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

PASPALUM/POACEAE
1009
5. Spikelets glabrous.
7. Spikelets relatively rounded (broadly obovate to ovate or suborbicular); inflorescence
usually with 4–12(–15) branches; lemma and palea of fertile florets dark
brown at maturity; upper glume and lemma of lower (sterile) floret brownish ____ P. boscianum
7. Spikelets rather narrow (elliptic to obovate); inflorescence usually with 3–7(–10)
branches; lemma and palea of fertile florets straw-colored or light at maturity; upper
glume and lemma of lower floret greenish to straw-colored or somewhat purplish.
8. Leaf blades usually 3–6 mm wide; spikelets 2.2–2.6 mm long, 1.2–1.5 mm wide;
inflorescence branches usually (1–)1.5–4(–5) cm long; edge of wing of inflorescence
axis sometimes with a few long (3–8 mm) hairs _______________________ P. lividum
8. Leaf blades (4–)6–18 mm wide; spikelets 2.6–3.6 mm long, 1.5–2 mm wide; inflorescence
branches (2–)3–7(–10) cm long; edge of wing of inflorescence axis
without long hairs _________________________________________________ P. pubiflorum
1. Inflorescence branches with axis not broadly winged, if flattened or narrowly winged, then axis
conspicuously narrower than the rows of spikelets.
9. Spikelets with long hairs around the margin, glabrous or short-pubescent on the faces; upper
glume and lemma of sterile floret abruptly pointed beyond the blunt fruit (except in P. conjugatum).
10. Spikelets 1.3–1.7(–1.9) mm long. 0.8–1.1 mm wide, solitary; inflorescence branches 2 or
sometimes 3; species known in East TX only from Liberty Co. on s margin of area ______ P. conjugatum
10. Spikelets 1.8–4 mm long, 1.1–2.5 mm wide, mostly in pairs; inflorescence branches 2–36;
species widespread in East TX.
11. Spikelets 1.7–2.5 mm wide; inflorescence branches 2–8 _________________________ P. dilatatum
11. Spikelets 1.1–1.5 mm wide; inflorescence branches 7–36 ___________________________ P. urvillei
9. Spikelets glabrous or uniformly short- or long-pubescent; upper glume and lemma of sterile
floret not abruptly pointed beyond the fruit.
12. Inflorescence branches usually only 2, these arising at the same point or less than 1 cm
apart (1–2 additional branches occasionally present below the terminal pair).
13. Plants usually of upland habitats; spikelets broadly ovate to broadly elliptic or obovate,
obtuse or broadly acute at apex.
14. Spikelets 2.6–3.6(–4) mm long; leaf sheaths and blades glabrous or nearly so; leaf
blades flat or conduplicate _____________________________________________ P. notatum
14. Spikelets 1.9–2.5 mm long; leaf sheaths and blades (lower ones) often with pubescence;
leaf blades flat _________________________________________________ P. minus
13. Plants typically of wet habitats (except the relatively rare P. almum often in upland
habitats); spikelets narrowly ovate to elliptic, tapering to an acute apex.
15. Plants densely tufted, not extensively spreading, without either creeping rhizomes,
stolons, or culms rooting at the nodes; lower glume absent; upper glume glabrous;
species apparently rare in East TX __________________________________________ P. almum
15. Plants extensively spreading, with creeping rhizomes or stolons or culms rooting
at the nodes; lower glume absent OR present; upper glume glabrous OR pubescent;
including species widespread and common in East TX.
16. Upper glume glabrous; lower glume usually absent; spikelets 3–4.5 mm long;
species primarily of sub-brackish to saline coastal areas in Gulf Prairies and
Marshes, known in East TX only from Jefferson Co. on extreme se margin of
area __________________________________________________________ P. vaginatum
16. Upper glume usually pubescent; lower glume usually present; spikelets
2.4–3(–3.2) mm long; species widespread in East TX _____________________ P. distichum
12. Inflorescence branches (1–)2–numerous, IF only 2, then the branches 1 cm or more apart.
17. Spikelets usually 3.6–4.8 mm long, overlapping; plants usually large, the culms usually
1–2.1 m tall ___________________________________________________________ P. floridanum