Genus Detarium in Subfamily Detarioideae

Genus Description

Detarium (Leguminosae: Detarioideae) comprises approximately five species of evergreen or briefly deciduous trees and shrubs with a Sudanian–Guinean savanna distribution from Senegal to Uganda (POWO, 2024; GBIF, 2024). The type species is commonly cited as Detarium senegalense J.F.Gmel., and the genus is morphologically defined by paripinnate leaves with entire margins, minute stipules, terminal or axillary paniculate inflorescences with small bracteolate flowers, a cupular hypogynous disc, a single superior ovary with marginal placentation, and compressed–flattened drupes containing a single large seed (Burkill, 1985). Detarium is distinguished from the related Copaifera by its stipellate leaves and minute, caducous stipules, by its paniculate (rather than spike-like) inflorescences, and by consistently bearing one ovule per ovary.

The main centers of diversity lie in the Sudanian and Guinean woodlands and forest–savanna mosaics, with D. senegalense and D. microcarpum the most widespread taxa and several narrowly distributed taxa restricted to Sudanian or Congolian sectors. Species typically occur on well‑drained uplands, in open woodlands and scrub, from near sea level to mid‑elevations, and are characteristic of fire‑prone savanna landscapes (Burkill, 1985; WFO, 2024). Beyond the two widespread species, taxonomic limits and species counts remain unsettled, with several names treated as varieties or synonyms of D. senegalense by different authors (Burkill, 1985; Bezard & Baudran, 1978).

While fruit morphology is well documented, pollination and dispersal ecology remain inadequately documented for the genus as a whole; the hard, compressed drupes appear adapted to animal ingestion and gravity‑assisted seed movement, but comprehensive field studies are lacking. Chromosome counts are recorded in some accessions, but no single base number can be unequivocally stated for the genus at this time without further cytogenetic corroboration.

Molecular systematic studies confirm the placement of Detarium in Detarioideae within a broader Detarieae clade and support its generic distinctness from closely allied genera; recent phylogenies place the genus within a grade that includes Copaifera and Tessmannia sensu lato (Bruneau et al., 2008; Discovery, 2011). Subgeneric sections are not consistently applied, and taxonomic treatments vary: some authors include Guibourtia coleosperma as a fourth species, while others recognize five or more species across the savanna arc (Burkill, 1985; Bruneau et al., 2008). Ongoing plastid and nuclear sampling is gradually clarifying boundaries and geographic patterns of endemism.

Detarium is of moderate economic importance. D. senegalense yields heavy, durable timber used locally for construction and implements, while the sweet, oily pulp of D. microcarpum fruits is valued in regional markets; the trees are occasionally cultivated for shade or avenue planting, but the genus remains primarily wild-harvested (Burkill, 1985). Invasive tendencies are not reported.

Population status is insufficiently known across much of the range. Principal threats are deforestation for agriculture and charcoal, habitat fragmentation, and overexploitation of products from limited remaining stands. Baseline assessments and demographic monitoring are therefore needed to ensure the persistence of savanna populations (POWO, 2024).

• Detarium macrocarpum (Harms)
• Detarium microcarpum (Guill. & Perr.)
• Detarium senegalense (J.F.Gmel.)