Brunfelsia amazonica is a 1.5 to 2.5 m high shrub or tree whose bark is sand-colored to reddish brown and is interrupted by cracks in the longitudinal direction. The twigs are shiny, hairless and light yellowish-brown.
The leaves are scattered on the branches on 2 to 5 (rarely 8) mm long petioles , which are provided with transverse cracks. The leaf blade is 6.5 to 12 cm long and 2.5 to 5 cm wide. The shape is elongated to lanceolate, often tapering sharply at the tip. The base is broadly wedge-shaped to narrowed. The upper side is dark green, the underside pale green, the entire leaf is hairless and tightly membrane-like. Five to eight (rarely even ten) secondary arteries extend from the midrib.
Inflorescences and flowers
The sessile inflorescences usually consist of one or two flowers , rarely up to five or six. The white or greenish white flowers are fragrant and are each supported by one or two bracts . These are 2 to 6 mm long, linear to lanceolate, hairless and like leaves.
In the flower bud , the flower stalk is initially curved, but later stands upright and becomes 13 to 20 mm long and 1 mm thick. It is slim, slightly thickened towards the tip and hairless. The calyx is 8 to 12 mm long and has a diameter of 5 to 8 mm. It is tubular-bell-shaped, slightly inflated, hairless and membrane-like. The calyx teeth are 2 to 6 mm long, upright, slightly unequal in length, ovate-lanceolate and blunt to tapering to a point.
The corolla tube is 20 to 25 mm long and has a diameter of 1.5 to 3 mm, is about twice as long as the calyx, cylindrical and somewhat narrowed at the transition to the coronary hem, where it is also covered with fine glandular hair. The coronet has a diameter of 15 to 25 mm and is protruding. The corolla lobes are 6 to 11 mm long, elongated to inverted ovoid, somewhat convex, blunt or round at the tip, the sides are slightly bent during flowering. The crown lobes are slightly different in size or the crown lobe on top is slightly larger.
The four stamens are attached in the middle of the corolla tube and do not protrude beyond it. The stamens are almost tongue-shaped, the upper pair is 5 mm long, the lower only 2 to 3 mm. The anthers have a diameter of 1 to 1.5 mm and are circular-kidney-shaped.
Fruits and seeds
The spherical fruit is about 10 mm long, pointed, green and has a soft, thin pericarp about 0.2 mm thick. When ripe, the fruit dries up and hardly cracks open. The eight to ten seeds are 5 to 6 mm long and 3 mm in diameter, they are elongated-kidney-shaped, flattened on one or two sides and angled. The surface is dark brown and granular, the hilum sits in the middle. The embryo is about 3 mm long, slightly curved, the elliptical cotyledons are 0.5 mm long.
The species was found in bloom between January and May; ripe fruits were only found in May.
- Timothy C. Plowman (Author), Sandra Knapp, JR Press (Ed.): A Revision of the South American Species of Brunfelsia (Solanaceae) . Field Museum of Natural History, Chicago August 1998, ISBN 978-9998104693 . (Fieldiana Botany, New Series, number 39).