The grass genera of the world
Habit, vegetative morphology. Perennial; rhizomatous (usually, short to elongated). The flowering culms leafless. Culms 300–3000 cm high; woody and persistent; more or less; scandent, or not scandent; branched above. Buds from which the primary culm branches arise 1. Primary branches thinner than the stem, 1, or 2, or 3, or 4–10, or 11–20; when not solitary, horizontally aligned, or clumped (often with one dominating). The branching dendroid. Culm leaf sheaths present; deciduous, or persistent; not leaving a persistent girdle; conspicuously auriculate (rarely), or not conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades lanceolate, or ovate, or triangular (commonly). Rhizomes pachymorph. Plants usually conspicuously armed (with root thorns at the nodes). Leaves auriculate, or non-auriculate (when present, the auricles erect or falcate); without auricular setae. Leaf blades often with the midrib conspicuous, linear to linear-lanceolate, or lanceolate, or ovate, or elliptic; pseudopetiolate; cross veined to without cross venation; disarticulating from the sheaths (rarely), or persistent. Ligule an unfringed membrane, or a fringed membrane.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets hermaphrodite.
Inflorescence. Inflorescence indeterminate; with pseudospikelets; comprising bractiferous synflorescences, these usually untidily clustered at the nodes, but occasionally simple or paniculate; a complex of partial inflorescences and intervening foliar organs (with glumaceous or spathaceous subtending bracts). Spikelets variously appressed, ascending, spreading or deflexed, sessile.
Female-fertile spikelets. Spikelets unconventional; 3–170 mm long; oblong, or elliptic, or lanceolate, or linear; compressed laterally, or compressed laterally to not noticeably compressed; disarticulating above the glumes; disarticulating between the florets; with distinctly elongated rachilla internodes between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairy, or hairless; the rachilla extension with incomplete florets, or naked (very rarely).
Glumes usually persistent, two, or several; consistently shorter than the spikelets; shorter than the adjacent lemmas; hairy, or hairless; pointed, or not pointed; blunt, acute or rostrate, muticous or mucronate; non-carinate; membranous to coriaceous, the lower ovate, the upper ovate to lanceolate, very dissimilar to similar. Lower glume shorter than the lowest lemma; 7–17 nerved. Upper glume 7–19 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets, or both distal and proximal to the female-fertile florets. The distal incomplete florets merely underdeveloped. The proximal incomplete florets when present, 1, or 2; paleate, or epaleate; sterile. The proximal lemmas ovate, elliptic or lanceolate; variously acute, obtuse or mucronate, awnless; 10–27 nerved (the laterals obscure).
Female-fertile florets 1–17. Lemmas lanceolate, elliptic or ovate; similar in texture to the glumes (coriaceous); smooth; not becoming indurated; entire; pointed, or blunt; awnless, or mucronate, or awned (rarely). Awns when awned, 1; median; apical. Lemmas hairy, or hairless (glabrous to pilose); non-carinate. Palea present; relatively long; nearly always not convolute; several nerved (6–13); 2-keeled. Palea back glabrous, or scabrous, or hairy. Palea keels nearly always winged; glabrous, or scabrous, or hairy. Lodicules present; 3; membranous; ciliate, or glabrous. Stamens 3 (rarely), or 6. Ovary apically hairy (and sometimes hairy all over); with a conspicuous apical appendage, or without a conspicuous apical appendage. The appendage when present, broadly conical, fleshy.
Fruit, embryo and seedling. Fruit fusiform, oblong, ovoid or obovoid. Hilum when recorded, long-linear. Pericarp thin, or fleshy (rarely); loosely adherent, or fused. Embryo large to small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (small, rather obscure, variously shaped). Intercostal papillae not over-arching the stomata. Mid-intercostal long-cells having markedly sinuous walls. Stomata common. Subsidiaries low dome-shaped. Intercostal short-cells common (but more numerous and larger over the veins); nearly all in cork/silica-cell pairs; silicified. Intercostal silica bodies small, mostly somewhat crescentic. Prickles and macrohairs costally, and hooks intercostally. Costal zones with short-cells. Costal short-cells predominantly paired. Costal silica bodies present and well developed; saddle shaped.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; with arm cells (?); with fusoids (these small, scarce). Leaf blade with only slight adaxial ribs and furrows. Midrib conspicuous; having complex vascularization. Bulliforms present in discrete, regular adaxial groups; 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; forming figures.
Cytology. 2n = 46.
Classification. Watson & Dallwitz (1994): not described separately. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Guaduinae. About 30 species.
Distribution, phytogeography, ecology. The Americas.
Holarctic and Neotropical.
References, etc. Leaf anatomical: Metcalfe (1960) for G. paniculata only.
Illustrations. • G. angustifolia (vegetative), as Bambusa guadua: McClure, New World Bamboos (1973). • G. angustifolia (flowering), as Bambusa guadua and B. aculeata: McClure, New World Bamboos (1973). • G. paraguana, G. refracta, G. tagoara (as longifimbriata): Camus,1913. • Abbreviations for Camus (1913) figures. • G. tagoara (as glaziowii), G. virgata, G. trinii: Camus, 1913
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’.