Buddleja davidii
Nouv. Arch. Mus. Hist. Nat., sér. 2, 10: 65. 1887–1888.
Shrubs, 5–30 dm. Stems branched, tomentose. Leaves often with auriculate stipules; petiole 5 mm; blade ovate to ovate-lanceolate, 10–15 × 2–4 cm, base attenuate or cuneate, margins serrate or subentire, apex acute or acuminate, abaxial surface tomentose, adaxial glabrous or glabrescent. Inflorescences terminal, tapered-spicate or narrowly paniculate thyrses, 10–20 × 2–4 cm, cymes almost encircling inflorescence axis, 10–25 pairs, 3–30-flowered. Pedicels essentially absent; bracteoles present. Flowers fragrant; calyx sparsely hairy externally, tube 1.5–2 mm, lobes 0.5–1.5 mm; corolla straight, violet or pink, rarely white, often with yellow-orange eye, salverform, tube 8–10 mm, lobes suborbiculate, 2–3 × 2–3 mm; stamens inserted medially in corolla tube, included in tube; ovary ovoid, 2 mm, glabrous or puberulent; stigma clavate, 1 mm. Fruits capsules, brown, narrowly ellipsoid, 5–9 × 1.5–2 mm, glabrous or puberulent, dehiscence primarily septicidal. Seeds threadlike, 3–4 × 0.5 mm, wings long. 2n = 76.
Phenology: Flowering May–Oct; fruiting Jul–Nov.
Habitat: Roadsides, railroad embankments, quarries, streambeds, landslide scars, sandy lakeshores, disturbed sites.
Elevation: 0–1300 m.
Distribution
B.C., Ont., Ala., Calif., Conn., Del., D.C., Ga., Ill., Ky., Md., Mass., Mich., Mo., N.J., N.Y., N.C., Ohio, Oreg., Pa., R.I., S.C., Tenn., Va., Wash., W.Va., Asia (China), introduced also in Central America, South America, Europe, Africa, Pacific Islands (Hawaii, New Caledonia, New Zealand), Australia.
Discussion
Buddleja davidii has been designated as a noxious weed in Oregon and Washington; it is a serious invader also in England, New Zealand, and Australia. It can often form dense thickets and produce abundant seeds (N. G. Tallent-Halsell and M. S. Watt 2009).