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

800 POACEAE
2. Spikelets with 16–40(–60) florets __________________________________________ Eragrostis (E. reptans)
2. Spikelets with 1–6(–10) florets.
3. Spikelets with 3–6(–10) florets, conspicuously long-hairy (pistillate) or inconspicuously longhairy
(staminate); plants 20–60(–85) cm tall __________________________________ Poa (P. arachnifera)
3. Spikelets with 1–2 florets, glabrous or nearly so; plants either 30 cm or less tall or 30 cm–
4(–5) m tall/long.
4. Plants low, 30 cm or less tall, mat-forming, usually dioecious (= staminate and pistillate
spikelets on different plants) ___________________________________________________ Buchloe
4. Plants usually much larger, not mat-forming, usually monoecious (= staminate and pistillate
spikelets on the same plant).
5. Pistillate spikelets enclosed within a nearly globose, hard, bead-like involucre, with
the staminate portion of the inflorescence extending beyond the apical opening of
the involucre _________________________________________________________________ Coix
5. Pistillate spikelets not within a globose involucre.
6. Staminate and pistillate spikelets in separate inflorescences; pistillate spikelets in
large “cobs”; whole pistillate inflorescence covered by large, leaf-like, modified leaves
or bracts (= shucks or husks) ___________________________________________________ Zea
6. Staminate and pistillate spikelets in the same inflorescence; whole inflorescence
not covered by leaf-like shucks.
7. Leaf blades 4 mm or less wide; glumes absent; inflorescence 7 cm or less long,
inconspicuous, with 1–few spikelets _______________________________________ Luziola
7. Leaf blades (5–)10–80 mm wide; glumes present; inflorescence 10 cm or more
long, often much more, conspicuous, with numerous spikelets.
8. Inflorescence unbranched and spike-like or with 2–3(–4) spike-like branches;
pistillate spikelets becoming very hard; plants terrestrial __________________ Tripsacum
8. Inflorescence a much-branched panicle; pistillate spikelets not becoming
hard; plants usually growing in shallow water.
9. Staminate and pistillate spikelets on different branches, the staminate on
lower branches, the pistillate on upper branches; pistillate spikelets 7–25
mm long; culms completely submersed OR emergent from water;
species rare in East TX, confirmed only for Hays Co. _______________________ Zizania
9. Staminate and pistillate spikelets on the same branches, the pistillate terminal,
the staminate below; pistillate spikelets 4–8 mm long; culms emergent
from water; species widespread in East TX _______________________ Zizaniopsis
KEY D
Spikelets with 2–many perfect florets and thus usually 2–many fruits
forming per spikelet; spikelets pedicelled (pedicels may be short)
1. Lemmas 1-awned from the back (not from their apex).
2. Spikelets (excluding awns) 2.5 mm long or shorter __________________________________________ Aira
2. Spikelets (excluding awns) 3 mm long or longer (often much longer).
3. Glumes 1.5–5 mm long, ca. as long as the individual lemmas (excluding awns) ______________ Trisetum
3. Glumes 18–32 mm long, longer than the individual lemmas (excluding awns) and usually
exceeding all of the lemmas ________________________________________________________ Avena
1. Lemmas awnless or awned from their apex (awn can arise between apical teeth).
4. Glumes conspicuously longer than individual lemmas (excluding awns) and usually exceeding
all of the lemmas.
5. Spikelets 18–32 mm long (excluding awns); lemmas 14–19 mm long _______________________ Avena
5. Spikelets 4–18(–20) mm long (excluding awns); lemmas 2–9 mm long.
6. Lemmas awnless (but with minute mucros � 1 mm long); spikelets 4–7 mm long; inflorescences
10–36 cm long ________________________________________________ Tridens (strictus)