A
pumpkin is a
cultivar of a
squash plant, most commonly of
Cucurbita pepo, that is round, with smooth, slightly ribbed skin, and deep yellow to orange coloration. The thick shell contains the seeds and pulp. Some exceptionally large cultivars of squash with similar appearance have also been derived from
Cucurbita maxima. Specific cultivars of
winter squash derived from other species, including
C. argyrosperma, and
C. moschata, are also sometimes called "pumpkin". In
New Zealand and
Australian English, the term
pumpkin generally refers to the broader category called winter squash elsewhere.