The grass genera of the world
Habit, vegetative morphology. Perennial; caespitose. Culms 60–130 cm high; herbaceous. Leaf blades broad, or narrow; 5–25 mm wide; flat, or rolled (convolute or involute); pseudopetiolate (the pseudopetiole stiff); without cross venation. Ligule a fringe of hairs.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open, or contracted; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 2.5–4 mm long; compressed laterally; disarticulating above the glumes. Rachilla very shortly prolonged beyond the uppermost female-fertile floret, or terminated by a female-fertile floret; hairy; the rachilla extension (when present) naked.
Glumes two; very unequal (G2 longer), or more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; awnless; carinate; similar (spreading, ovate). Lower glume much shorter than half length of lowest lemma, or longer than half length of lowest lemma; 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only.
Female-fertile florets 2 (similar). Lemmas similar in texture to the glumes to decidedly firmer than the glumes; not becoming indurated (leathery); awnless (acuminate in Z. elegans); hairy (below the middle); 5–7 nerved. Palea present; awnless, without apical setae, or with apical setae; 2-keeled. Palea keels hairy (long-ciliate). Lodicules present; 2; free; membranous. Stamens 3.
Fruit, embryo and seedling. Endosperm containing compound starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls (and pitted; but the sinuations very fine; by contrast with the coarse sinuations of the costals). Microhairs present; panicoid-type (large, the apical cell as long as the basal cell). Stomata common. Subsidiaries dome-shaped. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; not paired (solitary (square-ish)); not silicified. Costal zones with short-cells. Costal short-cells conspicuously in long rows (though the short-cells sometimes rather long). Costal silica bodies oryzoid (very regular, cf. Pheidochloa); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade; without arm cells (but the cell walls frequently very sinuous). Leaf blade with distinct, prominent adaxial ribs; with the ribs very irregular in sizes (large, flat-topped and a few small round-topped). Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (large groups, regularly disposed between the ribs); 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 (all bundles). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Arundinoideae; Danthonieae. Soreng et al. (2015): Arundinoideae; Molinieae. 4 species.
Distribution, phytogeography, ecology. India, Ceylon, Burma.
Species of open habitats. Upland grassland.
References, etc. Leaf anatomical: studied by us - Z. elegans Trin.
Special comments. Fruit data wanting.
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’.