Endemic to the island of Hawaii, on old lava flows or old cinder cones in dry shrubby or forested habitats from 1000–2000 m elevation.
Solanum incompletum is a member of subgenus Leptostemonum (the spiny solanums) and within that clade a member of section Irenosolanum.
Once thought to be extinct this species persists on the United States Army Pōhakuloa Training Area. Several conservation measures have been taken since the discovery of living material, including ex situ conservation and fencing of in situ individuals. Threats to this species include seed predation by rats, herbivory by feral goats, and destruction from military training (VanderWerf et al., 2008). This is the only species of section Irenosolanum with prickles sometimes present on the calyx. Wagner et al. (1999) listed S. incompletum as endangered. My recognition of S. hillebrandii which Wagner et al. (1999) included under S. incompletum will not alter the conservation status of S. incompletum as no living individuals S. hillebrandii would be “removed” from the population of S. incompletum.
Dunal (1952) named this species from the sterile, and thus incomplete, material collected by David Nelson on Captain Cook’s third voyage.
Dunal,,M.-F. 1852. Solanaceae. In: A. P. De Candolle (ed.), Prodromus Systematics Naturalis Regni Vegetabilis 13: 1–690.
VanderWerf, E., L. Young & B. Keitt. 2008. Predator-proof Fencing for Invasive Species Control in Hawaii: A Comprehensive Prioritization and Implementation Plan to protect native species. Project Report (project 07-339). Department of Defense Legacy Resource Management Program.
Wagner, W.H., D.R. Herbst & S.H. Sohmer. 1999. Solanaceae. Manual of the Flowering Plants of Hawaii. University of Hawaii Press, Honolulu, Hawai'i.
Endangered (Wagner et al. 1999).