Flora of the Venezuelan Guayana << Back ANNONACEAE 10. HETEROPETALUM Benth., J. Proc. Linn. Soc., Bot. 5: 69. 1860. ---Phaeanthus sect. Heteropetalum (Benth.) Baill., Hist Pl. 1: 245. 1868. by Julian A. Steyermark and Paul E. Berry Trees, the younger stems with simple, appressed hairs, soon glabrescent. Leaves stiff-coriaceous, lanceolate-oblong, long-petiolate. Flowers medium-sized, bisexual, sericeous, axillary, short-pedunculate; pedicels recurved, articulate above the base, the lower articulation with some bracts, the upper naked; receptacle shortly cylindric. Sepals 3, triangular-ovate, valvate, coriaceous; petals 6, usually strongly unequal, coriaceous, the outer ones equaling or somewhat longer than the sepals, the inner ones much longer. Stamens numerous, linear; anthers not locellate, connective strongly truncate-dilated above the anther locules. Carpels numerous, setulose; ovule 1, basal, erect. Monocarps many, free, 1-seeded. Endemic to the Guayana Shield in southeastern Colombia, southern Vene-zuela, and northern Brazil; 1 species. A possibly undescribed species known from a single specimen (Blanco 1256, NY, from Caño Guaco on the middle Río Sipapo, Amazonas state) has large, flattened monocarps and large leaves 12.5--15.5 × 4 cm, but needs flowering material to determine if it is sufficiently distinct from Heteropetalum brasiliense. The wood of this genus is very lightweight and is used for fishing floats and ornamental carvings. Heteropetalum brasiliense Benth., J. Proc. Linn. Soc., Bot. 5: 69. 1860. ---Boya negra, Palo de boya negro. Guatteria heteropetala Benth., London J. Bot. 2: 360. 1843. Heteropetalum spruceanum R.E. Fr., Acta Horti Berg. 10: 75, t. 3. 1931, syn. nov. Heteropetalum spruceanum var. longipet-alum R.E. Fr., Mem. New York Bot. Gard. 9: 330. 1957. Tree 7--15 m; stems shortly appressed-pubescent, soon glabrescent; outer petals 6--20 mm long, inner petals 23--28 mm long. Banks of black-water rivers, 100--200 m; Amazonas (Río Atabapo and tributaries, Río Casiquiare and tributaries, Río Guainía basin, Río Pasimoni, Río Vasiva). Colombia (Guainía), Amazonian Brazil (Amazonas: Rio Negro). Fig. 381. Scientific Comments: Paul Berry (peberry@facstaff.wisc.edu) or Kay Yatskievych (kay.yatskievych@mobot.org).