Winter squash is a taxonomically diverse group of vegetables in the Cucurbita genus. Cultivars may belong to one of several species: Cucurbita pepo (acorn and spaghetti squashes), C. maxima (hubbard, buttercup, and kabocha), C. moschata (butternut), and C. mixta (cushaw). Because these squash are harvested when mature and rinds have hardened, most types can be stored for use during the winter.