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

1014 POACEAE/PASPALUM
Abundant weed in disturbed sites, lawns, and roadsides; throughout TX; widespread in s 1/2 of
the U.S., also OR. May–Nov. Native of South America (Brazil and Argentina). This species is reported
to be commercially important as a forage crop in the tropics (Yatskievych 1999), but it is
sometimes a troublesome weed (Clayton & Renvoize 1986). Ergot alkaloids can be present—see
generic synopsis. While almost all grasses are wind-pollinated, this grass is unusual in sometimes
being pollinated at least partially by halictid bees (Adams et al. 1981). � I
Paspalum dissectum (L.) L., (dissected, deeply cut), MUDBANK PASPALUM, MUDBANK CROWN GRASS.
Mat- or clump-forming perennial without conspicuous rhizomes; culms 15–60 cm long; leaf
sheaths glabrous; ligule 1.5–2.5 mm long; inflorescence branches 2–6, 1–3(–5.3) cm long, the
branch axes broadly winged, sometimes almost leaf-like, as wide or wider than the rows of
spikelets, the wing margins sometimes even slightly wrapping around the spikelets; spikelets
solitary (with neither aborted spikelet nor pedicel present immediately beside or below fertile
spikelet), in 2 rows, 1.7–2.1(–2.3) mm long; lower glume absent; upper glume minutely pubescent;
lemma of sterile floret glabrous. Lake shores, ditches, sandy soils; Leon (BRIT), Harris
(SBSC), Guadalupe, Montgomery (Morrone et al. 1996), Angelina, Bastrop, Caldwell, Gonzales,
and Nacogdoches (Turner et al. 2003) cos.; also Gulf Prairies and Marshes; e U.S. from NJ s to FL
w to KS and TX. Jul–Nov. [Panicum dissectum L.] This species can have cleistogamous spikelets
with very small anthers (ca. 0.3 mm long); such spikelets do not open to expose the anthers and
stigmas and are thus self-pollinated (Morrone et al. 1996).
Paspalum distichum L., (two-spiked), KNOT GRASS, ETERNITY GRASS, JOINT GRASS, FORT THOMPSON
GRASS, JOINTED CROWN GRASS, THOMPSON GRASS. Perennial 10–65 cm tall, with trailing and rooting
culms (stolons) sometimes several meters long; leaf sheaths usually glabrous or pilose;
ligule 0.6–2 mm long; inflorescence branches 2, occasionally 3–4, these usually paired or one
slightly below other, 1–5(–7) cm long, the branch axes only slightly winged; spikelets 2.4–3(–3.2)
mm long, mostly solitary, usually in 2 rows; lower glume often present, reduced; upper glume
usually minutely pubescent; lemma of sterile floret glabrous. Moist or wet areas along ponds,
lakes, streams, and ditches; throughout TX; s 1/2 of the U.S., also NJ, OR, and WA. Jun–Oct.
[Digitaria paspaloides Michx., P. distichum var. indutum Shinners, P. paspaloides (Michx.)
Scribn.] While some authorities (e.g., Jones et al. 1997) recognize var. indutum (known only
from Dallas Co.—Gould 1975b) with leaf sheaths pubescent, we are following Allred (1982),
Allen (1992b), Kartesz (1999), and Allen and Hall (2003) in not recognizing infraspecific taxa.
Larry Brown (pers. comm.) notes that the upper glume can be pubescent on some spikelets but
glabrous on others (on the same plant) and that likewise the first glume can be either present or
absent—these conditions suggest that the species should perhaps be merged with P. vaginatum.
Paspalum floridanum Michx., (of Florida), FLORIDA PASPALUM, BIG FLORIDA PASPALUM, BIG
PASPALUM, FLORIDA CROWN GRASS. Rhizomatous perennial; culms erect, usually 1–2.1 m tall; leaf
sheaths and blades nearly or completely glabrous or � densely hirsute; ligule 1–3.3 mm long;
inflorescence branches usually 2–5(–8), 3–13(–17) cm long, the branch axes � unwinged; spikelets
usually 3.6–4.8 mm long, mostly paired, in 4 rows, glabrous; lower glume absent. Grasslands
and open woodlands; widespread in e 1/3 of TX; e U.S. from NJ s to FL w to KS and TX.
Aug–Nov. [Paspalum floridanum var. glabratum Engelm. ex Vasey] Some authorities (e.g., Jones
et al. 1997; Yatskievych 1999; Hatch 2002) recognize var. glabratum, based on � glabrous leaf
sheaths and blades (versus with pubescence). However, we are following Allen and Hall (2003)
in not recognizing infraspecific taxa.
Paspalum hartwegianum E. Fourn., (for Theodore Hartweg, 1812–1871, Royal Horticultural Society
collector in CA and Mexico), HARTWEG’S PASPALUM, HARTWEG’S CROWN GRASS. Tufted perennial
similar to P. pubiflorum; inflorescence branches (3–)4–8, 3–7 cm long, the branch axes
winged; spikelets (2.2–)2.5–2.9(–3.2) mm long, typically paired, usually in 4 rows on the branch
axis; lower glume absent; upper glume and lemma of sterile floret pubescent. Ditches, low areas;