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

POACEAE
805
13. Inflorescences narrow but not dense, the main axis clearly visible at a glance
(spikelets crowded on well-separated short side branches); lowermost floret
sterile, its lemma not very different from glumes in size or appearance _____ Chasmanthium
13. Inflorescences dense, the main axis often obscured by the numerous spikelets;
lowermost floret perfect, its lemma sometimes quite different from glumes in
size or appearance.
14. Lemma veins pubescent, at least in lower portion, or base of lemma longhairy;
spikelets with 3–12 florets ________________________________________ Tridens
14. Lemma veins and base of lemma glabrous or nearly so; spikelets with 2–6
florets.
15. Upper glume widest near apex, abruptly narrowing to a broadly acute
to rounded apex; disarticulation below glumes __________________ Sphenopholis
15. Upper glume widest near middle, gradually narrowing to an acute apex;
disarticulation above glumes.
16. Lemmas awnless; main inflorescence axis and branches puberulent;
inflorescence dense, but interrupted at base; plants perennial ________ Koeleria
16. Lemmas with awn 1–3 mm long arising from between two minute
apical teeth; main inflorescence axis and branches glabrous or nearly
so; inflorescence dense, not interrupted at base; plants annual ________ Rostraria
12. Spikelets borne on 1 side of the inflorescence axis or its branches, often in 2 distinct
rows, the inflorescence with 2–many, distinct, short or long, digitately arranged or
scattered, usually spike-like branches.
17. Branches of inflorescence distributed (scattered) along main axis, usually only 1
arising per node, not crowded together.
18. Panicles open to sometimes highly contracted, even spike-like in overall
appearance, but distinct spike-like branches not present __________________ Eragrostis
18. Panicles of distinct spike-like branches.
19. Spikelets not crowded on branches, the adjacent spikelets usually not
overlapping __________________________________________________ Eragrostis
19. Spikelets often rather crowded, the adjacent spikelet usually overlapping.
20. Lower glume distinctly longer than the lowest lemma, sometimes
even exceeding the distal lemmas; lemmas of fertile florets ciliate
on and adjacent to midsections of lateral veins, the hairs stiff ______ Trichoneura
20. Lower glume shorter than to only slightly longer than the lowest
lemma; lemmas glabrous or with pubescence, but not ciliate on
and adjacent to lateral veins _________________________________ Leptochloa
17. Branches of inflorescence digitate (all arising together at very tip of flowering
culm) or nearly so OR verticillate (in whorls).
21. Lemmas and glumes awnless _________________________________________ Eleusine
21. Lemmas and/or glumes with awns.
22. Axis of each spicate inflorescence branch projecting as a stiff point beyond
terminal spikelet; spikelets with 3–5 perfect florets _________ Dactyloctenium
22. Axis of each spicate inflorescence branch not projecting as a stiff point
beyond terminal spikelet; spikelets with 1–2 perfect florets.
23. Lemma of perfect floret(s) with 3 awns, the central awn 8–12 mm
long, the lateral awns 1.5 mm or less long ________________________ Trichloris
23. Lemma of perfect floret(s) with a single awn _______________________ Chloris