PlantaeDB Logo
Login Sign-up

Genus Rehmannia in Family Orobanchaceae

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!

Rehmannia (Libosch. ex Fisch. & C.A.Mey.) is a small genus of herbaceous perennials placed in Orobanchaceae (POWO, 2024; APG IV, 2016). Approximately six species are currently accepted, with a core distribution in temperate East Asia ranging from the Korean Peninsula through central and southern China to northern Vietnam (POWO, 2024). The type species, Rehmannia glutinosa, anchors the generic circumscription (Hong & Wen, 2020). Plants form rosettes with opposite, often deeply lobed leaves covered in a dense stellate indumentum; stipules are absent. Flowering stems are erect, bearing terminal racemes or spikes. Flowers are bilabiate with a tubular, five‑lobed corolla that varies from pink to violet; the inferior ovary possesses axile placentation, and the fruit is a loculicidal capsule containing numerous minute seeds (Tank et al., 2022).

Centers of diversity lie in the mountainous regions of central and southern China, with several taxa endemic to isolated provinces; species also occur in Korea and Japan, illustrating a classic Sino‑Japanese biogeographic pattern (Li et al., 2021). Typical habitats include forest understory, shaded slopes and rocky outcrops at elevations of 200–2000 m.

Pollination is primarily by bees and flies attracted to the nectar‑rich corollas, while the light, winged seeds are wind‑dispersed (Hong & Wen, 2020). Chromosome counts consistently show 2n = 28, indicating a base number of x = 14 (Li et al., 2021).

Taxonomically, Rehmannia was long placed in Scrophulariaceae but molecular evidence places it firmly within Orobanchaceae (APG IV, 2016). Authors have recognised two subgenera, R. subg. Rehmannia and R. subg. Pentapterygium, although recent treatments treat the group as a single, morphologically coherent lineage (Hong & Wen, 2020). Some synonymisation of local variants has been proposed, but species limits remain debated (Tank et al., 2022).

Humans appreciate the genus for ornamental horticulture; R. glutinosa and R. elata are cultivated for their showy flowers and occasionally escape into disturbed sites, where they may behave as casual weeds. No timber or significant medicinal use is reported here.

Conservation assessments indicate that several narrow‑endemic taxa suffer from habitat loss and over‑collection, warranting continued field surveys and ex situ conservation. Continued integration of phylogenomics and demographic monitoring will be essential to refine species limits and prioritize protection for this East Asian lineage.

Pick a Species to see its components: