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

830 POACEAE/ARISTIDA
(Turner et al. 2003) in the Gulf Prairies and Marshes; se Canada (s Ont.) and widespread in the e
1/2 of the U.S. Aug–Nov.
Aristida lanosa Muhl. ex Elliott, (woolly), WOOLLY-SHEATH THREEAWN, WOOLLY TRIPLEAWN
GRASS, WOOLLY THREEAWN. Perennial to ca. 1.2(–1.5) m tall; leaf sheaths (at least lower ones)
lanate, the hairs cobwebby, kinked, and intertwined; panicles with appressed or somewhat
spreading branches, the nodes lanate; glumes subequal, 9–15(–18) mm long including the awn
when present; lemma (6.5–)8–9(–10) mm long, without a well-defined awn column; lemma
awns only curved below, the central awn 12–28(–32) mm long, the lateral awns 7–17 mm long.
Openings in woods, often in sandy soils; widespread in Pineywoods and Post Oak Savannah w
to Montague (BRIT) (in Cross Timbers and Prairies) and Bastrop (Turner et al. 2003) cos.; se U.S.
from NJ s to FL w to MO, OK, and TX. Late Aug–Nov. This species is similar in appearance to A.
desmantha, which also has lanate leaf sheaths. However, A. desmantha has lemma awns with a
semicircular bend and a distinct awn column well-differentiated from the lemma. Wipff
(2003f) indicated that A. lanosa “is sometimes confused with A. palustris, but differs in several
reproductive, vegetative, and habitat characteristics”—e.g., A. palustris has glabrous leaf sheaths
and glabrous inflorescence nodes and typically occurs in bogs or other moist to wet areas.
Aristida longespica Poir., (long-spiked), SLIM-SPIKE THREEAWN, RED THREEAWN. Annual; culms
slender, often geniculate (= bent abruptly) at base, to 65 cm long; leaves not in a conspicuous
basal tuft; panicles contracted, narrow and spike-like; glumes about equal, (3–)4–9(–11) mm
long; central lemma awn erect to reflexed. Two varieties, not always easily distinguished, occur
in East TX; Allred (1986) noted that intermediates between the 2 are not uncommon, but since
the extremes are so strikingly different, distinction at the varietal level seems appropriate.
Sandy open areas. Late Aug–Dec.
1. Lemma usually (3.5–)7–10 mm long; central lemma awn usually (8–)12–27(–36) mm long; lateral
awns usually 2/3–3/4 as long as central, usually 6–18 mm long __________________________ var. geniculata
1. Lemma usually 2.5–7 mm long; central lemma awn usually (1–)5–10(–15) mm long; lateral awns
much shorter, usually 1/3–slightly more than 1/2 as long as central, usually (0–)2–5(–8) mm long
____________________________________________________________________________ var. longespica
var. geniculata (Raf.) Fernald, (jointed), KEARNEY’S THREEAWN, PLAINS THREEAWN. Widespread in
e 1/2 of TX; se Canada (Ont.) and e 1/2 U.S. from NH to FL w to SD and TX. Aug–Dec. [A.
intermedia Scribn. & C.R. Ball]
var. longespica. SLIM-SPIKE THREEAWN, SLENDER THREEAWN. Pineywoods and Gulf Prairies and
Marshes w to West Cross Timbers; se Canada (Ont.) and e 1/2 U.S. from NY to FL w to MN and
TX, also AZ and WA.
Aristida oligantha Michx., (few-flowered), OLDFIELD THREEAWN, PRAIRIE THREEAWN, FEW-
FLOWER ARISTIDA. Annual; inflorescence few-flowered, spicate or less often paniculate; glumes
subequal, 18–25 mm long, the second with an awn to 1 cm long; lemma usually 16–28 mm long,
the awns about equal, usually 3–7 cm long. Calcareous or sandy soils, fields, wasteplaces, and
roadsides; widespread in e 1/2 of TX; Hatch (2002) cited all 10 vegetational areas; widespread in
e 1/2 of U.S., scattered in w U.S. and s Canada. Jun–Nov. This species apparently has allelopathic
effects on other plants. It is also often seen growing on seed harvester ant mounds (J. Stanford,
pers. comm.).
Aristida palustris (Chapm.) Vasey., (marsh-loving), LONG-LEAF THREEAWN. Tufted perennial
similar to A. lanosa but with glabrous leaf sheaths; culms 0.75–1.5 m tall; panicles narrow;
glumes (7.5–)9–13.5 mm long, slightly unequal, the second very slightly longer than the first,
the awns only 1–2 mm long; lemma 6–9.2 mm long, the awns unequal, the central awn 1.5–4 cm
long, the lateral awns (0.8–)1–3.5 cm long. Margins of marshes, seeps, bogs, and other moist to
wet areas; the only East TX records known to us are from Hardin (McRoberts & McRoberts 3664,