Hexalobus crispiflorus is a species of plant in the family Annonaceae. It is native to Angola, Benin, Cameroon, Central African Republic, Congo, DR Congo, Gabon, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Nigeria, Senegal, Sierra Leone, Sudan, Togo and Zaire. Achille Richard, the French botanist who first formally described the species, named it after its wavy ( in Latin) petals of its flowers.
It is a tree reaching in height. Its trunk has deep vertical channels. Its brown to rust-colored bark has vertical cracks and peels off in long narrow strips. Its small branches are covered in dense hairs. Its petioles are 2âÂÂ8 by 1âÂÂ2.5 millimeters and covered in dense light-colored to brown hairs. Its elliptical to lance-shaped, leathery leaves are 7.2-25 by 2.5-8.5 centimeters with tapering tips that end in a blunt point and bases that are varyingly heat-shaped, rounded or wedge-shaped. The upper surfaces of the leaves are glossy, grey, hairless and sometimes have a puckered appearance from their venation. The undersides of the leaves are covered in sparse brown hairs that are 0.3 millimeters long. The leaves have 9âÂÂ19 pairs of secondary veins emanating from their midribs at angles of 42ð-75ð. Its fragrant, bisexual flowers occur in groups of 1âÂÂ3 on peduncles that are 2âÂÂ13 by 1-2 millimeters. The flowers are attached to the peduncles by pedicels that are 4âÂÂ17 by 1.2-3 millimeters. The peduncle has 5âÂÂ6 bracts that are 8âÂÂ12 by 4-9 millimeters. The top two bracts are fused at their base to form a tube that is 4 millimeters long. The peduncle and pedicles are covered in dense golden to rusty hairs. Its 3 sepals are 12âÂÂ21 by 5.5-16 millimeters and bent backwards at maturity. The outer surfaces of sepals are densely covered in 0.1-millimeter-long rust-colored hairs interspersed with longer hairs up to 2 millimeters. The insides of the sepals are densely covered in curly hairs. Its flowers have 6 petals that are fused at the base to form a 6-lobed corolla that is yellow with a purple base. The basal tubes of the corollas are 4-10 millimeters long. The lance-shaped lobes are 37âÂÂ80 by 6-21 millimeters with rounded tips. The corollas are covered with light-colored to brown hairs except on the basal internal surfaces which are sometimes hairless. The margins of the lobes of the corolla are wavy. Its flowers have numerous oblong stamen that are 3âÂÂ5.1 by 0.5-0.8 millimeters.
The connective tissue between the lobes of the anther extends upward to form a rounded cap. Its flowers have 7âÂÂ16 densely hairy carpels. Its stigma are positioned horizontally on the ovaries and are 2.1-3.5 by 1.1-3.1 millimeters. The smooth, oblong to elliptical fruit occur in groups of 1-8 and are 4.2-9.5 by 3.5-6.5 centimeters. The fruit range from hairless to densely covered in velvety rust-colored hairs that are 0.1 millimeters long. The fruit have 12-36 brown, flattened, elliptical, convex seeds that are 2.8-4 by 1.7-2 by 0.5-0.9 centimeters.
The pollen of H. bussei is shed as permanent tetrads.
It has been observed growing in tropical rainforests and woodland savannas at elevations of .
Bioactive molecules extracted from its bark have been reported to have antiplasmodial activity in tests with Plasmodium falciparum.