The grass genera of the world
The grass genera of the world | |
Melica: an ancient Italian name for a sorghum.
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; unbranched above; 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, 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 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.
Taxonomy. Pooideae; Poodae; Meliceae.
Distribution, ecology, phytogeography. About 80 species; North temperate, southern Africa and South America. Mesophytic to xerophytic; shade species and species of open habitats.
Holarctic, Paleotropical, Neotropical, Cape, and Antarctic. Boreal, Tethyan, and Madrean. African and Indomalesian. Euro-Siberian, Eastern Asian, Atlantic North American, and Rocky Mountains. Macaronesian, Mediterranean, and Irano-Turanian. Saharo-Sindian and Sudano-Angolan. Indian and Indo-Chinese. Caribbean, Pampas, and Andean. Patagonian. European and Siberian. Canadian-Appalachian, Southern Atlantic North American, and Central Grasslands. South Tropical African.
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. • General aspect (M. uniflora). • General aspect (M. racemosa). • Close-up of inflorescence detail (M. californica). Melica californica. Each spikelet with a modified rachilla extension bearing sterile florets forming a clubshaped tip. • Spikelets in close-up (M. californica). • Detaiul of modified rachilla tip (M. californica)
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. 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 specified attributes, summaries of attributes within groups of taxa, geographical distribution, classification, and species sampled for anatomy.
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: 11th February 2012. http://delta-intkey.com’.
