Brachypodium P. Beauv.
From the Greek brachys (short) and podion (a little foot), in reference to subsessile spikelets.
Including Brevipodium A. & D. Löve, Trachynia Link, Tragus Panzer
Habit, vegetative morphology. Annual, or perennial; rhizomatous to caespitose. Culms 2200 cm high; herbaceous; unbranched above. Culm nodes hairy. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear; broad (rarely), or narrow; 312 mm wide; flat, or rolled (convolute); without cross venation; persistent; an unfringed membrane; truncate, or not truncate; 16 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets; inbreeding.
Inflorescence. Inflorescence few spikeleted; a single raceme, or paniculate (rarely); open. Rachides hollowed. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund (drooping to one side), or not secund; distichous; pedicellate.
Female-fertile spikelets. Spikelets 1340 mm long; compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes two; very unequal to more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; dorsiventral to the rachis; pointed; awned, or awnless; non-carinate; similar (lanceolate). Lower glume 57 nerved. Upper glume 79 nerved, or 11 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awned, or awnless. Spikelets without proximal incomplete florets.
Female-fertile florets 822. Lemmas ovate-lanceolate to acuminate; similar in texture to the glumes; not becoming indurated; entire; pointed; awned. Awns 1; median; apical; non-geniculate; much shorter than the body of the lemma to about as long as the body of the lemma; entered by several veins (35). Lemmas hairless; non-carinate; (5)79 nerved. Palea present; relatively long; entire (truncate); awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; ciliate; not toothed. Stamens 3. Anthers 0.44.5 mm long; not penicillate. Ovary hairy. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea (Trachynia), or free from both lemma and palea; medium sized; longitudinally grooved; compressed dorsiventrally; with hairs confined to a terminal tuft. Hilum long-linear. Embryo small; not waisted. Endosperm hard; without lipid; containing only simple starch grains. Embryo with an epiblast, or without 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; 79 veined.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls (rarely), or having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare, or common; in B. distachyon 2427 microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; not paired (mainly solitary); silicified (often, and with adjacent prickles), or not silicified. Intercostal silica bodies when present, rounded, or tall-and-narrow. Crown cells present, or absent. 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, rounded, and tall-and-narrow.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs, or nodular in section. Midrib conspicuous, or not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans (or the groups of fairly uniform cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures. Sclerenchyma all associated with vascular bundles.
Culm anatomy. Culm internode bundles in three or more rings.
Phytochemistry. Leaves without flavonoid sulphates (1 species).
Cytology. Chromosome base number, x = 5, 7, 9, and 10. 2n = 10, 14, 16, 18, 28, 30, 42, and 56. 2, 4, 6, and 8 ploid (and aneuploids). Chromosomes small.
Taxonomy. Pooideae; Triticodae; Brachypodieae.
Distribution, ecology, phytogeography. 16 species; temperate, and tropical mountains. Commonly adventive. Mesophytic; shade species and species of open habitats.
Holarctic, Paleotropical, Neotropical, and Cape. Boreal, Tethyan, and Madrean. African, Madagascan, and Indomalesian. Arctic and Subarctic, Euro-Siberian, Eastern Asian, and Atlantic North American. Macaronesian, Mediterranean, and Irano-Turanian. Saharo-Sindian, Sudano-Angolan, and West African Rainforest. Indo-Chinese, Malesian, and Papuan. Caribbean, Pampas, and Andean. European and Siberian. Central Grasslands. Sahelo-Sudanian, Somalo-Ethiopian, and South Tropical African.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia graminis, Puccinia coronata, Puccinia striiformis, Puccinia brachypodii-phoenicoidis, and Puccinia recondita. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae Tilletia. Ustilaginaceae Ustilago.
Economic importance. Significant weed species: B. distachyon (= Trachynia).
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. General aspect. Inflorescence, spikelet and floret
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).