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.
This species is probably found throughout the state although it may not be present in the dune area. Infrequent in the northern counties and frequent in the southern counties. With the exception of an intermediate form all of my specimens were found on white and black and white oak slopes and on chestnut oak ridges. The extreme variability of this species has led authors to divide it into species and varieties. The well known botanist, E. L. Greene, found a very wide leaf form near Ridgeville, Indiana, which he described as a new species. The forms seem to intergrade and are so perplexing that I have copied the section of Pennell's key to this species and its varieties and I have indicated my specimens on the maps as he has named them.
Indiana Coefficient of Conservatism: C = 4
Wetland Indicator Status: FACW
Diagnostic Traits: Leaves opposite, linear, deep-green; pedicels longer than the calyx; calyx weakly veined. Multiple varieties (which see).