Cardinal penstemons are perennial plants that grow flowering stems that are tall. A plant can have just a few or several stems that are hairless and slightly
glaucous. The leaves are also hairless, but are not glaucous, with the lowest ones on the stems and the
basal leaves measuring long and wide. The stems have three to seven pairs of leaves attached to opposite sides. Flowering for variety
cardinalis in New Mexico is in June or July, while variety
regalis typically blooms in May or June, but occasionally as late as August in its native habitat. The flowers are dark red to blue-red tubes that are slightly swollen with a smaller mouth. The flowers measure 22–30 mm and are only weakly two lipped. Its fruits are
capsules that measure 10–15 millimeters long and 5–9 mm wide. ==Taxonomy==