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

1004 POACEAE/PAPPOPHORUM
blades broad, 2–7 cm long, 5–22 mm wide, only 4–6 times as long as wide; inflorescence open;
pedicels elongate, 9–20 mm long; spikelets 1–1.4 mm long, with sparse pubescence. Moist
weedy areas; Travis Co. (Turner et al. 2003) near w margin of East TX; also Cameron Co. (Gould
1975b; Turner et al. 2003) at the s tip of TX; in the U.S. known only from TX. Aug–Oct. Native to
Latin America. According to Gould (1975b), this species is “probably not established” in TX. I
Panicum verrucosum Muhl., (warty), WARTY PANICUM, WARTY PANIC GRASS. Glabrous annual with
erect to decumbent culms to 120(–150) cm long; ligule 0.5 mm or less long; leaf blades 3–10 mm
wide; panicle few-flowered; spikelets 1.7–2.2(–2.5) mm long, conspicuously warty, glabrous.
Moist to marshy areas and open woodlands, sandy soils; widespread in Pineywoods and Post
Oak Savannah; e U.S. from MA s to FL w to MO and TX. Jul–Nov. See description of P.
brachyanthum for comparison with that similar species.
Panicum virgatum L., (twiggy, wand-like), SWITCH GRASS. Large rhizomatous perennial 0.6–2(–3)
m tall; nodes glabrous; leaf sheaths usually glabrous; ligule a fringed membrane (1.5–)2–6 mm
long; leaf blades 3–15 mm wide, glabrous or often pilose at base; panicle large, usually 15–55 cm
long, the branches spreading to ascending; spikelets acuminate-pointed, 2.8–5 mm long, usually
gaping open at apex; lower glume � 1/2 as long as spikelet. Low moist areas and prairies;
throughout TX; se Canada and throughout most of the U.S. Aug–Nov. SWITCH GRASS was one of
the dominants in the original tall grass prairie; it is considered one of the “big four” tall grasses
along with Andropogon gerardii, Schizachyrium scoparium, and Sorghastrum nutans. However,
its abundance in native grasslands decreases with grazing (Freckmann & Lelong 2003b). This
species is seen in East TX in two growth forms: 1) LOWLAND SWITCH GRASS—very large isolated
clumps often nearly 2(–3) m tall, usually in low moist areas, and 2) UPLAND SWITCH GRASS—
shorter plants not apparently clumped, with culms more scattered along the creeping rhizomes,
found in drier sites. Davis et al. (1995) pointed out additional differences and suggested
the variation is possibly worthy of taxonomic recognition. The morphological variation seen is
not surprising since the species is quite variable in terms of chromosomal makeup—“plants in a
small area can range from diploid through duodecaploid [12X], with dysploid derivatives”
(Freckmann & Lelong 2003b). While native to North America, this species has been introduced
as a forage species to other parts of the world (Freckmann & Lelong 2003b).
PAPPOPHORUM Schreb. PAPPUS GRASS
AA New World C4 genus of 8 species (Reeder & Toolin 1989; Reeder 2003) ranging from the s
U.S. to Argentina. There has been taxonomic confusion in the past, with the number of species
recognized ranging from 8–20 (Reeder & Toolin 1989). Preliminary molecular data (Hilu & Alice
2001) suggest an affinity with some species of Eragrostis. Salt glands, to dispose of excess
salt, have been observed in two species (as in a number of other species of subfamily
Chloridoideae) (Taleisnik & Anton 1988). (Greek: pappos, pappus, and phoros, bearing, in reference
to the pappus-like crown of the lemma) (subfamily Chloridoideae, tribe Pappophoreae)
REFERENCES: Pensiero 1986; Taleisnik & Anton 1988; Reeder & Toolin 1989; Reeder 2003.
Pappophorum bicolor E. Fourn., (two-colored), PINK PAPPUS GRASS. Tufted perennial to 100 cm
tall; ligule a ring of hairs ca. 1 mm long; leaf blades 5 mm or less wide; inflorescence a contracted
spike-like panicle to ca. 20 cm long, often with some erect-spreading branches, pink or
purplish at maturity; spikelets 6–8(–10) mm long (including numerous awns), composed of 2–3
perfect florets with 1–2 reduced florets above, disarticulating above the glumes, the florets falling
as a unit; lemmas rounded on the back, indistinctly many-veined, with 11–15 awns; bodies
of lower lemmas 2.5–4 mm long; awns variable in length, the longest 2.5–5(–6) mm long, to 1.5
times the length of the lemma body; reduced florets similar to fertile ones but smaller. Grassy
or brushy areas, roadsides, and along streams; Bexar and DeWitt (TAES) cos. near sw margin of
East TX; mainly s and w TX; in the U.S. known only from TX (Reeder 2003); also n Mexico.
Apr–Nov.