The grass genera of the world
Including Beesha Munro, Irulia Bedd.
Habit, vegetative morphology. Perennial; reedy, or not reedy (shrubs). The flowering culms leafy. Culms 200–600 cm high; woody and persistent; to 5 cm in diameter; branched above. Buds from which the primary culm branches arise (where recorded) 1. The branching dendroid. Culm leaf sheaths present; deciduous, or persistent; commonly conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades linear, or lanceolate. Culm internodes hollow. Plants unarmed. Leaves not basally aggregated; auriculate (with pellucid dots); without auricular setae. Leaf blades broad; pseudopetiolate; disarticulating from the sheaths. Ligule an unfringed membrane; truncate; short. Contra-ligule present, or absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence indeterminate; with pseudospikelets; a false spike, with spikelets on contracted axes (the clusters stellate); spatheate, or espatheate. Spikelet-bearing axes capitate. Spikelets not secund.
Female-fertile spikelets. Spikelets unconventional; 18–50 mm long; lanceolate, or ovate; not noticeably compressed; falling with the glumes. Rachilla terminated by a female-fertile floret; hairless.
Glumes present; two; more or less equal; shorter than the adjacent lemmas; hairless; pointed; awnless (but shortly mucronate); non-carinate; similar. Lower glume much shorter than half length of lowest lemma; 40 nerved (or more, in material seen). Upper glume 40 nerved (or more, in material seen). Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1–3; sterile. The proximal lemmas awnless (but shortly mucronate); 40 nerved (or more, in material seen); exceeded by the female-fertile lemmas; similar in texture to the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas similar in texture to the glumes; not becoming indurated; entire; pointed; non-carinate; without a germination flap; 40 nerved (or more, in material seen). Palea present; relatively long; convolute around the flower, or not convolute; entire, or apically notched, or deeply bifid; awnless, without apical setae; not indurated; several nerved (9 or more in material seen); keel-less. Lodicules present; 1–5(–15); free; membranous; glabrous; toothed, or not toothed; heavily vascularized (sometimes up to 15 mm long). Stamens 6–120; monadelphous, or with free filaments to monadelphous. Anthers not penicillate; with the connective apically prolonged. Ovary apically glabrous; with a conspicuous apical appendage. The appendage long, stiff and tapering. Styles fused. Stigmas 3–6.
Fruit, embryo and seedling. Fruit free from both lemma and palea; large (2–5 cm long); ellipsoid, or subglobose, or pyriform; not noticeably compressed. Hilum not visible. Pericarp fleshy. Embryo not visible. Seed non-endospermic.
Seedling with a short mesocotyl; with a loose coleoptile. First seedling leaf without a lamina.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal papillae over-arching the stomata (and obscuring them); several per cell (often one row per long-cell). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 54–60 microns long; 7.5–9–10.5 microns wide at the septum. Microhair total length/width at septum 5.1–7.4. Microhair apical cells 25.5–30 microns long. Microhair apical cell/total length ratio 0.47–0.54. Stomata common (obscured papillae and sunken); 22.5–27 microns long. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Costal short-cells predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies saddle shaped, or crescentic (e.g. predominant in O. stridula); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade; with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat. Midrib conspicuous; having complex vascularization. The lamina distinctly asymmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans (the median cells deeply penetrating). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with most bundles); forming figures (with most bundles). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 12. 2n = 72. 6 ploid.
Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Melocanninae. 12 species.
Distribution, phytogeography, ecology. Madagascar, India, Ceylon.
References, etc. Leaf anatomical: Metcalfe 1960; studied by us - O. stridula Thw.
Illustrations. • O. stridula, O. rheedii (= scriptoria) and O. sivagiriana, with Cathariostachys capitata: Camus, 1913. • Abbreviations for Camus (1913) figures
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’.