Heliotropium Linnaeus (1753: 130)

Melo, José Iranildo Miranda De, Paulino, Renan Da Cruz, Oliveira, Regina Célia De & Vieira, Diego Daltro, 2018, Flora of Rio Grande do Norte, Brazil: Boraginales, Phytotaxa 357 (4), pp. 235-260 : 251

2. Heliotropium Linnaeus (1753: 130) .

Herbs or erect, decumbent or prostrate subshrubs. Leaves alternate, rarely verticillate, subopposite or opposite, sessile or petiolate. Inflorescences scorpioid, terminal, falsely terminal and/or axillary, with or without bracts. Flowers subsessile or sessile; calyx lobes of unequal length, partially united; corolla white or purplish with a yellow throat, or entirely yellow, tubular-salverform or obcampanulate, externally strigose, hispid, glabrous or pubescent externally and internally, mainly on the throat; lobes of different forms, margin undulate to undulate-plicate. Stamens subsessile or sessile; anthers introrse, free or coherent. Ovary 2-locular, sometimes 4-locular by the formation of a septum; ovules 1–2 per locule; style terminal; stigma of different forms, sessile or not. Schizocarp of 2 nutlets with 2 seeds or of 4 nutlets with 1 seed each; calyx persistent, accrescent or not. Seeds oblong-elliptic or trigone.

Comprises about 300 species, distributed in tropical and subtropical regions worldwide, predominantly in open arid and semiarid environments ( Frohlich 1981). In Brazil, nine species have been recorded ( Melo & Semir 2008), with two of them for Rio Grande do Norte, in the caatinga, including mountainous areas.