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50 6.01 BROMEAE • Bromus apc; anth 1–1.3 mm. Car equaling the pal, thin, weakly inrolled or flat. 2n = 14. Bromus squarrosus grows in overgrazed pastures, fields, waste places, and road verges. Native to central Russia and southern Europe, it can be found mainly in southern Canada and the northern half of the United States. 7. TRITICEAE Dumort. Mary E. Barkworth Pl ann or per; smt csp, smt rhz. Clm ann, not woody, usu erect, not brchg above the base; intnd hollow or solid. Shth usu open, those of the bas lvs smt closed; col without tufts of hair on the sides; aur usu present; lig memb or scarious, smt ciliolate, those of the up and lo cauline lvs usu similar; psdpet absent; bld linear to narrowly lanceolate, venation parallel, cross venation not evident, without arm or fusoid cells, surfaces without microhairs, not papillate, cross sections nonKranz . Infl usu spikes or spikelike rcm, with 1–5 sessile or subsessile spklt per nd, occ pan, smt with morphologically distinct strl and bisex spklt within an infl; ped absent or to 4 mm; dis usu above the glm and beneath the flt, smt in the rchs, smt at the infl bases. Spklt usu lat compressed, smt terete, with 1–16 bisex flt, the distal (or only) flt smt strl; rchl smt prolonged beyond the base of the distal flt. Glm unequal to equal, shorter than to longer than the adjacent flt, subulate, lanceolate, rectangular, ovate, or obovate, 1–5-veined, absent or vestigial in some species; flt lat compressed to terete; cal glab or hairy; lm lanceolate to rectangular, stiffly memb to coriaceous, smt keeled, 5(7)-veined, veins not converging distally, inconspicuous, apc entire, lobed, or toothed, unawned or awned, awns tml, unbrchd, lm-awn jnct not evident; pal usu subequal to the lm, smt considerably shorter or slightly longer than the lm; lod 2, without venation, usu ciliate; anth 3; ov with hairy apc; sty 2, bases free. Car ovoid to fusiform, longitudinally grooved, not beaked, pericarp thin; hila linear; emb about 1/3 as long as the car. x = 7. The Triticeae are primarily north-temperate in distribution. The tribe includes 400–500 species, among which are several important cereal, forage, and range species. Its generic treatment is contentious. This reflects the prevalence of natural hybridization, introgression, polyploidy, and reticulate relationships among its species. These factors preclude the circumscription of monophyletic groups, and mitigate against the delineation of morphologically coherent groups. Tsvelev (1975) argued that these same factors contribute to the tribe’s success by maintaining a “generalist” genome. The following key does not include intergeneric hybrids; they are treated in the text on the following pages: ×Triticosecale (p. 56), ×Pseudelymus (p. 60), ×Elyhordeum (p. 61), ×Elyleymus (p. 73), and ×Leydeum (p. 78). In the field, they can usually be detected by their intermediate morphology and sterility. In sterile plants, the anthers are indehiscent, somewhat pointed, and tend to remain on the plants. Measurements of rachis internodes and spikelets should be made at midspike. 1. Spikelets 2–7 at all or most nodes. 2. Spikelets 3 at each node, the central spikelets sessile, the lateral spikelets usually pedicellate, sometimes all 3 spikelets sessile in cultivated plants; spikelets with 1 floret, usually only the central spikelet with a functional floret, the florets of the lateral spikelets usually sterile and reduced, in cultivated plants all florets functional or those of the lateral spikelets functional and those of the central spikelet reduced . . . . . . . . . . . . . . . . . . . . 7.01 Hordeum 2. Spikelets usually other than 3 at each node, if 3, all 3 sessile; spikelets with 1–11 florets, if 1 floret, additional reduced or sterile florets present distal to the functional floret in at least 1 spikelet per node. 3. Plants annual, weedy; spikelets with only 1 seed-forming floret . . . . . . . . . . . . . . . . . . 7.03 Taeniatherum 3. Plants perennial, usually not weedy; spikelets usually with more than 1 seed-forming floret. 4. Lemma awns (0)1–120 mm long; anthers 0.9–6 mm long; blades with wellspaced , unequally prominent veins on the adaxial surfaces. . . . . . . . . . . . . . . . . 7.12 Elymus (in part) 4. Lemmas usually unawned or with awns up to 7 mm long, if awns 16–35 mm long, anthers 6–8 mm; blades usually with closely spaced, equally prominent veins on the adaxial surfaces. 5. Disarticulation in the spikelets, beneath the florets; plants sometimes cespitose, often rhizomatous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.15 Leymus (in part) 5. Disarticulation tardy, in the rachises; plants cespitose, not rhizomatous . . . . 7.17 Psathyrostachys 1. Spikelets...

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