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

886 POACEAE/DICHANTHELIUM
5. Spikelets usually 2.1–3 mm long; upper (fertile) floret as long as the beakless upper
glume and lemma of lower floret _________________________________________ D. linearifolium
3. Blades of basal and lowest culm leaves 3–15 times as long as wide (blades of upper culm
leaves up to 20 times), 2–40 mm wide; culms usually branched near the middle in the fall,
with 3–14 leaves well-distributed along the culm above the basal rosette (except in P. laxiflorum
and P. strigosum which have only 2–4 leaves).
6. Spikelets 2.4–5.2 mm long.
7. Nodes with a dense ring of widely spreading to reflexed hairs.
8. Spikelets 2.4–3.2 mm long.
9. Nodes with a broad, conspicuous, glabrous region just below a ring of hairs; culms
usually 80–155 cm tall, stout (usually 2–5 mm thick); leaf blades (7–)9–25(–30) mm
wide ______________________________________________________________ D. scoparium
9. Nodes lacking a broad glabrous region; culms usually 20–80(–100) cm tall, slender
(� 2 mm thick); leaf blades 13 mm or less wide.
10. Culm internodes and leaf sheaths (except margins) usually glabrous; spikelets
2.4(–2.6) mm or less long ________________________________________ D. dichotomum
10. Culm internodes and leaf sheaths with spreading to ascending or appressed
hairs; spikelets 2.4–3 mm long.
11. Culm internodes with appressed to ascending hairs ______________________ D. ovale
11. Culm internodes with spreading hairs.
12. Hairs of culm internodes not papillose-based; leaf blades at mid-culm
mostly 4–8 mm wide; spikelets attenuate basally ____________ D. consanguineum
12. Hairs of culm internodes papillose-based; leaf blades at mid-culm
mostly 8–12 mm wide; spikelets usually not attenuate basally, turgid
____________________________________________________ D. malacophyllum
8. Spikelets 3.6–5.2 mm long.
13. Leaf blades velvety-pubescent beneath, 8–16(–18) mm wide; ligule of hairs 2–
4(–5) mm long; internodes with evident pubescence ________________________ D. ravenelii
13. Leaf blades not velvety-pubescent beneath, glabrous or with only scattered pubescence,
15–26(–40) mm wide; ligule essentially absent or to ca. 1 mm long;
internodes glabrous OR sometimes with pubescence __________________________ D. boscii
7. Nodes glabrous OR with spreading to ascending hairs, but not a dense ring.
14. Leaf blades usually 13 mm or less wide.
15. Spikelets narrowly obovate, gradually tapering to a narrow base (= attenuate),
3.5–4.4 mm long ___________________________________________________ D. nodatum
15. Spikelets ovate, oblong, or slightly obovate, not tapering gradually to a narrow
base, 2.4–4 mm long.
16. Hairs of ligule and adjacent hairs 2–6 mm long.
17. Spikelets usually 2.7–4 mm long; upper glume usually with an orange
or purple spot at base _____________________________________ D. oligosanthes
17. Spikelets 2.4–3 mm long; upper glume usually without an orange or
purple spot at base _______________________________________________ D. ovale
16. Hairs of ligule absent or to 2 mm long.
18. Plants robust, the culms usually 90–150 cm tall; spikelets 2.4–2.9 mm
long; leaf blades usually 15–25 cm long ______________________ D. scabriusculum
18. Plants relatively smaller, the culms 15–85 cm tall; spikelets 2.4–4 mm
long; leaf blades usually 3–15(–20) cm long.
19. Leaf blades cordate-clasping at base; ligule ca. 0.3 mm long; spikelets
1.1–1.3 mm wide __________________________________ D. commutatum
19. Leaf blades not cordate-clasping at base; ligule 0.5–2 mm long;
spikelets 1.1–1.8 mm wide.