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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Ratzeburgia Kunth

Including Aikinia Wall.

Habit, vegetative morphology. Perennial; stoloniferous. Culms 30–50 cm high; herbaceous. Young shoots extravaginal. Leaves non-auriculate. Leaf blades narrow; 1–4 mm wide; without cross venation.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and male-only, or hermaphrodite and sterile; overtly heteromorphic.

Inflorescence. Inflorescence of one linear, flattened, rather fragile spicate ‘raceme’. Rachides flattened. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes spikelike; the spikelet-bearing axes with 6–10 spikelet-bearing ‘articles’ (‘8–10 noded’); solitary; with substantial rachides; disarticulating; disarticulating at the joints. ‘Articles’ non-linear; with a basal callus-knob; disarticulating transversely; somewhat hairy. Spikelets in triplets; secund (the rachis dorsiventral, the spikelets on one side); sessile and pedicellate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations (two opposite sessile spikelets appressed back to back, one pedicellate). Pedicels of the ‘pedicellate’ spikelets free of the rachis (but closely opposed). The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets sterile.

Female-sterile spikelets. The pedicellate spikelet sterile, vestigial.

Female-fertile spikelets. Spikelets 5.6 mm long; abaxial; compressed dorsiventrally; falling with the glumes (with the adjacent joint and pedicel). Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; more or less equal; long relative to the adjacent lemmas; free; dorsiventral to the rachis; awnless; very dissimilar (the G1 leathery or crustaceous, reticulate-ribbed, pitted, tuberculate and truncately winged at the tip, the G2 thinner and glabrous). Lower glume two-keeled (the keels apically broadly, truncately winged); lacunose with deep depressions (with 5–6 vertical rows of pits). Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas awnless; more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas less firm than the glumes (scarious); not becoming indurated; entire; pointed, or blunt; awnless; hairless; non-carinate; without a germination flap. Palea present; conspicuous but relatively short, or very reduced; awnless, without apical setae; not indurated (scarious). Lodicules present; free; glabrous. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Classification. Watson & Dallwitz (1994): Panicoideae; Andropogonodae; Andropogoneae; Rottboelliinae. Soreng et al. (2015): Panicoideae; Andropogonodae; Andropogoneae; Rottboelliinae. 1 species (R. pulcherrima).

Distribution, phytogeography, ecology. Burma.

Species of open habitats. Short grassland.

Special comments. Fruit data wanting. Anatomical data wanting. Illustrations. • R. pulcherrima: Kunth (1835). • R. pulcherrima: Wallich (1832), East Indian Plants III

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.’.