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

832 POACEAE/ARTHRAXON
A. purpurea; however, “the length of its glumes, the width of its lemma apex, and the length
and thickness of its awns distinguish it from all the other varieties” (Allred 2003d). Allred
(2003d) noted that the callus and awns are particularly problematic for sheep and cattle.
var. nealleyi (Vasey) Allred, (for Greenleaf Alley Nealley, 1864–1896, botanist), BLUE THREEAWN,
NEALLEY’S THREEAWN. Panicles contracted; glumes unequal, the lower glume about half as long
as upper; lemma 7–12(–13) mm long, usually slightly (1–3 mm) longer than upper glume, narrowing
to ca. 0.1 mm wide, the lemma apex twisted into awn column 1–4 mm long; lemma
awns slightly unequal, 15–20(–30) mm long. Grasslands on rocky, usually limestone soils;
Travis Co. (BRIT; Carr 2002a) near w margin of East TX; w 2/3 of TX; mainly sw U.S. from KS
and TX w to CA, also IL and VT. May–Oct. [A. glauca (Nees) Walp.] Turner et al. (2003) combined
this taxon and A. purpurea var. wrightii and treated them as A. glauca. However, we are
following the recent treatment in Flora of North America (Allred 2003d) in recognizing them
as varieties of A. purpurea. According to Allred (2003d), “Although var. nealleyi is more distinct
than the other varieties, having tight tufts of foliage exceeded by narrow, straw-colored
panicles, it grades into var. purpurea, and the panicles resemble those of var. wrightii.”
var. purpurea, (purple), PURPLE THREEAWN, PURPLE NEEDLE GRASS. Panicles open, curving, the
branches flexuous; glumes unequal, the second 11–15 mm long, to twice the length of the first;
lemma usually 10–12 mm long, narrowing to 0.1–0.3 mm wide at apex; lemma awns about
equal, 3–4.5 cm long. Sandy or rocky soils; Post Oak Savannah s and w through much of w 3/4
of TX; sw U.S. from AR and LA w to CA. Apr–Oct.
var. wrightii (Nash) Allred, (for Charles Wright, 1811–1885, TX plant collector), WRIGHT’S
THREEAWN, WRIGHT’S TRIPLEAWN GRASS. Panicles contracted; glumes unequal, the second 11–15
mm long, the first 0.5–0.75 as long as second; lemma equaling or exceeding upper glume, usually
11–15.5 mm long, narrowing to 0.2–0.3 mm wide at apex; lemma awns about equal, 15–30
mm long, the central occasionally longer than laterals. Calcareous soils; Blackland Prairie s and
w through much of w 3/4 of TX; sw U.S. from OK and TX w to CA. May–Oct. [A. wrightii Nash]
According to Allred (2003d), “It is the most robust variety of A. purpurea, and has dark, stout
awns and long panicles. It may be confused with var. nealleyi, which has narrower lemmas and
awns and a light-colored panicle, but it also intergrades with var. purpurea …”
Aristida ramosissima Engelm. ex A. Gray, (much-branched), S-CURVE THREEAWN. Annual,
much-branched, similar to A. oligantha (inflorescence few-flowored; spikelets large); lower
glume 11–20 mm long, upper glume usually 16–25 mm long, including 3–7 mm long awn;
lemma (8–)14–25 mm long; central lemma awn 9–28 mm long, with a semicircular bend at
base; lateral lemma awns very short, 0–7 mm long, erect or nearly so. Sandy soils; roadsides,
fields, open dry areas; Robertson, Van Zandt (BRIT), and Freestone (Turner et al. 2003) cos. in
the Post Oak Savannah; rare in TX (e.g., Gould 1975 indicated that he had seen no TX collections);
also reported for the Pineywoods and Edwards Plateau by Hatch (2002); c U.S. from IN to
IA s to LA and TX. Late summer–fall. While not officially designated as such (e.g., TOES 1993;
Carr 2002d; Poole et al. 2002), given its limited distribution in the state, we consider this species
to be of conservation concern in TX. �
ARTHRAXON P. Beauv. CARP GRASS
AA genus of 7 species (Thieret 2003c) of small grasses native to tropical and subtropical areas
of the Old World. Like all members of the Andropogoneae, it is characterized by C4 photosyn
thesis (Watson & Dallwitz 1999; Kellogg 2000a). While monophyletic, delimitation of species
within the genus is “quite difficult” (van Welzen 1993). “The spikelets break off easily and remain
stuck to clothes and hair…” (van Welzen 1993). (Greek: arthron, joint, and axon, axis, in reference
to the jointed inflorescence axis) (subfamily Panicoideae, tribe Andropogoneae)
REFERENCES: Kiger 1971; van Welzen 1981, 1993; Brown & Schultz 1991; Thieret 2003c.