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sixweeks three-awn, three awn

pineland threeawn, wiregrass

Habit Plants short- to long-lived annuals. Plants perennial; cespitose, occasionally with rhizomes.
Culms

(3)10-50(80) cm, often highly branched above the base.

60-120 cm, stiffly erect, unbranched.

Leaves

cauline, glabrous;

sheaths shorter than the internodes, not disintegrating into threadlike fibers;

ligules 0.4-1 mm;

blades 2-14 cm long, 1-2.5 mm wide, flat to involute.

basal or nearly basal;

sheaths shorter than the internodes, smooth and mostly glabrous abaxially, sometimes with a line of widely spaced, 0.5-1 mm hairs over the midvein, not disintegrating into threadlike fibers at maturity;

collars glabrous, sometimes with a few conspicuous hairs at the sides;

ligules 0.1-0.3 mm;

blades 15-50 cm long, 0.3-1 mm wide, tightly involute, stiff, yellow-green, abaxial surfaces villous on both sides of the midvein, at least on the basal portion, hairs 0.6-1.5 mm, adaxial surfaces densely scabrous or densely short pubescent.

Inflorescences

panicles, 5-15(20) cm long, 0.5-3 cm wide, often interrupted below;

nodes glabrous or with straight, less than 0.5 mm hairs;

primary branches 1-4 cm, erect to ascending, without axillary pulvini, with 3-8 spikelets.

paniculate, 20-35 cm, 5-8 mm wide;

nodes glabrous;

primary branches 2-5 cm, appressed, without axillary pulvini, with 4-12 spikelets, spikelet-bearing to the base.

Spikelets

crowded.

appressed.

Glumes

unequal, 1-veined, acuminate;

lower glumes 4-8 mm;

upper glumes 6-11 mm;

calluses 0.5-0.8 mm;

lemmas 6-9 mm, slightly keeled, midveins scabrous, junction with the awns not evident;

awns not disarticulating at maturity, flattened and straight to somewhat curved at the base, central rib flanked by equally wide pale wings;

central awns 7-15(20) mm;

lateral awns somewhat shorter, occasionally only 1-2 mm;

anthers 3, 0.3-0.7 mm.

subequal, glabrous, light brown or tan, usually 1(2)-veined, bifid and awned, awns 1.5-2.5 mm;

lower glumes 7-10 mm;

upper glumes 6-9 mm;

calluses 0.4-0.6 mm;

lemmas 6-9 mm, glabrous, light-colored when young, reddish when mature, column 1-2 mm, not twisted, junction with the awns inconspicuous;

awns (7)10-15(22) mm, subequal, usually horizontally spreading or curving downward, not disarticulating at maturity;

anthers 3, about 3 mm, reddish-brown.

Caryopses

4-5 mm, chestnut brown.

2n

= 22.

= unknown.

Aristida adscensionis

Aristida stricta

Distribution
from FNA
AZ; CA; CO; KS; MD; MO; NE; NM; NV; NY; OK; SC; TX; UT; HI; PR; Virgin Islands
[WildflowerSearch map]
[BONAP county map]
from FNA
NC; SC
[WildflowerSearch map]
[BONAP county map]
Discussion

Aristida adscensionis grows in waste ground, along roadsides, and on degraded rangelands and dry hillsides, often in sandy soils. It is associated with woodland, prairie, and desert shrub communities. Its range extends from the United States south through Mexico and Central America to South America.

Because Aristida adscensionis is highly variable in height, panicle size, and awn development, several varieties have been described. None are recognized here because most of the variation appears to be environmentally induced.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Aristida stricta grows in pine barrens and sandy fields of the coastal plain from Louisiana to North Carolina. Peet (1993) segregated northern populations of A. stricta as a separate species, A. beyrichiana Trin. & Rupr., based on pubescence patterns of the sheath and blades. Investigations into alloyzyme diversity (Walters et al. 1994), anatomy, morphology, and phenotypic expression (garden transplants) led Kesler (2000) to conclude that such a segregation was not justified; pubescence patterns particularly were inconclusive. Consequently, A. beyrichiana is treated here as part of A. stricta.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 25, p. 330. FNA vol. 25, p. 335.
Parent taxa Poaceae > subfam. Aristidoideae > tribe Aristideae > Aristida Poaceae > subfam. Aristidoideae > tribe Aristideae > Aristida
Sibling taxa
A. arizonica, A. basiramea, A. californica, A. condensata, A. desmantha, A. dichotoma, A. divaricata, A. floridana, A. gypsophila, A. gyrans, A. havardii, A. lanosa, A. longespica, A. mohrii, A. oligantha, A. palustris, A. pansa, A. patula, A. purpurascens, A. purpurea, A. ramosissima, A. rhizomophora, A. schiedeana, A. simpliciflora, A. spiciformis, A. stricta, A. ternipes, A. tuberculosa
A. adscensionis, A. arizonica, A. basiramea, A. californica, A. condensata, A. desmantha, A. dichotoma, A. divaricata, A. floridana, A. gypsophila, A. gyrans, A. havardii, A. lanosa, A. longespica, A. mohrii, A. oligantha, A. palustris, A. pansa, A. patula, A. purpurascens, A. purpurea, A. ramosissima, A. rhizomophora, A. schiedeana, A. simpliciflora, A. spiciformis, A. ternipes, A. tuberculosa
Synonyms A. interrupta, A. bromoides, A. adscensionis var. modesta A. beyrichiana
Name authority L. Michx.
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