Long sepal obedient plant (Physostegia longisepala) is a glabrous herbaceous native perennial in the Lamiaceae. The stems are square in cross-section, and the leaves are opposite, simple, mostly sessile, and have pinnate major veins. The large perfect and irregular flowers are opposite in a terminal spike inflorescence. The five sepals become enlarged or inflated in fruit, and the four stamens are exserted. The five petals are two-lipped, with two petals in the upper lip and three in the lower lip and in this species lavender or purple. The four-lobed ovary is superior, and the style arises between the lobes. The fruit is a schizocarp with four mericarps. Very similar to Physostegia intermedia, a plant with smaller flowers. We have longisepala planted on Allen Acres and it is quite happy.