keys to the vascular plants of east texas - Botanical Research ...

POACEAE
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12. Lemma awnless; inflorescence branches 1–3.2(–7) cm long ___________________ Imperata
9. Sessile and pedicellate spikelets different, the sessile ones fertile, the pedicellate ones staminate
or neuter and morphologically different, typically shorter, narrower, or differently awned,
often rudimentary or vestigial.
13. Spikelets awnless.
14. Leaf blades 3–6(–8) mm wide; sessile spikelets 2.5–4 mm long; pedicels and internodes
of inflorescence branches with a central translucent groove, densely villous
with hairs 4–6 mm long, the hairs obscuring the spikelets and obvious at a glance.
_______________________________________________________ Bothriochloa (B. exaristata)
14. Leaf blades 8–60 mm wide; sessile spikelets 3.5–5.5(–9) mm long; pedicels and
internodes of inflorescence branches without a translucent groove, variously pubescent,
but without dense long hairs 4 mm or more long, the spikelets not
obscured _____________________________________________________________ Sorghum
13. Spikelets with awns.
15. Inflorescences � triangular clusters (of 1-several short, almost spikelet-like racemes)
from the upper nodes (many clusters per culm), often drooping, the clusters each
subtended by a reddish spathe-like sheath, each cluster subunit (raceme) with 2
pairs of sterile or staminate, sessile, awnless spikelets at base, forming what appears
to be a loose involucre below the rest of the raceme (which consists of sessile
fertile and pedicellate sterile or staminate spikelets); introduced species known in
East TX only from one collection in Travis Co. _________________________________ Themeda
15. Inflorescences not as above; including species widespread in East TX.
16. Inflorescence a single spike-like raceme per peduncle (each terminal branchlet
with a single raceme above the uppermost leaf, these sometimes crowded
together and sometimes appearing axillary due to the shortness of the
branches of the flowering stem) ____________________________________ Schizachyrium
16. Inflorescence a panicle or of 2 or more racemes or spikes per peduncle (each
terminal branchlet with 2–many inflorescence branches, racemes, or spikes
above the uppermost leaf ).
17. Pedicelled spikelets ca. the same size as the sessile spikelets or only slightly
smaller.
18. Pedicelled spikelet broadly rounded or obtuse at apex; sessile spikelets
2.5–5 mm long; inflorescences mostly terminal, the axillary inflorescences
few or absent _____________________________________ Dichanthium
18. Pedicelled spikelet tapering to a narrow apex; sessile spikelets 7–11
mm long; inflorescences usually both terminal and axillary _________ Andropogon
(A. gerardii)
17. Pedicelled spikelets clearly smaller (either shorter or narrower, usually rudimentary
or vestigial) than the sessile spikelets.
19. Leaf blades cordate-clasping at base; plants low annuals creeping and
rooting at lower nodes _________________________________________ Arthraxon
19. Leaf blades not cordate-clasping at base; plants usually erect perennials
or annuals.
20. Pedicels and usually upper internodes of inflorescence branches
strongly flattened and grooved on both sides, the central portion
thus thin to membranous, often easily ruptured with a probe ____ Bothriochloa
20. Pedicels and internodes of inflorescence branches neither strongly flattened
nor grooved on both sides (can be slightly flattened or grooved
on one side), the central portion thus neither thin nor membranous.
21. Inflorescence appearing digitate and often pinkish purple
when seen in mass, typically well-exserted above uppermost