The grass genera of the world
Habit, vegetative morphology. Perennial; densely caespitose. Culms 8–50 cm high; herbaceous. Leaves non-auriculate. Sheath margins free. Leaf blades linear; narrow; 1 mm wide; setaceous (glaucous); rolled; without cross venation; persistent. Ligule present; an unfringed membrane; not truncate; 2–7 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open to contracted. Rachides scabrous. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 3–7.5 mm long; compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairy; the rachilla extension with incomplete florets. Hairy callus present (with a crown of hairs 0.3–0.6 mm long).
Glumes two; very unequal to more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; pointed (acute); awnless; carinate; similar. Lower glume 3 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.
Female-fertile florets 2–8. Lemmas similar in texture to the glumes; not becoming indurated; entire, or incised; when entire pointed, or blunt; mucronate, or awned (very shortly so). Awns 1; median; from a sinus (or the mucro from a notch), or apical; non-geniculate; to 1.5 mm long, much shorter than the body of the lemma; entered by one vein. Lemmas hairless (shortly hairy at base, scabrid on keels, not lanate); carinate; without a germination flap; 5 nerved. Palea present; relatively long; 2-nerved; 2-keeled (hairy between the keels). Lodicules present; 2; free; membranous; ciliate, or glabrous; more or less toothed (irregularly dentate or with 1–2 slender laeral lobes); not or scarcely vascularized. Stamens 3. Anthers 1.4–2.5 mm long. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea; small (c. 1.8–2.5 mm long); more or less longitudinally grooved; compressed dorsiventrally, or not noticeably compressed to trigonous. Hilum short. Embryo small. Endosperm hard; with lipid. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally (thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls (the sinuosity associated with conspicuous pitting). Microhairs absent. Stomata absent or very rare (none seen). Intercostal short-cells common; commonly in cork/silica-cell pairs; silicified. Intercostal silica bodies rounded to crescentic. With scattered costal and intercostal prickles. Costal short-cells predominantly paired. Costal silica bodies present and well developed; rounded and crescentic.
Transverse section of leaf blade, physiology. C3; XyMS+. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size (round topped, one per bundle). Midrib conspicuous to not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups, or not present in discrete, regular adaxial groups (inconspicuous, in the material seen); if present, in simple fans (of small cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders mostly absent (the material sectioned exhibiting only one combined girder, associated with the marginal bundle on one side of the blade, the others (including the midrib) with broad-footed abaxial girders and adaxial strands). Sclerenchyma all associated with vascular bundles, or not all bundle-associated (in one of the two specimens seen). The extra sclerenchyma when present, in a continuous abaxial layer.
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Chromosomes large.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Poinae. 1 species (B. variegata).
Distribution, phytogeography, ecology. Southern Europe, western Asia.
Helophytic; species of open habitats; glycophytic.
References, etc. Leaf anatomical: studied by us.
Illustrations. • B. polychroa: Fl. Iraq, 1968
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’.