This biennial is closely related to angularis, but more concentrated on the southeastern Coastal Plain, especially on acid sandy soils (Cr, W). It has narrower leaves (L/W ca. 2.5-4 versus 1.5-3), broadest near the middle above the tapered base (versus near the rounded-subcordate base); also, stems are not winged below the middle (versus winged); flowers tend to be smaller and less numerous; 2n = 32 versus 38. A patch of about 30 plants was discovered in 1994 by J. Kiser (KY), on a roadside by the large powerline on uplands at Duck Run in se. MCRE. Some plants had white flowers. These have not reappeared in recent years; fire or soil disturbance is probably required to allow fresh establishment, but mowing has been excessive. S. brachiata may also be expected in TRIG, since it is locally frequent on Fort Campbell in adjacent Montgomery Co., Tenn. (D. Estes, pers. comm.).