Hesperelaea is a plant genus with only one species, probably now extinct. Hesperelaea palmeri was found only on Guadalupe Island, a small island in the Pacific Ocean, part of the Mexican state of Baja California, about 400 km southwest of Ensenada. The last collection of the plant on the island was in 1875, so the species and the genus must now be presumed extinct. An intensive search for the plant in 2000 was unsuccessful.
At the time of the collection of the type material in 1875, Hesperelaea palmeri was found only in a single canyon on the east side of the island. It was a shrub with broadly lanceolate leaves up to 5 cm long. Flowers were pale yellow, the petals over 10 mm long. The species was unusual in the family in having fully distinct petals.
The phylogenetic placement of Hesperelaea palmeri was investigated based on organellar DNA data (plastome and mitogenome) and nuclear DNA regions. Molecular dating suggests an Early Miocene divergence between Hesperelaea palmeri and its closest relatives (Forestiera and Priogymnanthus) confirming that this species was a paleoendemic lineage that likely predates the age of Guadalupe Island.
- Kew World Checklist of Selected Plant Families, Hesperelaea palmeri
- JP Redman, TA Oberbauer, JL León de la Luz. 2000. La flora de Isla Guadalupe y sus islotes adyacentes, Baja California, México. Instituto Nacional de Ecología, México D.F.
- Gray, Asa. 1876. Proceedings of the American Academy of Arts and Sciences 11: 83, Hesperelaea palmeri
- Shreve, F. & I. L. Wiggins. 1964. Vegetation and Flora of the Sonoran Desert 2 vols. Stanford University Press, Stanford.
- Zedane, L., Hong-Wa, C., Murienne, J., Jeziorski, C., Baldwin, B.G., & Besnard, G. 2016. Museomics illuminate the history of an extinct, paleoendemic plant lineage (Hesperelaea, Oleaceae) known from an 1875 collection from Guadalupe Island, Mexico. Biological Journal of the Linnean Society 117: 44-57.
- Van de Paer, C., Hong-Wa, C., Jeziorski, C., & Besnard, G. 2016. Mitogenomics of Hesperelaea, an extinct genus of Oleaceae. Gene 594: 197-202.