The grass genera of the world
Habit, vegetative morphology. Culms 70–175 cm high; herbaceous; unbranched above. Leaves not basally aggregated. Leaf blades linear to lanceolate (acuminate); broad, or narrow; 7–15 mm wide (30–50 cm long). Ligule truncate; 2–3 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; exposed-cleistogamous, or chasmogamous (?).
Inflorescence. Inflorescence paniculate; open (about 40 cm long, 15 cm wide); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate (the pedicels glabrous).
Female-fertile spikelets. Spikelets unconventional (through reduction of the glumes, cf. Oryza); 4–4.5 mm long; lanceolate; slightly compressed dorsiventrally; borne on and falling with the long, slender stipe of the floret, by contrast with Leersia. Rachilla terminated by a female-fertile floret.
Glumes absent (obsolete). Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas lanceolate, acute to awned; not becoming indurated (membranous or papery); entire; pointed; awnless, or awned. Awns when present, 1; median; apical (by attenuation of the lemma); non-geniculate; about 4.5 mm long. Lemmas hairy, or hairless; strongly 5–7 nerved. Palea present; relatively long; entire (acute); awnless, without apical setae; not indurated (membranous); 2-nerved, or several nerved (sometimes 3); one-keeled. Lodicules present; 2. Stamens 1. Anthers without an apically prolonged connective. Ovary apically glabrous. Stigmas 2.
Fruit, embryo and seedling. Fruit small (2 mm long). Hilum short. Pericarp very thin.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally to markedly different in shape costally and intercostally (the costals tending to be narrower); of similar wall thickness costally and intercostally (the walls of medium thickness). Mid-intercostal long-cells rectangular; having markedly sinuous walls (the sinuosity fairly regular). Microhairs present; elongated; clearly two-celled; panicoid-type. Stomata common. Subsidiaries non-papillate; fairly high dome-shaped to triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs. With a few intercostal prickles. Costal short-cells conspicuously in long rows. Costal silica bodies present and well developed; panicoid-type; dumb-bell shaped (mainly), or butterfly shaped (a few).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade nodular in section, or adaxially flat. Midrib conspicuous; having complex vascularization (a large bundle abaxially in the keel, and a small adaxial one superposed, the pair embedded in either colourless tissue or large-celled, thin-walled sclerenchyma). Bulliforms present in discrete, regular adaxial groups; in simple fans (of large cells, between adjoining vascular bundles). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming figures (Is). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 12. 2n = 24. 2 ploid.
Classification. Watson & Dallwitz (1994): Bambusoideae; Oryzodae; Oryzeae. Soreng et al. (2015): Oryzoideae; Oryzeae; Zizaniinae. 3 species.
Distribution, phytogeography, ecology. China, Riyukyu Is., Japan.
Helophytic; shade species. Forests.
References, etc. Morphological/taxonomic: Koidzum 1925. Leaf anatomical: studied by us - C. aquatica Koidz.
Special comments. Fruit data wanting. Illustrations. • C. aquatica (Fl. of China, 22)
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’.