PlantaeDB Logo
Login Sign-up

Genus Hydnocarpus in Family Achariaceae

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!

Hydnocarpus (Gaertn.) belongs to the family Achariaceae (APG IV, 2016) and includes roughly 42 accepted species (POWO, 2024). The genus occurs throughout tropical Asia, from India and Sri Lanka to Malesia and New Guinea, with a few taxa in West and Central Africa (WFO, 2024). Historically it was treated in Flacourtiaceae, a view reflected in many regional treatments.

Plants are dioecious trees up to 30 m tall with simple, alternate leaves bearing small caducous stipules. Axillary or terminal racemes bear unisexual flowers with five sepals, five free petals, a nectary disc, and numerous stamens in male flowers; the superior ovary contains two to five carpels with axile placentation. Fruit is a drupe with a single seed.

Diversity is highest in Malesia, where many species are rainforest endemics on Borneo, Sumatra, and the Philippines. Additional centers lie in mainland Southeast Asia, the Indian subcontinent, and the foothills of the Himalayas up to about 1 500 m. A small African group, including Hydnocarpus bracteatus and Hydnocarpus longipes, occupies lowland forest of West and Central Africa (Barlow, 1997), reflecting past Indian‑Ocean dispersal routes.

Floral morphology suggests entomophily; the prominent nectar disc likely attracts bees or flies (Chase et al., 2016). Mature drupes are bird‑ and mammal‑dispersed, aiding long‑range colonization. The trees are fast‑growing hardwoods that regenerate vigorously after disturbance, a trait that has allowed many species to persist in logged forests.

Current systematic placement in Achariaceae follows APG IV (2016) and is supported by plastid phylogenies (Chase et al., 2016). Earlier classifications placed Hydnocarpus in Flacourtiaceae, a view still reflected in many regional checklists (WFO, 2024). Formal subgeneric sections are not universally accepted; Barlow (1997) proposed informal species groups based on leaf and inflorescence traits. Recent synonymizations include Hydnocarpus tonkinensis reduced to Hydnocarpus mcnabianus (Barlow, 1997), illustrating ongoing revision.

Some species are harvested for hardwood timber, and the oily seeds of Hydnocarpus wightianus and Hydnocarpus laevigatus have historically been exploited for lamp oil. Trees are occasionally planted as shade or ornamental specimens in botanical collections, but they remain minor in commercial horticulture. The genus does not behave as a serious weed.

Habitat loss, logging, and over‑exploitation threaten many taxa, and several are assessed as Near‑Threatened or Endangered on the IUCN Red List. Taxonomic ambiguities and limited field data impede targeted conservation actions. A forward‑looking effort combining molecular phylogenetics, population monitoring, and sustainable management will be crucial to safeguard remaining species.

Pick a Species to see its components: