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10. HETEROPETALUM Benth., J. Proc. Linn. Soc., Bot. 5: 69. 1860. ---Phaeanthus sect. Heteropetalum (Benth.) Baill., Hist Pl. 1: 245. 1868.
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.
11. OXANDRA A. Rich. in Sagra, Hist. Phys. Cuba, Bot. Pl. Vasc. 10: 45. 1845.
Trees or shrubs. Flowers small, axillary, solitary or in few-flowered inflorescences; receptacle hemispheric; pedicels slightly articulate above the base, bearing several small, distichous bracts below the articulation and one above it. Sepals 3, connate at the base, imbricate in bud; petals 6, subequal, rounded, ovate, or oblong, thin, biserially imbricate, the margins often ciliate. Stamens 6--20, flattened; anthers linear, locules not locellate, the connective elongated above the anther locules into a triangular or lanceolate appendage. Carpels few, (1--)4--13; ovule 1, basal, erect. Monocarps shortly stipitate or subsessile, 1-seeded.
Mexico, Guatemala, Panama, West Indies, Colombia, Venezuela, Guyana, Suriname, French Guiana, Ecuador, Peru, Brazil, Bolivia; 24 species, 7 in Venezuela, 6 of these in the flora area.
1. Base of leaf blades truncate with a laterally directed tooth-like process on each side...O. xylopioides
1. Base of leaf blades acute, obtuse, or slightly rounded, without any tooth-like process...2
2(1). Leaf blades with a distinct marginal vein 3--5 mm from the margin, sec-ondary veins strongly impressed...O. euneura
2. Leaf blades without a distinct marginal vein, secondary veins not impressed...3
3(2). Midrib of upper leaf surface flat
3. Midrib of upper leaf surface distinctly raised...5
4(3). Twigs glabrous; leaves acute to shortly and broadly acuminate at the apex; pedicels 1--2 mm long...O. espintana
4. Twigs covered with erect hairs; leaves long-acuminate at the apex; pedi-cels 3--4 mm long...O. sp. A
5(3). Twigs whitish, glabrous; inflorescence several-flowered; pedicels 5--10 mm long...O. leucodermis
5. Twigs never whitish (brown to black), commonly with brownish hairs when young; inflorescence 1-flowered; pedicels 1--3 mm long...O. asbeckii
Oxandra asbeckii (Pulle) R.E. Fr., Acta Horti Berg. 10: 167. fig. 5a & b. 1931. ---Bocagea asbeckii Pulle, Recueil Trav. Bot. Nierl. 6: 262. 1909.
Shrub or tree 4--15 m; leaves glabrous, shiny on upper surface, lanceolate or elliptic-lanceolate, 7--13 W 2.5--4.5 cm; monocarps ellipsoid, shortly apiculate, 1.5--2 cm long. Evergreen lowland forests, ca. 100 m; Amazonas (Isla del Araguato near Isla Ratsn). Guyana, Suriname, French Guiana.
Oxandra espintana (Spruce ex Benth.) Baill., Hist. Pl. 1: 207. 1868. ---Bocagea espintana Spruce ex Benth., J. Proc. Linn. Soc., Bot. 5: 71. 1860.
Shrub or tree 5--10 m; leaves ovate- or oblong-elliptic, 6--11 W 2--5 cm; monocarps obovoid or ovoid, rounded at apex, ca. 1 cm long. Riparian evergreen forests, ca. 100 m; Bolmvar (middle Rmo Orinoco), Amazonas (Isla Ratsn). Zulia; Colombia, Peru, Brazil, Bolivia. Fig. 382.
Oxandra euneura Diels, Notizbl. Bot. Gart. Berlin-Dahlem 10: 173. 1927.
Tree 2--8 m; leaves 13--20 W 5--7 cm, narrowly elliptic, apex distinctly acuminate; monocarps ellipsoid, strongly narrowed towards the apex, 20--25 W 8--10 mm. Evergreen lowland forests, 100--200 m; Amazonas (Piedra Cocuy). Common in Amazonian Colombia, Peru, and Brazil.
Oxandra leucodermis (Spruce ex Benth.) Warm., Vidensk. Meddel. Dansk Naturhist. Foren. Kjxbenhavn. 1873: 147. 1873. ---Bocagea leucodermis Spruce ex Benth., J. Proc. Linn. Soc., Bot. 5: 71. 1860.
Tree 6--10 m; twigs whitish; leaves oblong-elliptic, 8--17 W 2.5--5 cm; flowers solitary or few on leafless portions of the older stems, pedicels curved; monocarps rounded at apex. Seasonally flooded evergreen lowland forests, ca. 100 m; Amazonas (Rmo Casiquiare, Rmo Negro). Endemic.
Oxandra xylopioides Diels, Notizbl. Bot. Gart. Berlin-Dahlem 10: 172. 1927.
Tree 3--25 m; leaves linear-oblong, 1.5--2 cm wide; flowers small, cream-colored. Evergreen lowland forests, ca. 100--200 m; Amazonas (Rmo Mawarinuma). Amazonian Colombia, Guyana, French Guiana, Ecuador, Peru, Brazil.
Oxandra sp. A. ---Majagua.
Tree 5--6 m; young branches rather densely covered with erect hairs; leaves narrowly ovate, apex long-acuminate, 6--10 W 2--3.5 cm, base obtuse to slightly cordate, both sides reticulate; monocarps subglobose, 8--10 mm diameter. Seasonally flooded forests, ca. 100 m; Amazonas (El Bagre near Puerto Ayacucho).
