Exostema spinosum (Le Vavass.) Krug & Urb.

Exostema spinosum (Le Vavass.) Krug & Urban; Urban, Ber Deuts. Bot. Ges. 15: 262. 1897.
Cinchona spinosa Le Vavass. Obs. Phys. 37: 243. 1790. Calesbaea Vavassorii Spreng. Syst. 1: 416. 1825. Catesbaea elliptica Spreng.; DC. Prodr. 4: 401, as synonym. 1830. Exostema Vavassorii Griseb. Cat. PI. Cub. 126. 1866.
Shrub, 1-2 meters high, much branched, the branches stout, rigid, grayish, the branchlets
slender, rigid, spinose, minutely puberulent or hirtellous when young; stipules minute, deltoid,
acute, brownish; petioles 1 mm. long or shorter; leafblades oval or oblong, 3-8 mm. long,
1.5-4 mm. wide, rounded or obtuse at the base, broadly rounded at the apex, thick-coriaceous,
lustrous above, the costa evident beneath, the lateral veins obsolete, the margin often sub-
revolute; flowers axillary, solitary, the pedicels very slender, 5-7 mm. long, the bractlets minute; hypanthium oblong, 3-4 mm. long, glabrous; calyx-lobes 4, minute, 0.5 mm. long or
shorter, deltoid, acute; corolla 1.5-2 cm. long, glabrous outside, the 4 lobes linear, 6-9 mm.
long; stamens 4, exserted, the anthers about 4 mm. long; capsule oval-oblong, 8-12 mm. long,
dark-brown, smooth, lustrous.
Type locality: Santo Domingo.
Distribution: Eastern Cuba and Hispaniola.

Exostema spinosum là một loài thực vật có hoa trong họ Thiến thảo. Loài này được (Le Vavass.) Krug & Urb. mô tả khoa học đầu tiên năm 1897.