[3] The generic name Trompettia is derived from the French 'trompette', diminutive of 'trompe' (horn) and alludes to the shape of the flowers, which resemble small trumpets.

Leaves borne in clusters on very short shoots (these < 1 mm long), subtended by dense protrusions of trichomes, on short petioles to 5 mm long, these pubescent with short eglandular trichomes or glabrous, the blades simple, alternate, narrowly obelliptic to narrowly elliptic, 20-50 × 3–10 mm, (2-)4.7 to 7.5 times longer than wide, the bases attenuate, the apices broadly acute to obtuse, the margins entire, both surfaces covered by glandular trichomes (these seeming to result in black spots on pressed specimens) with occasional sparse simple trichomes along midrib of abaxial surface.

Flowers solitary in leaf axils, on pedicels to 6 mm long, pubescent with eglandular trichomes, pendant.

Ovary superior, bilocular, surrounded by dark red nectary at base, glabrous, the styles 27–29 mm, included within the corolla.

Trompettia cardenasiana is similar to Brugmansia species in bearing both pendant flowers and fleshy, indehiscent fruits.