PlantaeDB Logo
Login Sign-up

Genus Thevetia in Subtribe Thevetiinae

In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.

Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.

Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).

Do you wish to read more about plant taxonomy? Click here!

Genus Description

Suggest a correction!

Thevetia is a small genus of milky‑sapped shrubs and trees in the family Apocynaceae, subfamily Rauvolfioideae (APG IV, 2016). About eight species are currently accepted (POWO, 2024; WFO, 2024), with Thevetia peruviana—the widely cultivated yellow oleander—serving as the most familiar taxon. The genus occurs from southern Mexico through Central America to northern South America and the Caribbean, inhabiting low‑land tropical forest edges, secondary scrub and coastal dunes.

Diagnostic traits separate Thevetia from closely related genera. Plants reach 2–6 m, bearing opposite or whorled, simple, entire, glossy leaves that lack stipules. Flowers are borne in terminal or axillary thyrses; each flower has a long, trumpet‑shaped corolla (3–5 cm) with five spreading lobes, emitting a strong night fragrance. Stamens attach to the corolla throat, forming a pollinium‑like structure. The superior, bicarpellary ovary carries many ovules on axile placentas and matures into a fleshy drupe containing one to five seeds.

Species richness concentrates in the Amazon basin and Guiana Shield, with several endemics, such as Thevetia ahouai on Caribbean islands. Most taxa occupy sea level to about 800 m, with some reaching 1200 m. Its distribution follows a classic Neotropical pattern, reflecting dispersal across the Central American land bridge.

Intrinsic biology remains incompletely known. The nocturnal, scented corollas strongly indicate hawkmoth pollination, a hypothesis supported by field observations of hawkmoth visits to Thevetia peruviana (Goyder et al., 2012). Fruit dispersal is likely by birds or mammals attracted to the brightly coloured drupes, though experimental data are scarce. The milky latex, common in Apocynaceae, is present in all Thevetia species.

Taxonomically, Thevetia has traditionally been treated as distinct, but molecular phylogenies place it within the Cascabela clade, prompting some authors to synonymize it under Cascabela (Simões et al., 2019). Major databases, however, continue to list Thevetia as an accepted genus (POWO, 2024; WFO, 2024), reflecting unresolved circumscription.

Human relevance centers on horticulture; Thevetia peruviana is a popular ornamental but invasive in Florida and Hawaii (WFO, 2024).

Conservation assessments are limited; Thevetia ahouai is listed as Near‑Threatened, and habitat loss threatens several narrow endemics (POWO, 2024). Clarifying the phylogenetic relationship between Thevetia and Cascabela will be essential for accurate species delimitation and future conservation planning (Simões et al., 2019).

Pick a Species to see its components: