The grass genera of the world
Including Brizopyrum Link
Habit, vegetative morphology. Annual. Culms herbaceous. Culm internodes hollow. Leaves non-auriculate. Sheath margins free. Leaf blades linear; narrow; flat, or rolled (convolute when dry), or acicular; without cross venation. Ligule an unfringed membrane.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; without hidden cleistogenes.
Inflorescence. Inflorescence a single raceme, or paniculate (one-sided, with few, stiff branches); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate (the pedicels stout).
Female-fertile spikelets. Spikelets 4–22 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairy (with capitate hairs); the rachilla extension with incomplete florets.
Glumes two; very unequal to more or less equal (the upper longer); (the longer) shorter than the adjacent lemmas, or long relative to the adjacent lemmas; dorsiventral to the rachis; hairless; awnless; carinate; similar (leathery). Lower glume 3 nerved. Upper glume 3–5 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets.
Female-fertile florets 3–20. Lemmas similar in texture to the glumes; not becoming indurated; entire, or incised; when entire pointed, or blunt; awnless; hairy (below, with capitate hairs); carinate; 5(–7) nerved (the intermediates sometimes faint). Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 0.8–1.4 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit small (1.8–2.0 mm long); not grooved; compressed dorsiventrally. Hilum short. Embryo small. Endosperm hard; with lipid. Embryo with an epiblast.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (the costal zones confined to a narrow median and a broader one at each margin of the blade). Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals narrower and rectangular, with tessellated walls); differing markedly in wall thickness costally and intercostally (the costals thicker walled). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare (very few seen, confined to regions bordering the midrib); 37–51 microns long. Subsidiaries low dome-shaped, or parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells predominantly paired (and solitary). Costal silica bodies poorly developed (in the material seen); tall-and-narrow (mostly, poorly developed and ill-defined).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms probably present in discrete, regular adaxial groups (at the bases of the furrows - unclear in the material seen); in simple fans. All the vascular bundles accompanied by sclerenchyma (but the sclerenchyma very scanty). Combined sclerenchyma girders absent (small, inconspicuous adaxial strands only). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Parapholiinae. 5 species.
Distribution, phytogeography, ecology. Mediterranean, Europe.
Commonly adventive. Xerophytic; species of open habitats. In sandy places.
References, etc. Morphological/taxonomic: Stace 1981, 1985; Brullo and Pavone 1985. Leaf anatomical: this project.
Special comments. No attempt here to account for Flora Europaea re-alignment (1980), involving Catapodium and Scleropoa.
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’.