flush with the interstomatals. Prickles abundant, some with minute points which could be mistaken for papillae. Costal short-cells conspicuously in long rows. Costal silica bodies present and well developed (in addition to tiny birefringent crystals, which occur throughout the epidermis); panicoid-type, or acutely-angled (the panicoid forms often with acutely angled tips); sharp-pointed (the crosses and dumb-bells often with acutely-angled tips).
Transverse section of leaf blade, physiology. C4; XyMS (but some bundles XyMS+ - i.e. XyMS variable, cf. Spinifex). Mesophyll with radiate chlorenchyma. Leaf blade with the ribs more or less constant in size. Midrib conspicuous; having a conventional arc of bundles; with colourless mesophyll adaxially (the colourless tissue occurring across the blade). Bulliforms not present in discrete, regular adaxial groups. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae (as a synonym of Setaria); Panicodae; Paniceae; Cenchrinae. 2 species.
Distribution, phytogeography, ecology. Madagascar.
References, etc. Leaf anatomical: this project.
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: 13th November 2017. delta-intkey.com/grass’.