The grass genera of the world

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L. Watson and M. J. Dallwitz

Chusquea Kunth

Including Dendragrostis Jackson, Rettbergia Raddi

Excluding Swallenochloa

Habit, vegetative morphology. Perennial. The flowering culms leafy. Culms woody and persistent; scandent, or not scandent; branched above. Culm nodes glabrous. Primary branches/mid-culm node 3–12 (or more - unrestricted pleioclade). Culm sheaths persistent, or deciduous in their entirety. Culm internodes solid (rarely with an irregular passage formed by shrinkage of pith). Unicaespitose, or pluricaespitose. Rhizomes pachymorph, or leptomorph. Plants conspicuously armed, or unarmed. Young shoots extravaginal. Leaves not basally aggregated; non-auriculate; without auricular setae. Leaf blades broad, or narrow; pseudopetiolate; cross veined, or without cross venation; disarticulating from the sheaths. Ligule an unfringed membrane. Contra-ligule present.

Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence paniculate; open (rarely racemose or capitate); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes paniculate. Spikelets solitary; not secund; pedicellate.

Female-fertile spikelets. Spikelets 8–10 mm long (C. scandens); not noticeably compressed; disarticulating above the glumes. Rachilla terminated by a female-fertile floret; hairless. Hairy callus absent.

Glumes two; more or less equal; shorter than the adjacent lemmas; hairless; not pointed; awnless; non-carinate; similar. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1–3; sterile. The proximal lemmas awnless; 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; awnless, or mucronate (?); hairless; non-carinate; without a germination flap. Palea present; relatively long; apically notched to deeply bifid; awnless, without apical setae; not indurated; keel-less. Lodicules present; 3; free; membranous; ciliate; not toothed. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary glabrous; without a conspicuous apical appendage. Styles fused. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea; medium sized; slightly longitudinally grooved; not noticeably compressed. Hilum long-linear. Embryo small; not waisted.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal papillae several per cell. Long-cells similar in shape costally and intercostally, or markedly different in shape costally and intercostally; differing markedly in wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type. Stomata common. Subsidiaries papillate; dome-shaped, or triangular, or parallel-sided (the triangles often with blunted/truncated apices); including both triangular and parallel-sided forms on the same leaf, or not including both parallel-sided and triangular forms on the same leaf. Intercostal short-cells common. Costal short-cells conspicuously in long rows. Costal silica bodies saddle shaped, or ‘panicoid-type’; when panicoid type, cross shaped to dumb-bell shaped.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with arm cells; with fusoids. Leaf blade adaxially flat (adaxial ribs weakly developed). Midrib conspicuous; with one bundle only (rarely complex). Bulliforms present in discrete, regular adaxial groups; in simple fans (these wide or narrow). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 12. 2n = 40, 44, and 48. 4 ploid.

Taxonomy. Bambusoideae; Bambusodae; Bambuseae.

Distribution, ecology, phytogeography. More than 100 species; Mexico to Chile and Argentina. A very diverse genus with an altitudinal range from sea level to the lower limit of perpetual snow. Helophytic.

Neotropical and Antarctic. Caribbean, Venezuela and Surinam, Amazon, Central Brazilian, Pampas, Andean, and Fernandezian. Patagonian.

References, etc. Morphological/taxonomic: Soderstrom 1978; Soderstrom and Calderón 1978a, 1978b. Leaf anatomical: Metcalfe 1960; this project.

The descriptions are offered for casual browsing only. We strongly advise against extracting comparative information from them. This is much more easily achieved using 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, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).

Cite this publication as: ‘Watson, L., 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: 2nd April 2015.’.