Grasses of the Intermountain Region

PANICEAE

14. PANICEAE 235 1. Glumes usually conspicuously unequal; lower glumes usually greatly exceeded by the upper floret; upper glume from subequal to longer than the distal floret; lemma of the upper floret usually coriaceous to indurate; disarticulation usually beneath the glumes, not in the axes of the inflorescence branches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14. Paniceae 1. Glumes usually subequal, usually exceeding and concealing the florets; lemmas of the upper florets hyaline to membranous; disarticulation frequently in the axes of the inflorescence branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15. Andropogoneae 14. PANICEAE R. Br. Mary E. Barkworth Pl ann or per; habit various. Clm 3–800 cm, ann, usu not woody. Lvs bas and/or cauline; shth usu open; lig of hairs or memb, memb lig often ciliate, cilia smt longer than the memb base; bld occ psdpet, seldom dis at maturity. Infl tml, smt also axillary, occ subterranean pan; br smt spikelike and secund, smt less than 1 cm; dis usu below the glm, smt at the base of the pan br, occ below the flt. Spklt usu dorsally compressed, varying to terete or lat compressed, with 2(3) flt, lo flt stmt, strl, or rdcd, up flt usu bisex; cal not developed. Glm usu memb; lo glm usu less than ½ as long as the spklt, smt absent; up glm usu subequal to the up flt, occ absent; lo lm similar to the up glm in length and texture; up lm indurate, coriaceous, or cartilaginous, with a germination flap at the base, mrg usu widely separated and involute at maturity, smt flat and hyaline; up pal similar to the up lm in length and texture; lod short; anth usu 3; stigmas usu red. Car usu dorsally compressed or terete; emb ½ or more the length of the car. x = 9, 10. The tribe Paniceae includes about 100 genera and 2000 species and is primarily tropical in distribution. Within the Intermountain Region, it is represented by 13 genera and 46 species. The tribe is so morphologically distinct that it was first recognized, in essentially its current sense, by Robert Brown in 1814. Its primary distinguishing features are the unusual spikelet structure combined with the indurate to coriaceous upper florets. The germination flap is a small soft tissue at the base of the upper lemma through which the primary root of the seedling grows. 1. Inflorescences spikelike panicles, with the branches partially embedded in the flattened rachises; plants perennial, stoloniferous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.11 Stenotaphrum 1. Inflorescences panicles, sometimes spikelike, but the branches not embedded in the rachises or the rachises not flattened; plants annual or perennial, sometimes stoloniferous. 2. Most spikelets or groups of 2–11 spikelets subtended by 1–many, distinct to more or less connate, stiff bristles or bracts. 3. Bristles persistent; disarticulation below the spikelets . . . . . . . . . . . . . . . . . . . . . . . 14.09 Setaria (in part) 3. Bristles falling with the spikelets at maturity; disarticulation at the base of the reduced panicle branches (fascicles). 4. Bristles plumose or antrorsely scabrous, free or fused no more than ½ their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14.07 Pennisetum 4. Bristles glabrous, smooth, retrorsely scabrous, or strigose, usually at least some bristles fused for more than ½ their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.08 Cenchrus 2. All or most spikelets not subtended by stiff bristles, sometimes the terminal spikelet on each branch subtended by a single bristle, and occasionally other spikelets with a single subtending bristle. 5. Terminal spikelet on each branch subtended by a single bristle; other spikelets occasionally with a single stiff subtending bristle . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.09 Setaria (in part) 5. None of the spikelets subtended by a stiff bristle. 6. Lower glumes or lower lemmas awned, sometimes shortly so (the awn reduced to a point in Echinochloa colona) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.02 Echinochloa (in part) 6. Lower glumes and lower lemmas unawned. 7. Upper lemmas and paleas cartilaginous and flexible at maturity; lemma margins flat, hyaline; lower glumes absent or to ¼ the length of the spikelets . . . . 14.01 Digitaria 7. Upper lemmas and paleas chartaceous to indurate and rigid at maturity; lemma margins not hyaline, frequently involute; lower glumes varying from absent to subequal to the spikelets or extending beyond the distal floret. 8. Spikelets subtended by a cuplike callus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.06 Eriochloa 8. Spikelets not subtended by a cuplike callus. 236 14. PANICEAE 9. At least the upper leaves, often all leaves, without ligules; ligules, when present, of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.02 Echinochloa (in part) 9. All leaves with ligules, ligules membranous or of hairs. 10. Paniclebranchesnot1-sided,usuallywithwell-developedsecondary branches; inflorescences sometimes spikelike. 11. Lemmas of upper florets transversely rugose. . . . . . . . . . . . . . . . . 14.13 Zuloagaea 11. Lemmas of upper...