The seed coat furnishes protection with a thick cuticle, tannin cells, mucilage, and a hard sclerotesta. The external layer of the seed coat is a sarcotesta; a thick cuticle covers the external walls of its epidermal cells. This epidermis bears stomates and, in the early stages, trichomes. The subepidermal cells have druses. Starch grains are abundant in the sarcotesta from June through August, but they disappear during dispersal in September. The parenchyma is interrupted by mucilage canals lined by epithelial cells. Tannin cells are found in the sarcotesta, sclerotesta, and pachychalaza. Ten sectors of an areole in the sclerotesta around the micropyle may correspond to the tips of the integumentary segments in some fossil plants, such as Genomosperma kidstonii.