Named for Armand David, the Catholic missionary-naturalist who sent hundreds of specimens from China to European herbaria in the 19th century, Buddleja davidii arrived in Western gardens and immediately made itself at home — perhaps too thoroughly. Native to Tibet and central and south China, it grows 6 to 12 feet high and up to 15 feet wide, with arching stems, grayish-green to dark green ovate-lanceolate leaves, and terminal spikes of lilac-colored blooms with a characteristic orange throat measuring 4 to 10 inches long. Flowering on new wood means it can be cut hard in early spring and still bloom abundantly by midsummer. Its tolerance for deer, drought, heat, humidity, and salt gave it early and persistent popularity.

The ecological complexity is real and worth knowing. A single panicle can carry as many as 40,000 seeds — lightweight, winged, viable for three to five years in the soil — and even cut stems can re-sprout. It is listed as invasive in Redwood National Park, labelled a noxious weed in Oregon and Washington, and flagged as a severe threat by the North Carolina Native Plant Society. Crucially, while adult butterflies can feed on its nectar, native butterfly larvae cannot eat its leaves, meaning it draws pollinators without supporting them through their full lifecycle. The sterile cultivars developed through NC State's Lo & Behold® program offer much of the garden appeal with a fraction of the ecological footprint, and in most situations represent the more considered choice.