Purple Giant Hyssop (Agastache scrophulariifolia)
Purple giant hyssop grows up to 6 feet tall, forming upright clumps with square stems that may be purplish and lightly hairy. Its flower spikes range from 1 to 6 inches long, bearing numerous ¼-inch tubular flowers in pale purple to lavender hues. Each flower has a two-lobed upper lip and a three-lobed lower lip, with four stamens that extend beyond the corolla. Leaves are opposite, stalked, and sharply pointed—up to 4 inches long and 2 inches wide—with coarsely toothed margins and short hairs on the petioles. This mint-family perennial prefers moist, sandy or loamy soils in dappled shade or woodland edges, thriving in thickets, upland woods, and disturbed floodplain margins. It’s sensitive to competition and benefits from occasional habitat disturbance.