Aristida stricta
Aristida havardii
pineland threeawn, wiregrass
harvard threeawn, Havard threeawn, Havard's threeawn
60-120 cm, stiffly erect, unbranched.
15-40 cm, slender, usually erect, occasionally decumbent, often tightly clustered into hemispheric clumps, unbranched.
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.
mostly basal;
sheaths longer than the internodes, glabrous except at the summit;
collars densely pilose;
ligules 0.5-1 mm;
blades 5-20 cm long, 1-2 mm wide, flat to loosely involute, glabrous.
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.
paniculate, 8-18 cm long, 4-12 cm wide, peduncles often flattened and easily broken;
rachis nodes glabrous or with straight, less than 0.3 mm hairs;
primary branches 2-6 cm, stiffly divaricate to reflexed, with axillary pulvini, usually naked on the lower 1/2 secondary branches usually absent.
appressed.
usually divergent, pedicels usually with axillary pulvini.
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.
8-12 mm, 1-veined, acuminate or awned, awns to 4 mm;
calluses about 0.5 mm;
lemmas 8-13 mm long, glabrous, smooth or scabrous, terminal 2-3 mm straight or with 1-2 twists, narrowing to 0.1-0.2 mm wide, junction with the awns not evident;
awns (7)10-22 mm, not disarticulating at maturity, from almost straight to somewhat curved basally, ascending to divergent distally;
lateral awns slightly shorter and thinner than the central awns;
anthers 3, 0.8-1 mm.
4-5 mm, chestnut brown.
8-10 mm, light brown.
= unknown.
= 22.
Aristida stricta
Aristida havardii
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.)
Aristida havardii grows on dry hills and plains in desert grassland to pinyon-juniper zones, and in sandy to rocky ground from the southwestern United States to northern Mexico. It occasionally intergrades with A. divaricata, but that species differs in having more twisted lemma beaks, longer primary branches, well-developed secondary branches, and, usually, appressed spikelets.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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