Roundstem foxglove is an erect forb, 10-60cm tall. Its flowers are pink, bell-shaped, with 3 lower lobes, and almost always appear on the tips of the branches. The lobe surfaces are softly hairy and with small hairs on outside. Corollas have 2 yellow lines and many red spots inside the throats. Fruit is rounded, 4-5mm in diameter with yellow-brown seeds that have a netted texture on the surface. The pedicels of flowers and fruits in upper axils are 1.5-4 times as long as subtending bracts, ridged, but lacking fibers in the ridges. Its leaves are numerous, opposite, slender, and 1.0-3.4cm long.
2024: Differs from A skinneriana in having many spreading/weakly ascending branches (some with secondary branching) and stems not strongly winged. Differs from A tenuifolia (which rare will occur in dry situations) by having bracts/leaves subtending flowers that are much shorter than flower stalks. Differs from A aspera, which also occurs on this site by being shorter, less robust, with a much shorter calyx and much smaller fruit (~4mm vs. about double that or larger). Roundstem foxglove can be distinguished from other Agalinis species by its habitat and leaf width (up to 1mm). Rough false foxglove (A aspera) is found in dry sites but has rough stems and turns black when dried whereas roundstem false foxglove has glabrous stems and remains green upon drying.
