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1 Inflorescences spikelike branches, the spikelets partially embedded in the rachises |
1 Inflorescences panicles or spikes (if spikes, the spikelets not embedded. |
..2 Spikelets (at least the terminal) subtended by 1-many stiff, terete bristles. |
....3 Bristles persistent on the inflorescence, each spikelet disarticulating above the bristles |
....3 Bristles falling with the spikelets at maturity (the disarticulation at the base of the fascicles) |
..2 Spikelets not subtended by stiff bristles. |
......4 Inflorescences of spikelike branches 1-3.7 cm long, the branch extending 2.5-4 mm beyond the attachment of the distal spikelets |
......4 Inflorescences not as above. |
........5 Upper florets laterally compressed |
........5 Upper florets dorsally compressed. |
..........6 Lower glumes or lower lemmas awned. |
............ 7 Leaves > 10× as long as wide; ligules absent or of hairs |
............ 7 Leaves < 8× as long as wide; ligules present, membranous or of hairs. |
............ ..8 Lower glumes unawned or very shortly so; upper glumes ciliate-margined; plants erect or basally decumbent |
............ ..8 Lower glumes awned; upper glumes not ciliate-margined; culms trailing; plants strongly trailing, rooting at the nodes |
..........6 Lower glumes and lower lemmas unawned. |
............ ....9 Lemma margins flat, hyaline; lower glumes absent or < ¼ the length of the upper glume. |
............ ......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] |
............ ........11 Inflorescence a narrow panicle with the branches strongly ascending to appressed; spikelets ellipsoid to obovoid; [of Coastal Plain pinelands] |
............ ........11 Inflorescence either a panicle with digitate or subdigitate clusters of spikelike branches or a broad panicle with widely divergent branches; [widespread] |
............ ....9 Lemma margins not hyaline, frequently involute; lower glumes various (absent, < ¼ the length, to longer than the upper glume). |
............ ..........12 Spikelets subtended by a cuplike callus |
............ ..........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. |
............ ............ ..14 Lower (sterile) palea indurate and expanding the spikelet at maturity, as long as the lower (sterile) lemma; lower and upper florets standing apart from one another at maturity; outer surface of the upper (fertile) palea with compound papillae |
............ ............ ..14 Lower (sterile) palea membranous, not expanding the spikelet at maturity, usually shorter than lower (sterile) lemma, or absent; lower and upper florets closely appressed at maturity; outer surface of the upper (fertile) palea lacking compound papillae. |
............ ............ ....15 Inflorescence of 1-sided, spikelike primary branches. |
............ ............ ......16 Spikelets with lower lemmas (and lower glumes, if present) adjacent to the branch axes. |
............ ............ ........17 Lower glumes absent |
............ ............ ........17 Lower glumes present on at least most spikelets |
............ ............ ......16 Spikelets with upper lemmas (and upper glumes, if present) adjacent or appressed to the branch axes. |
............ ............ ..........18 Both glumes absent from all or most spikelets |
............ ............ ..........18 Upper or both glumes present on all spikelets. |
............ ............ ............ 19 Lower glumes usually absent; upper lemmas smooth to slightly rugose |
............ ............ ............ 19 Lower glumes present; upper lemmas rugose and verrucose |
............ ............ ....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 dense, the spikelets obscuring most of the internal branches |
............ ............ ............ ..20 Inflorescences open panicles, or if narrowed, all or nearly all the panicle branches readily visible. |
............ ............ ............ ....21 First glume 5-7.5 mm long, nearly as long as sterile lemma; fertile lemma 1/3 length of sterile lemma; rachilla prolonged between the florets |
............ ............ ............ ....21 First glume shorter, or if this long, then at most 3/4 length of sterile lemma; fertile lemma > ½ the length of the sterile lemma; rachilla not prolonged between the florets. |
............ ............ ............ ......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 tuberculate (or tuberculate-hispid) |
............ ............ ............ ........23 Spikelets smooth, not tuberculate. |
............ ............ ............ ..........24 Panicle < 2 cm wide at maturity. |
............ ............ ............ ............ 25 Spikelets > 4.5 mm long; first glume > 2.4 mm long; ligule 4-6 mm long; [of coastal dunes] |
............ ............ ............ ............ 25 Spikelets < 4 mm long; first glume < 2.1 mm long; ligule < 2 mm long; [not of coastal dunes]. |
............ ............ ............ ............ ..26 Blades involute, 1.5-4 mm wide; culms wiry |
............ ............ ............ ............ ..26 Blades flat, the larger 6-20 mm wide; culms stout. |
............ ............ ............ ............ ....27 Panicles constricted, 0.3-1.6 cm wide; spikelets subsessile to short-pediceled; summit of fertile palea not enclosed by fertile lemma |
............ ............ ............ ............ ....27 Panicles > 1 cm wide; spikelets short to long-pedicelled; summit of fertile palea enclosed by fertile lemma |
............ ............ ............ ..........24 Panicle > 2 cm wide at maturity. |
............ ............ ............ ............ ......28 Fertile lemmas rugose with cross-venation between the main parallel veins |
............ ............ ............ ............ ......28 Fertile lemmas not rugose. |
............ ............ ............ ............ ........29 Lower primary panicle branches in whorls of 4-7 at the nodes, stiffly spreading, naked on the proximal ½, the axils strongly pilose; lower culm internodes appressed papillose-pubescent; first glume acuminate, ½ as long as spikelet; fertile lemma chestnut brown at maturity |
............ ............ ............ ............ ........29 Plants without the above combination of characters. |
............ ............ ............ ............ ..........30 Plants from a cluster of fibrous roots, without rhizomes or hard knotty crowns, annual |
............ ............ ............ ............ ..........30 Plants with rhizomes or hard knotty crowns, perennial. |
............ ............ ............ ............ ............ 31 Plants with hard crowns, lacking rhizomes; fertile lemma 1.2-1.6 mm long |
............ ............ ............ ............ ............ 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 |
............ ............ ............ ............ ............ ..32 Rhizomes less than 1 cm thick with glabrous scale-like leaves; culms not woody. |
............ ............ ............ ............ ............ ....33 First glume truncate apically |
............ ............ ............ ............ ............ ....33 First glume acute to obtuse. |
............ ............ ............ ............ ............ ......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 |
............ ............ ............ ............ ............ ......34 Culms terete; ligules 1-6 mm long; at least some spikelet pedicels spreading, spikelets not at all secund, essentially straight; fertile lemma 2-4 mm long |