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

814 POACEAE
12. Inflorescence so dense that its central axis is usually not visible; spikelets
with 2 easily overlooked, reduced or scale-like sterile lemmas below the
fertile floret _____________________________________________________ Phalaris
12. Inflorescence dense, but not so dense that its central axis is not visible;
spikelets with only 1 floret, no reduced lemmas present.
13. Inflorescence branches dense, but not in whorls; ligule 0.5–1.5(–1.7)
mm long _______________________________________________ Muhlenbergia
13. Inflorescence branches in whorls; ligule 2–7 mm long.
14. Lemmas 1.4–2 mm long; spikelets disarticulating above the
glumes; plants usually stoloniferous, the stolons rooting at the
nodes and often forming a dense mat ______________ Agrostis (A. stolonifera)
14. Lemmas ca. 1 mm long; spikelets disarticulating below the
glumes; plants not stoloniferous _____________________ Polypogon (P. viridis)
10. Glumes, at least the first, shorter than lemma.
15. Spikelets extremely small, 1–2 mm long; glumes deciduous; inflorescences
open, very delicate in appearance; pedicels much longer than spikelets,
2.4–11 mm long; introduced species rare in East TX, known in the area only
from Brazos Co. ___________________________________________ Eragrostis (E. airoides)
15. Spikelets variable in length, 1.3–7(–10) mm long; glumes persistent (except
in Cinna which has spikelets 3.5 mm or more long); inflorescences and pedicels
various; including native and introduced species widespread in East TX.
16. Spikelets disarticulating below glumes; stamen 1 per floret _________________ Cinna
16. Spikelets disarticulating above glumes; stamens 3 per floret.
17. Lemma usually 1-veined (3-veined in two annual species); plants annual
or perennial; fruit dropping from lemma and palea at maturity;
seed loose, not fused to ovary wall; ligule a minute ring of hairs with
membranous base _________________________________________ Sporobolus
17. Lemma 3-veined, the lateral veins sometimes faint; plants perennial;
fruit enclosed in lemma and palea at maturity; seed fused to ovary
wall; ligule a short membrane, usually without hairs _____________ Muhlenbergia
9. Glumes AND/OR lemmas awned.
18. Inflorescence an extremely dense, spike-like panicle.
19. Inflorescences (8–)15–54(–60) cm long; glumes unawned; lemma with awn
3(–4) mm or less long ___________________________________________ Muhlenbergia
19. Inflorescences 1–15(–18) cm long; EITHER glumes awned OR lemmas with
awn 3 mm or more long.
20. Glumes awnless; lemma with awn 3–8+ mm long arising below middle
of back of lemma _____________________________________________ Alopecurus
20. Glumes awned, the awns 0.8–10 mm long; lemma awnless or with an
awn to ca. 1 mm long arising from the apex of the lemma.
21. Awn of glume 0.8–1.5(–2) mm long, abruptly arising from unnotched
apex; inflorescences 5–9(–10) mm wide; lemma awnless _______________ Phleum
21. Awn of glume 4–10 mm long, arising from an apical notch; inflorescences
10–30 mm wide; lemma with a delicate awn 0.5–1 mm long
___________________________________________ Polypogon (P. monspeliensis)
18. Inflorescence usually an open or sometimes contracted panicle, but not extremely
dense and spike-like.
22. Lemmas either awnless OR awned from an entire or very minutely cleft apex;
glumes, at least the first, usually shorter than lemma, awnless or awned.
23. Spikelets disarticulating below glumes; stamen 1 per floret; lemma with
an awn 0.2–1.5 mm long; inflorescence a contracted panicle ________________ Cinna