Heliotropiaceae Schrad., Commentat. Soc. Regiae Sci. Goett . Recent. 4: 192. 1819 nom. cons.

Type genus.

Heliotropium L.

Description.

Annual or perennial herbs, climbing shrubs or small trees. Leaves simple, alternate, exstipulate, petiolate or sessile; lamina linear to ovate, apex acute to acuminate, margin entire or revolute. Inflorescences terminal or axillary, spike-like, scorpioid, subcapitate or subcorymbose cymes; with or without bracts. Flowers 5-merous, rarely 4-merous, bisexual, actinomorphic. Calyx 5-lobed, divided almost to the base, lobes linear to ovate, entire, persistent. Corolla white to pinkish-white, purple, pale green or greenish to yellowish, campanulate to funnel-shaped, lobes orbicular. Stamens 5, filaments adnate to the corolla tube. Pistil ovary superior, bicarpellate, usually 4-loculate, 1 ovule per locule, nectar disc at the base surrounds the ovary; style terminal, with a conical stigma structure forming a basal ring around style. Fruit dry or fleshy, separating into four 1-seeded nutlets or two 2-seeded nutlets. Seeds straight or curved, with endosperm.

Two genera and 12 species are found in Thailand.