Uvariastrum Engl., Monogr. Afrik. Pflanzen.-Fam. 6: 31. 1901.

Couvreur, Thomas L. P., 2014, Revision of the African genus Uvariastrum (Annonaceae), PhytoKeys 33, pp. 1-40 : 6

Uvariastrum Engl., Monogr. Afrik. Pflanzen.-Fam. 6: 31. 1901.

Type species.

Uvariastrum pierreanum Engl. & Diels

Description.

Trees or shrubs, up to 30 m tall, 15-45 cm in diameter. Trunk straight, sometimes fluted, cylindrical. Phyllotaxis distichous. Petioles 1-7 mm long, glabrous or densely pubescent. Leaves simple, entire, petiolate and exstipulate, 6-22 cm long, 2-5 cm wide, narrowly elliptic to obovate, glabrous to pubescent. Midrib impressed on the upper side, raised on the lower side; secondary venation brochidodromous, impressed or flat on upper side, tertiary venation reticulate. Inflorescence 1-3 flowered, on young or old branches, sometimes cauliflous then with numerous flowers (more than 10). Bracts, 1-3, semi-amplectent, basal, caducous. Sepals 3, free, reduplicate-valvate, enclosing the receptacle until anthesis, 0.7-2.5 cm long, 0.5-1.8 cm wide, very broadly ovate to ovate, pubescent to glabrous on outer side, pubescent on inner side. Petals in two whorls of three each, valvate, free, subequal to outer longer than inner, outer petals 1-3.5 cm long, 0.5-1.5 cm wide, elliptic to ovate, pubescent; inner petals 1-2.8 cm long, 0.5-1.5 cm wide, elliptic to ovate, pubescent. Receptacle pyramidal to convex with a flat apex. Stamens numerous, spirally arranged, 2-6 mm long, extorse, basifixed, filament short and wide, connective present, discoid or tongue-shaped, glabrous to pubescent. Pollen grains as tetrads, inaperturate. Carpels (1)5-15, 2-6 mm long, densely pubescent, style absent, stigma capitate, Ovules numerous, lateral, biseriate, placentation parietal. Monocarps 1-8, 2.5-10 cm long, 1-5 cm in diameter, ellipsoid, oblong to globose, pubescent to glabrous, longitudinally ribbed to smooth, constricted or not around the seeds, shortly stipitate to sessile, stipe 1-9 mm long. Seeds 3-27 to numerous, 0.7-2.5 cm long, 0.7-1.5 cm wide, flat to transversely ellipsoid, raphe raised to flat.