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

POACEAE
813
20. Basal leaves usually different from those of the culm, usually forming
a basal rosette; small axillary panicles on reduced lateral shoots
present in fall; branches typically developing at lower and middle
stem nodes in summer, these branches often rebranching by fall;
plants perennial (sometimes treated as Panicum subgenus
Dichanthelium) _______________________________________ Dichanthelium
20. Basal leaves usually similar to those of the culm but smaller, a basal
rosette absent; small axillary panicles absent in fall; branches usually
not developing at lower and middle stem nodes or, if present,
rarely rebranched; plants annual or perennial _____________________ Panicum
KEY I
Spikelets with 1 fertile floret; reduced floret below fertile floret absent;
spikelets not borne along 1 side of the inflorescence branches;
inflorescences usually without distinct spike-like branches having spikelets to very base
1. Glumes absent, the caryopsis (= fruit) thus subtended by only 2 scale-like bracts (lemma and
palea); inflorescence a panicle with spreading branches.
2. Lemmas awnless; spikelets strongly laterally compressed, 1.3–5.5 mm long, bisexual ____________ Leersia
2. Lemmas awned; spikelets not strongly laterally compressed, 4–25 mm long, unisexual, the
staminate and pistillate either on different branches or in different places on the same branch.
3. 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
3. 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
and common in East TX _________________________________________________ Zizaniopsis
1. Glume(s) present, the caryopsis thus subtended by more than 2 scale-like bracts (lemma, palea,
glume(s)); inflorescence various.
4. Spikelets 7–11 mm long, 2–4 mm wide, strongly flattened, oblong-ovate; glumes much smaller
than lemmas, at most 3 mm long ______________________________________________________ Oryza
4. Spikelets not as above; glumes various.
5. Lemma hard, permanently enclosing caryopsis, narrowly fusiform-cylindrical (shaped like
a fat needle broadest near middle), with a sharp-pointed callus at base, with either 1 very
long (3.5–10 cm) awn OR 3 awns.
6. Lemma with 3 awns; base of awns without ring of hairs _______________________________ Aristida
6. Lemma with 1 awn; base of awn with ring of hairs.
7. Lemma margins strongly overlapping; lemma apex with smooth white neck (= crown)
ca. 0.6–1(–2) mm long; ligule 1 mm or less long __________________________________ Nassella
7. Lemma margins involute, not overlapping (though abutting); lemma apex without
white neck; ligule (0.4–)1.5–4.5 mm long __________________________________ Piptochaetium
5. Lemma neither hard nor permanently enclosing caryopsis, variously shaped, but not as
above, usually without a sharp-pointed callus, with a single awn less than 3.5 cm long or
awnless.
8. Glumes usually 25–30 mm long ___________________________________________ Avena (A. sativa)
8. Glumes 10 mm or less long.
9. Glumes and lemmas both awnless.
10. Glumes both as long as or longer than lemma.
11. Panicles open, not spike-like, 2–25 cm wide _______________________________ Agrostis
11. Panicles dense, almost spike-like, 3 cm or less wide.