The grass genera of the world
Habit, vegetative morphology. Perennial. The flowering culms leafy. Culms woody and persistent (the lowermost internode usually disproportionately elongate, usually with the others condensed so that the leaves cluster atop the canes); not scandent; sparsely to amply branched above, or unbranched above. The branching simple. Culm leaf sheaths present, or absent (mostly). Culm internodes solid, or hollow. Unicaespitose. Rhizomes pachymorph. Plants unarmed. Leaves not basally aggregated; with auricular setae. Leaf blades leathery; broad; pseudopetiolate, or not pseudopetiolate; cross veined, or without cross venation; disarticulating from the sheaths; rolled in bud. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence many spikeleted, or few spikeleted (rarely); of spicate main branches, or a single raceme, or paniculate (terminating leafy or leafless branches, sometimes terminating the culms, generally long and narrow, the branching racemose to paniculate); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes racemes, or spikelike, or paniculate; persistent. Spikelets usually secund; sessile to pedicellate.
Female-fertile spikelets. Spikelets 3–4 mm long; oblong (usually), or elliptic, or ovate, or linear (in M. distantiflorus); disarticulating above the glumes; not disarticulating between the florets, or disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes two; shorter than the adjacent lemmas; not pointed; awnless. Spikelets with incomplete florets. The incomplete florets both distal and proximal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets with proximal incomplete florets. The proximal incomplete florets 1. The proximal lemmas awnless; similar in texture to the female-fertile lemmas.
Female-fertile florets 2–5. Lemmas not becoming indurated; entire; pointed, or blunt; awnless. Palea present; relatively long; not convolute; entire; awnless, without apical setae; 2-keeled (and sulcate). Lodicules present; 3; membranous; glabrous; not toothed; heavily vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary without a conspicuous apical appendage. Styles fused (short). Stigmas 2.
Fruit, embryo and seedling. Hilum long-linear.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; intercostal, or costal and intercostal (in places). Intercostal papillae over-arching the stomata (in rings); several per cell. Long-cells markedly different in shape costally and intercostally (the costals regular, elongated-rectangular, the intercostals less regular and generally relatively short); of similar wall thickness costally and intercostally. Intercostal zones with typical long-cells (though these largely interstomatal and relatively short, the stomata being abundant in most places). Mid-intercostal long-cells having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; panicoid-type (large). Stomata common. Subsidiaries seemingly non-papillate; seemingly mostly triangular. Guard-cells with outlines obscured by the papillae. Intercostal short-cells absent or very rare. Costal short-cells predominantly paired. Costal silica bodies rounded (mostly), or saddle shaped (a few clear examples); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with adaxial palisade; with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat. Midrib not readily distinguishable. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans (these large, the median cell deep-penetrating). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures (a few bundles with Is, the adaxial arms slender). Sclerenchyma not all bundle-associated. The extra sclerenchyma in abaxial groups and in adaxial groups; abaxial-hypodermal, the groups isolated and adaxial-hypodermal, contiguous with the bulliforms (there being fibres flanking the bulliform groups, and an abaxial fibre group opposite each bulliform group).
Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Arthrostylidiinae. 20 species.
Distribution, phytogeography, ecology. Venezuela.
Helophytic, or mesophytic. Sandstone tablelands, over 1000 m.
References, etc. Leaf anatomical: this project.
Illustrations. • M. virgatus: Swallen (1951), Fieldiana Bot. 28. • M. paludicolus, abaxial epidermis of leaf blade: this project. • M. paludicolus, leaf blade TS: 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’.