Stems 2-6 dm, glabrous or nearly so, usually much branched; lvs linear, 1-6 mm wide; pedicels filiform, widely divergent, 1-2 cm at anthesis; cal-tube 2-4 mm, its lobes broadly triangular to subulate, 0.3-2.2 mm; cor 1-1.5 cm, its upper lip arching over the stamens, glabrous within; pollen-sacs 1.5-2.2 mm; 2n=28. Que. to Minn., s. to Fla. and Tex. (A. besseyana)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.