False Dragonhead (Obedient Plant)
Native perennial with single or sparingly branched, hairless stems that are square in cross-section. Flowers in long, terminal and a few lateral spikes, tightly spaced in vertical rows, pink to pale lilac with darker purplish markings, funnel-shaped with a hoodlike upper lip and a 3-divided lower lip, lacking scent. Blooms May–September. Leaves opposite, stalkless, narrowly lance-shaped, sharply toothed, to 5 inches long.
Similar species: Two other "false dragonheads" occur in Missouri, both with more limited ranges. P. angustifolia has less-dense flowering spikes and thicker, narrower leaves; it occurs only in the southern half of the state. P. intermedia has smaller flowers and few or no teeth on the leaves; it is limited to swampy areas of our southwestern counties.