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

808 POACEAE
bract/leaf; leaf blades 2–4.5 mm wide; pedicelled spikelet
about as long as sessile spikelet (though narrower) _________ Bothriochloa
(B. ischaemum)
21. Inflorescence appearing digitate or paniculate, variously colored,
closely subtended by a bract/leaf or exserted; leaf blades
0.8–60 mm wide; pedicelled spikelet ranging from about as
long as sessile spikelet to much shorter or represented by the
pedicel only.
22. Inflorescences of 2–7 digitately arranged branches per peduncle
(there can be numerous axillary as well as terminal
inflorescences); leaf blades 0.8–10 mm wide ___________ Andropogon
22. Inflorescences of numerous paniculately arranged
branches per peduncle (the inflorescence can be open or
compact); leaf blades 8–60 mm wide ____________________ Sorghum
KEY G
Spikelets in pairs or not, but usually not in sessile-pedicelled pairs, when spikelets paired,
the glumes thinner than lemmas of fertile florets; fertile spikelets
with 1 perfect floret; lower glume usually shorter than the upper, sometimes missing;
pedicels glabrous or evenly pubescent on all sides, or pedicels absent
1. Upper glume with 3–5 rows of stout hooked prickles ________________________________________ Tragus
1. Upper glume without stout hooked prickles.
2. Spikelets surrounded by a bur-like involucre of prickly spines OR smooth scales OR subtended
by an involucre of 1–many bristles.
3. Involucre of spines or scales that are flattened at least at base (except not flattened in
Cenchrus myosuroides), these sharply prickly (except in Buchloe); spines and bristles, if present,
usually retrorsely barbed.
4. Involucres smooth, neither prickly nor painful to the touch, usually hidden within leafy
portion of plant _____________________________________________________________ Buchloe
4. Involucres sharply prickly, very painful to the touch (SANDBURS), usually conspicuous in
spike-like inflorescence, not hidden in leafy portion of plant _________________________ Cenchrus
3. Involucre of 1–many bristles (not flattened), these not sharply prickly; bristles often antrorsely
barbed, sometimes long ciliate to plumose.
5. Bristles remaining with the inflorescence axis when the spikelets fall; disarticulation below
the individual spikelets, the spikelets falling separately (but spikelets can be very
crowded) ___________________________________________________________________ Setaria
5. Bristles falling with the spikelets; disarticulation below reduced panicle branches (fascicles),
the 1–12 spikelets of a fascicle falling together ____________________________ Pennisetum
2. Spikelets without a well-developed involucre of spines, scales, or bristles (but may have a
minute collar-like or cup-like structure just under the spikelet).
6. Terminal spikelet on each branch immediately subtended by a single bristle, a few other
spikelets sometimes subtended by a single bristle __________________________ Setaria (S. reverchonii)
6. None of the spikelets subtended by a bristle.
7. Reduced floret or florets present below the perfect floret (the reduced ones staminate
or sterile, sometimes represented only by a sterile lemma).
8. Lemma of lowermost sterile floret with ear-like appendages at base; species a rare
introduction in East TX, known only from Falls Co. ________________________________ Ehrharta
8. Lemma of sterile floret without ear-like appendages at base; including species widespread
and common in East TX.
9. Upper glume with awn 3.5–4 mm long divergent � at right angle to glume body;