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

POACEAE
799
rower and often differently awned; awn of lemmas often much shorter (can be up to
15 mm long) or absent ____________________________________________________ Sorghum
3. Spikelets not in pairs; plants sometimes in extensive dense colonies.
7. Spikelets each subtended by 1 or 2 bristles; panicles densely cylindrical, spike-like _________ Setaria
(S. magna)
7. Spikelets not subtended by bristles; panicles neither densely cylindrical nor spike-like.
8. Panicle of 5–75 spike-like, � appressed branches _________________________________ Spartina
8. Panicle branches neither spike-like nor appressed.
9. Spikelets 2.8–5 mm long, glabrous; florets 2 per spikelet (upper perfect, lower staminate);
leaf blades 0.3–1.5 cm wide _________________________________ Panicum (P. virgatum)
9. Spikelets 10–15 mm long, with either rachilla or lemmas hairy; florets 2–10 per
spikelet; leaf blades mostly 1.5–7 cm wide.
10. Lemmas glabrous; rachilla hairy; glumes 3–8(–10) mm long, shorter than the
lowest lemma ____________________________________________________ Phragmites
10. Lemmas hairy; rachilla glabrous; glumes 10–15 mm long, as long as entire
spikelet _____________________________________________________________ Arundo
KEY B
Spikelets fused with or closely fitted into the axis of the inflorescence or inflorescence
branches, forming a solid cylindrical or flattened spike
1. Inflorescences as long as or longer than the leafy portion of the culm, with (3–)4–12 branches
___________________________________________________________________________ Schedonnardus
1. Inflorescences shorter than the leafy portion of the culm, unbranched or with up to 3 branches.
2. Spikelets (at least upper) awned _____________________________________________________ Aegilops
2. Spikelets awnless.
3. Spikelets apparently, but not actually fused with nor closely fitted into the inflorescence
axis, actually only very closely appressed forming a very slender, cylindrical raceme 1.5–2.5
mm in diam. (superficially resembling Coelorachis) _________________________________ Eremochloa
3. Spikelets actually fused with or closely fitted into the inflorescence axis.
4. Plants tufted annuals; spikelets not in pairs; floret 1 per spikelet; inflorescence usually
curved ___________________________________________________________________ Parapholis
4. Plants perennials, often rhizomatous or stoloniferous; spikelets usually in pairs; florets 2
per spikelet; inflorescence usually not curved.
5. Spike-like inflorescences flattened plants creeping, with flowering branches only 10–
30 cm tall ___________________________________________________________ Stenotaphrum
5. Spike-like inflorescences (or if branched, the spike-like branches) not flattened or
flattened only on one side; plants not creeping, 30–300 cm or more tall.
6. Unbranched inflorescences 2–3 mm thick; leaf blades 1.5–8 mm wide __________ Coelorachis
6. Unbranched inflorescences or each of the 2–3(–4) branches 5–8 mm thick; leaf
blades usually 10–25 mm wide ___________________________________________ Tripsacum
KEY C
Spikelets unisexual, the staminate and pistillate spikelets
conspicuously different to the naked eye
1. Spikelets in pairs, one sterile and one fertile, dissimilar, the sterile obscuring the fertile [this taxon
with bisexual spikelets is placed here in the key in case of confusion resulting from the two
different spikelet forms]; inflorescence a dense, ovoid to oblong, head-like, sometimes interrupted
panicle 1–4(–7) cm long; lemmas of fertile florets with awn usually 6–17 mm long _____________ Cynosurus
1. Spikelets not in sterile-fertile pairs; inflorescences various; lemmas of fertile florets awnless or
variously awned.