PlantaeDB Logo
Login Sign-up

Genus Frangula in Family Rhamnaceae

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!

The genus Frangula (authority Mill.) belongs to the family Rhamnaceae. It comprises approximately 45 species of deciduous shrubs and small trees distributed across temperate regions of the Northern Hemisphere, spanning North America, Europe, and Asia. The type species is Frangula alnus (POWO, 2024; WFO, 2024).

Morphologically, Frangula is distinguished by alternate, simple leaves that are entire to finely serrate and bear small, caducous stipules. Leaves are often smooth or slightly pubescent, and the axillary inflorescences are typically cymes or short panicles bearing greenish‑white flowers with five sepals, five petals, a nectariferous disc and five stamens. The ovary is superior, usually two‑ or three‑locular with axile placentation, and the fruit is a drupe containing a single stone. Deciduous stipules and the disc separate Frangula from Rhamnus (Stace, 1997).

Species richness peaks in North America and East Asia, where several endemic taxa occur in forests and wetland margins. These habitats range from riverbanks to mountain slopes. Frangula californica is confined to the Pacific Coast, Frangula crenata to Japan, and Frangula alnus has a broad Eurasian distribution from lowlands to subalpine elevations (POWO, 2024). Many species occupy moist, shaded habitats, contributing to understorey diversity in temperate deciduous and mixed forests.

Pollination is insect‑mediated by bees and syrphid flies, and the nectar disc also attracts beetles, while the fleshy drupes are eaten by birds and small mammals, facilitating long‑distance seed dispersal. Chromosome counts report a base number of x = 12, with most taxa diploid (2n = 24) (Stace, 1997). No unusual life‑history traits beyond these reproductive attributes have been recorded.

Historically, Frangula was treated as a section of Rhamnus, but molecular phylogenies have shown it to be a distinct clade within Rhamnaceae (Richardson et al., 2000; Medan & Schirarend, 2004). Modern classifications retain Frangula at generic rank, and while subgeneric delimitations have been proposed, none have gained widespread acceptance. Recent molecular work continues to resolve species limits, especially in North America.

Several species are cultivated as ornamental shrubs for their glossy foliage; F. alnus is popular in hedging and restoration plantings. In non‑native regions, notably North America, F. alnus has become naturalised and is considered invasive. Wood is not commercially significant, though some species provide valuable wildlife habitat.

While most Frangula species remain widespread, regional endemics face habitat loss, e.g., F. caroliniana is endangered in parts of the United States. Monitoring populations and clarifying species boundaries will aid conservation. Future research should focus on climate‑resilient propagation methods.

Pick a Species to see its components: