Plant Family: Belongs to the Verbenaceae family, which includes Teak (Tectona grandis) and Bois Lezard (Vitex divaricata).

Description: A climbing or free-standing woody shrub; free standing specimen located in lawn near office of Agriculture Division; these can achieve heights of up to 4 m (13 ft); more often rambles up trellises, fences, walls and other support, climbing to as much as 12 m (40 ft); leaves elliptical, apex and base rounded,12-20 cm long (5-8 in.) and 6-10 cm wide (2.5-4 in), opposite, leathery, grayish-green and rough, hence one common name: Sandpaper Vine; flowers bluish-purple, 3-5 cm in diameter (1-2 in.), in very showy terminal raceme inflorescences, hanging 18-26 cm long (7-10 in); calyx deeply 5-lobed; petaloid lavender sepals persist after darker purple or blue petals fall, older flowers finally turning tan; when in full bloom tree almost covered with flowers; small fruit enclosed in persistent sepals which form the wings of the mature seeds; there is also a white variety.

Natural Habitat: Moderate rainfall to humid areas of the east coast of the Eastern Caribbean islands, but hardy and drought resistant; occasional vine found in forests of Dominica; propagation from stem cuttings, layering and seed.

Origin and Distribution: Native to the Lesser Antilles of the West Indies; today widely grown throughout Caribbean, and variously in the tropics and subtropics; cultivated as landscape specimen in Dominican homes, especially on the Atlantic coast.

Uses: Beautiful cultivated ornamental when in full bloom, with striking bunches of bluish purple flowers.

Indigenous Legends: Reportedly, Caribs use flowers mixed with those of the Agouti Vine (Chiococca alba) in an abortion tea; similarly, Petrea flowers mixed with those of Tannia (Xanthosoma sp.), Couroupoume (Myrcia citrifolia) and Goatweed (Capraria biflora) are boiled in tea for diarrhoea.

References:
Gerald Carr. Flowering Plant Families. Univ. of Hawaii, Honolulu, Hawaii, 2004 (botany.hawaii.edu)
C.D. Adams. Flowering Plants of Jamaica. University of the West Indies, Mona, Glasgow University Press 1972
Dorothy P. Storer. Familiar Trees and Cultivated Plants of Jamaica. Macmillan, London 1964
G.W. Lennox and S.A. Seddon. Flowers of the Caribbean. Macmillan, London 1978
H.F. Macmillan. Tropical Planting and Gardening. Macmillan, London 1956
Dan H. Nicolson. Flora of Dominica, Part 2: Dicotyledoneae. Smithsonian Institution, Washington, D.C. 1991
Robert A. DeFilipps. Useful Plants of the Commonwealth of Dominica. West Indies. Smithsonian Institution, Washington, D.C. 1998