The grass genera of the world
Including Beckeria Bernh., Bromelica (Thurber) Farw., Claudia Opiz, Dalucum Adans., Verinea Merino
Habit, vegetative morphology. Perennial; rhizomatous. Culms 10–150(–200) cm high; herbaceous; scandent (M. sarmentosa, via filiform, retrorsely scabrid leaf blade tips), or not scandent; sparsely to amply branched above, or unbranched above (commonly). The branching simple. Culms tuberous (often), or not tuberous. Culm internodes hollow. Leaves auriculate, or non-auriculate. Sheath margins joined. Leaf blades linear; broad to narrow; 1.3–15 mm wide; flat, or rolled (convolute); cross veined (rarely), or without cross venation; rolled in bud. Ligule an unfringed membrane to a fringed membrane, or a fringe of hairs (rarely); truncate, or not truncate; 0.1–4 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; exposed-cleistogamous, or chasmogamous.
Inflorescence. Inflorescence few spikeleted to many spikeleted; a single raceme, or paniculate; open, or contracted; with capillary branchlets, or without capillary branchlets; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets secund, or not secund; pedicellate.
Female-fertile spikelets. Spikelets 4–20 mm long; compressed laterally to not noticeably compressed; disarticulating above the glumes, or falling with the glumes (and sometimes disarticulating both above and below them); not disarticulating between the florets, or disarticulating between the florets (tardily or reluctantly); with conventional internode spacings, or with a distinctly elongated rachilla internode between the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus absent. Callus short (glabrous).
Glumes two; relatively large; very unequal to more or less equal; shorter than the spikelets, or about equalling the spikelets (usually?); shorter than the adjacent lemmas, or long relative to the adjacent lemmas (usually?); pointed, or not pointed; awnless; non-carinate; very dissimilar (the lower sometimes greatly enlarged), or similar (often coloured, papery, thin-tipped). Lower glume 1–7 nerved. Upper glume (3–)5–7 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped, or clearly specialised and modified in form (often, modified as a ball of successively enveloped lemmas or as a swollen rachilla extension). Spikelets without proximal incomplete florets.
Female-fertile florets 1–7. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (usually leathery, sometimes membranous); entire, or incised; when entire pointed, or blunt; awnless, or mucronate, or awned. Awns when present, 1; from a sinus, or apical; non-geniculate; straight; hairless; much shorter than the body of the lemma to about as long as the body of the lemma. Lemmas hairy, or hairless; non-carinate; without a germination flap; 5–9(–15) nerved. Palea present; relatively long, or conspicuous but relatively short, or very reduced; entire, or apically notched (bidentate); thinner than the lemma; 2-nerved; 2-keeled. Lodicules present; 2; joined; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers 0.6–3.5 mm long; not penicillate. Ovary apically glabrous; without a conspicuous apical appendage. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small; sometimes red; longitudinally grooved; compressed dorsiventrally, or not noticeably compressed. Hilum long-linear. Pericarp thin. Embryo small. Endosperm hard; without lipid; containing compound starch grains. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.
Seedling with a long mesocotyl; with a loose coleoptile, or with a tight coleoptile. First seedling leaf with a well-developed lamina. The lamina broad, or narrow; erect; 3–5 veined.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally, or markedly different in shape costally and intercostally; of similar wall thickness costally and intercostally, or differing markedly in wall thickness costally and intercostally. Mid-intercostal long-cells rectangular, or fusiform; having markedly sinuous walls, or having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare, or common. Subsidiaries parallel-sided. Intercostal short-cells common, or absent or very rare; not paired; silicified, or not silicified. Intercostal silica bodies when seen tall-and-narrow. Costal short-cells conspicuously in long rows, or predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth, or rounded; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs, or adaxially flat; with the ribs more or less constant in size. Midrib conspicuous, or not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (at the bases of the furrows); in simple fans (and sometimes also in groups of small, irregularly sized cells, cf. Ammophila). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures, or nowhere forming figures. Sclerenchyma all associated with vascular bundles.
Phytochemistry. Leaves without flavonoid sulphates (2 species).
Special diagnostic feature. Spikelets with the distal incomplete florets and/or the rachilla apex forming a terminal clavate appendage, or spikelets without a terminal clavate appendage.
Cytology. Chromosome base number, x = 9. 2n = 14 (rarely), or 18, or 36. 2 and 4 ploid. Chromosomes fairly large. Nucleoli disappearing before metaphase.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Meliceae. Soreng et al. (2015): Pooideae; Meliceae. About 80 species.
Distribution, phytogeography, ecology. North temperate, southern Africa and South America.
Mesophytic to xerophytic; shade species and species of open habitats.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia graminis, Puccinia coronata, Puccinia brachypodii, Puccinia poarum, and Puccinia schedonnardi. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae Urocystis. Ustilaginaceae Sphacelotheca and Ustilago.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • M. persica: Kunth (1835). • M. nutans, general aspect: Eng. Bot. (1872). • M. uniflora, general aspect: Eng. Bot. (1872). • General aspect (M. uniflora): J. Curtis, 1924. • General aspect (M. racemosa): Gibbs Russell et al., 1990. • M. californica, close-up of inflorescence detail: this project. Melica californica. Each spikelet with a modified rachilla extension bearing sterile florets forming a clubshaped tip. • Spikelets in close-up (M. californica). • M. californica, detail of modified rachilla tip: this project
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: 13th November 2017. delta-intkey.com/grass’.