Nov. Gen. Sp. 2(fol.): 278; 2(qto.): 345; plate 182. 1818.
Shrubs or trees, 15–40 dm. Stems much-branched, tomentose when young. Leaves: basal: stipular lines evident; petiole 10–40 mm; blade ovate, 9–23 × 5–14 cm, base attenuate to obtuse, decurrent, margins serrate or double-serrate, apex acute or acuminate, abaxial surface tomentulose, adaxial glabrate; cauline: stipular lines evident; petiole 0–10 mm; blade lanceolate or narrowly elliptic, 5–15 × 1.5–3 cm, base attenuate, decurrent, margins entire or irregularly serrate, apex acute, abaxial surface tomentulose, adaxial glabrate. Inflorescences terminal, pseudoverticillate spikes, 6–25 × 1–3 cm, cymes 5–20 pairs, 10–35-flowered. Pedicels absent; bracteoles absent. Flowers malodorous; calyx tomentose externally, tube 1.7–3 mm, lobes 1–1.8 mm; corolla yellow, funnelform, tube 3.2–4.2 mm, lobes ovate, 1–1.5 × 1.2–1.7 mm; stamens inserted 1 mm proximal to orifice of corolla-tube, included in tube; ovary ovoid, 1–1.5 mm, distal 1/2 tomentose; stigma clavate, 1.2–1.4 mm. Fruits capsules, brown, cylindric, 4–4.5 × 1.7–2 mm, tomentose at apex, dehiscence septicidal and loculicidal. Seeds fusiform, 0.8–1.2 × 0.3–0.4 mm, wings short. 2n = 76.
Phenology: Flowering Jan–Apr; fruiting Mar–Jun.
Habitat: Tamaulipan thorn scrub, riparian woodlands, roadsides.
Elevation: 10–1400 m.
Ariz., Tex., Mexico
Buddleja sessiliflora is found in association with Dodonaea viscosa, Fouquieria splendens, and Parkinsonia aculeata in Arizona and with Celtis laevigata, Fraxinus berlandieriana, and Prosopis glandulosa in southernmost Texas. It is widespread in Mexico from Sonora and Tamaulipas to the Isthmus de Tehuantepec, except in the Chihuahuan Desert, at elevations to 2800 m.