As implied by the term summer squash, zucchini's prime season is May to August, although they are now available year-round. Summer squash has a thin, soft skin and soft edible seeds, whereas winter squash has a hard skin.
The zucchini is a long, cylindrical vegetable, slightly smaller at the stem end, usually dark green in color. The flesh is a pale greenish-white and has a delicate, almost sweet flavor. Zucchini fruit grows quickly and is harvested within 2 to 7 days of flowering. Over-ripe zucchini and those past their prime can be bitter, but that didn't stop a New York gardener from growing the world's longest zucchini -- a whopping 69 and a half inches!
Newer varieties include the golden zucchini and the globe or round zucchini. The golden variety is somewhat milder in taste than the dark green. The globe variety is about the size of a softball, about 3 inches in diameter -- perfect for stuffing. Zucchini is not to be confused with marrow squash (also called vegetable marrow) which looks like a larger, more round version of the zucchini with white stripes.