Pumpkins, Squashes, and Gourds (Cucurbita L.) of North America

Pumpkins and squash (Cucurbita L. spp.) include six independently domesticated crop species and subspecies that are grown worldwide for their edible fruits and seeds and for ornamental interest. Because domesticated pumpkins and squashes can be crossed with each other and with diverse primary genepool relatives, contributions from Cucurbita crop wild relatives (CWR) have enabled the development of disease-resistant cultivars and represent a vast pool of untapped genetic variability underlying traits including drought tolerance and disease resistance. Even so, thorough evaluations of these wild species for agronomically important traits are limited. The 12 Cucurbita crop wild relatives of North America are more narrowly distributed than they were in the past because of the extinction of megafaunal dispersers and because of habitat loss, and the genetic diversity of wild Cucurbita species may be decreasing; one North American wild relative, C. okeechobeensis (Small) L. H. Bailey ssp. okeechobeensis, is nearly extinct, and some others are rare. Ex situ and in situ conservation of these species that includes phenotypic assessments are needed to better utilize the wealth of genetic resources available for pumpkin and squash crop improvement.