glabrate

Perennial, branching, puberulent or glabrate, low; leaves narrow, pinnately or bipinnately parted, the lobes and teeth bristle-tipped; heads small, the appressed scales bristle-tipped; achenes pubescent.—Minn. to Kan., and southward.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray

Stem 2–5° high; leaves linear or linear-lanceolate, entire, usually glabrate above; heads oblong, canescent, 2–3´´ long—Minn. to Neb., and westward.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray

Leaves crowded, thick, often coarsely toothed, sparingly villous-tomentose; peduncles very short; tails villous or glabrate, not plumose.—Mo. and Kan. § 3.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray

Pubescent or glabrate; stem slender, simple, with few large heads terminating slender branchlets; leaves lanceolate, very acute, narrowed to a sessile base, sparingly serrate or serrulate; scales linear-attenuate, equal, mostly herbaceous; rays blue.—N. Dak. and westward.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray

More slender, glabrate, naked above; scales obovate-oblong, petaloid at apex.—Neb. to Ark. and Tex.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray