Acorn squash (Cucurbita pepo var. turbinata), also called pepper squash or Des Moines squash, is a winter squash with distinctive longitudinal ridges and sweet, yellow-orange flesh. Although considered a winter squash, acorn squash belongs to the same species as all summer squashes (including zucchini and yellow crookneck squash). Acorn Squash is commonly mistaken as a gourd.The most common variety is dark green in color, often with a single splotch of orange on the side or top.