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1 Fertile spikelets variously spiny or bead-like. | |
2 Pistillate spikelets concealed within a hard, beadlike shell, this white, black, or variously colored; [tribe Andropogoneae] | |
3 Bur formed from accrescent branchlets, with fewer and less regularly arranged straight prickles (these typically retrorsely scabrous); [tribe Paniceae] | |
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2 Spikelets (at least the terminal) subtended by 1-many stiff, terete bristles. | |
5 Upper florets dorsally compressed. | |
7 Leaves < 8× as long as wide; ligules present, membranous or of hairs. | |
10 Subterranean (cleistogamous) inflorescences present; aerial inflorescences with elongate rachises; spikelets of the aerial inflorescences often sterile; spikelets glabrous; leaves either with a white cartilaginous margin or prominently ciliate; [of the Coastal Plain] | |
10 Subterranean inflorescences absent; aerial inflorescences either with digitate or subdigitate branches and glabrous spikelets, or with elongate rachises and conspicuously pubescent spikelets; spikelets of the aerial inflorescences fertile; spikelets glabrous, ciliate, or pubescent; leaves various (often not as above); [collectively widespread] | |
12 Spikelets not subtended by a cuplike callus. | |
13 Leaves primarily lacking ligules (at least the upper, and often all, leaves without ligules, if vestigial ligules present, these of hairs) | |
13 Leaves with ligules, these either membranous or of hairs. | |
15 Inflorescence of 1-sided, spikelike primary branches. | |
16 Spikelets with lower lemmas (and lower glumes, if present) adjacent to the branch axes. | |
15 Inflorescence either paniculate with well-developed secondary branchlets or if the primary branches spikelike, then the spikelets not borne in a 1-sided arrangement on the spicate branches. | |
20 Inflorescences open panicles, or if narrowed, all or nearly all the panicle branches readily visible. | |
22 Plant developing a terminal (“spring”) inflorescence usually before mid-summer, followed by lateral (“autumnal”) inflorescences from lower, mid, and/or upper nodes, these often included or hidden among the fascicles of smaller “autumnal” leaves; often developing a rosette of overwintering basal leaves | |
22 Plant developing a terminal inflorescence usually after mid-summer, the lateral inflorescences, when present, from the upper nodes, usually appearing at the same time as the terminal panicle, and not hidden by dense fascicles of smaller leaves; plants lacking a rosette of overwintering basal leaves. | |
23 Spikelets smooth, not tuberculate. | |
24 Panicle < 2 cm wide at maturity. | |
27 Panicles constricted, 0.3-1.6 cm wide; spikelets subsessile to short-pediceled; summit of fertile palea not enclosed by fertile lemma | |
24 Panicle > 2 cm wide at maturity. | |
28 Fertile lemmas not rugose. | |
31 Plants with rhizomes; fertile lemma 1.6-4 mm long. | |
32 Rhizomes about 1 cm thick with pubescent scale-like leaves; lower portion of culm hard, nearly woody | |
34 Culms slightly compressed below; ligules 0.5 mm long or less; spikelet pedicels appressed, the spikelets subsecund, usually some obliquely bent above the first glume; fertile lemma 1.8-2.2 mm long | |