Squash and melons belong to the cucurbit family (Cucurbitaceae), which also includes cucumbers and gourds. Members of this family are divided into groups and have a tendency to hybridize easily one of other members of the identical group, but not between different groups. For example, squash and melons do not cross with each other, but varieties of squash will cross with gourds or other squash varieties. Muskmelons will cross with casaba melons or Armenian cucumbers and watermelon will unite with citrons. This will make identification of particular varieties hard.
Look carefully at the shape of the leaf. Identify watermelon leaves by their dark green color, prominent veins and three lobes which are split into additional lobes. Search for leaves that are rounded or heart shaped and have rounded lobed edges to spot cantaloupe and honeydew muskmelons.
Pick out pumpkins and closely related squash by their very big, dark green slightly lobed leaves. Distinguish other squash by big leaves which have 3 to 5 rounded lobes.
Inspect the stem for spines or prickles, which characterize most squash. Recognize summer squash by its bushy form and winter squash by demanding vining stems. Identify smaller vining stems with tendrils as melons or cucumbers.
Compare the magnitude of trumpet-shaped yellowish blooms. Differentiate melons by their much smaller flowers and squash by big flowers, two or three inches long. Examine the tiny green fruit forming at the base of the feminine flowers to ascertain what mature fruit it looks.
Cut open and flavor a fruit that is ripe. Assess the hardness to find out if it is a winter squash, which must be cooked to soften the flesh enough to eat, a summer squash, that includes firm flesh or a soft-fleshed melon. Evaluate whether the fruit has the sweet flavor of a melon or even the more dull flavor of squash.