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

804 POACEAE
KEY E
Spikelets with 2–many perfect florets and thus usually 2–many fruits forming per spikelet;
spikelets sessile, or nearly sessile and so densely crowded as to conceal the short pedicels
1. Spikelets borne on opposite sides of the zigzag, usually flattened, main axis of the inflorescence;
inflorescence unbranched, consisting of a solitary, 2-sided spike or spike-like raceme.
2. Glumes usually 3.6 mm or more wide _________________________________________________ Triticum
2. Glumes 1–3.5 mm wide.
3. Lemmas minutely spiny-ciliate on keel and margins (the hairs visible with the naked eye
and obvious with a hand lens) ______________________________________________________ Secale
3. Lemmas not minutely spiny-ciliate on keel and margins.
4. Spikelets solitary at each node of the inflorescence.
5. Glume 1 per spikelet; spikelets oriented with edge (back of lemmas) facing inflorescence
axis ______________________________________________________________ Lolium
5. Glumes 2 per spikelet; spikelets oriented with side facing inflorescence axis ____________ Elymus
4. Spikelets 2–3 at each node of the inflorescence.
6. Lemmas awnless (glumes can have awns up to 5 mm long); plants 35 cm or less tall;
leaf blades 3 mm or less wide; inflorescences 2–3.5(–4) cm long; perfect florets at
most 1 per spikelet [included here since there can appear to be 2] _____________________ Hilaria
6. Lemmas conspicuously awned OR sometimes awnless; plants usually much � 35
cm tall; leaf blades usually much � 3 mm wide; inflorescences 3–21(–30) cm long;
perfect florets at least 2 per spikelet ____________________________________________ Elymus
1. Spikelets not on opposite sides of a main axis, rather borne all on 1 side or on all sides of the
main axis or its branches; inflorescence usually branched, consisting of 2–many spikes, racemes,
or panicles (condensed to open) OR if inflorescence unbranched, then not distinctly 2-sided.
7. Spikelets in several very dense, 1-sided clusters at the end of branches bare of spikelets in
their lower portions; rare introduced species ___________________________________________ Dactylis
7. Spikelets not borne as above; including common native and introduced species.
8. Spikelets in pairs, one sterile and one fertile, dissimilar, the sterile obscuring the fertile; inflorescence
a dense, ovoid to oblong, head-like, sometimes interrupted panicle 1–4(–7)
cm long ____________________________________________________________________ Cynosurus
8. Spikelets not in pairs; inflorescences various, but often more than 7 cm long OR with easily
observed branches.
9. Plants usually 5–30 cm tall; inflorescences usually 1–12 cm long and 19 mm or less
wide.
10. Spikelets usually with 3–4 florets, falling as a unit; inflorescences usually 1–3(–4.5)
cm long, overtopped by the upper leaves; lemmas prominently 5(–7)-veined, the
lowest lemma ca. 4.5–6 mm long _________________________________________ Sclerochloa
10. Spikelets with (4–)5–14 florets, disarticulating above glumes and between florets;
inflorescences usually 3–12 cm long, exserted beyond the upper leaves; lemmas 3veined
or obscurely veined, the lowest lemma ca. 2–3.1 mm long.
11. Plants annual; leaf blades 1–3(–4) mm wide; inflorescences usually branched,
5–15 mm wide; introduced species of roadsides, railroads, and other disturbed
areas _____________________________________________________________ Desmazeria
11. Plants perennial; leaf blades 0.2–1.1 mm wide; inflorescences unbranched, 1.5–
2.5(–3.5) mm wide; native species of shallow soils on granite and other igneous
outcrops or on limestone ______________________________________________ Tripogon
9. Plants usually much larger; inflorescences often much larger.
12. Spikelets borne crowded on all sides of the inflorescence axis or on short, crowded
branchlets, the whole inflorescence narrow, often a dense spike or spike-like or
head-like.