Key to the species of Heliotropium

1Stigma an umbrella-shaped disc on a short style. Plant more or less succulent
1'Stigma conical or a ring-like structure surpassed by a tubular apical part. Plants not succulent
2Leaves broad, ovate to oblong
2'Leaves narrowly linear to lanceolate. Fruit not ribbed, separating into 4 nutlets
3Fruit separating into 2 bilocular pyrenes. Corolla villous inside
3'Fruit not dividing at all or separating into 4 unilocular nutlets. Corolla not villous inside
4Inflorescence corymbose, composed of branched cymes. Fruit separating into 4 nutlets
4'Inflorescence spike-like, elongate, not corymbose. Fruit remaining undivided.
5Apex of carpels profoundly bidentate; carpels 2.5-3 mm long, strongly divergent at last
5'Apex of carpels entire or slightly bidentate; carpels 4-5 mm long, not or scarcely divergent at last
6Inflorescence without bracts. Leaves elliptic to obovate, with silky hairs
6'Inflorescence with bracts, or flowers in axils of leaves
7Stems and branches more or less prostrate
7'Stems and branches erect or branches more or less divaricate
8Flowers single in axils of leaves, crowded apically
8'Flowers in terminal short, straight cymes, bracts and flowers alternating on each side
9Flowers in very dense cymes without any free space between them. Bracts sharply acute, needle-like. Tube of corolla long and slender, strongly inflated by the stamens, surpassing the calyx in length
9'Flowers not so dense, arranged in 3-8 mm distance of each other. Bracts not so sharply acute, not needle-like. Tube of corolla shorter, usually not or scarcely surpassing the calyx, only weakly inflated by stamens
10Style about 1.5 to 2.5 times as long as stigma. Calyx c. 2.5 mm long
10'Style about as long as stigma. Calyx c. 1.5 mm long