The question of whether a pumpkin is a squash is a common point of confusion, primarily because the answer depends on whether one is speaking botanically or culinarily. From a scientific perspective, the answer is unequivocally yes: a pumpkin is a type of squash. The confusion arises because “pumpkin” is an informal, cultural designation used to describe specific varieties of fruit within a much larger botanical group.
The Botanical Reality
All plants commonly called squash and pumpkin belong to the genus Cucurbita. Botanists have identified five domesticated species within this genus that are widely cultivated for human consumption: Cucurbita pepo, C. maxima, C. moschata, C. argyrosperma, and C. ficifolia. All true pumpkins, from small pie varieties to giant carving gourds, are simply cultivars of these five species.
Every fruit in the Cucurbita genus is defined by a specific structure called a pepo. A pepo is a specialized type of berry that develops from an inferior ovary and features a thick, hard outer rind and a fleshy interior containing the seeds. This thick outer wall technically makes all squashes and pumpkins a type of fruit, despite their common savory use in cooking. The diverse shapes and colors seen in species like the acorn squash (C. pepo) or butternut squash (C. moschata) are variations within this scientifically defined group.
Culinary Versus Scientific Naming
The general public’s uncertainty stems from the lack of a formal botanical definition for “pumpkin.” Unlike the genus Cucurbita, the term “pumpkin” is a cultural label, not a scientific one. It is generally applied to any round, orange, hard-rinded squash used for carving or for making sweet pies and desserts.
This distinction means a single species can produce both a “pumpkin” and a “squash” variety. For instance, Cucurbita pepo includes both the classic orange jack-o’-lantern pumpkins and green zucchini, which are visually and texturally quite different. In the United States, “pumpkin” is usually reserved for a specific type of round, hard-shelled Cucurbita, while “squash” is used for almost everything else in the genus.
Naming conventions vary significantly by region, adding to the confusion. In countries like Australia and New Zealand, “pumpkin” is the catch-all word for nearly all hard-skinned winter squash, including varieties North Americans call butternut or acorn squash. This highlights how tradition and local parlance influence the common name more than botanical taxonomy.
Winter Squash Versus Summer Squash
The practical classification of squash in the kitchen is divided into two primary categories: winter squash and summer squash. This culinary distinction is based on the maturity of the fruit at harvest and the resulting characteristics of the rind. Pumpkins are classified as winter squash because they share the traits of this group.
Winter squashes, including pumpkins, acorn squash, and butternut squash, are grown until they reach full maturity and develop a thick, hard rind. This tough outer shell allows them to be stored for extended periods, sometimes for months, making them available through the winter. They are typically harvested in the late summer or fall when the seeds inside are fully mature.
In contrast, summer squashes like zucchini, yellow squash, and pattypan squash are harvested while the fruit is still immature. This premature harvest results in a soft, edible skin and a much shorter storage life, requiring them to be consumed soon after picking. The difference between the soft, immature rind of a zucchini and the hard, mature rind of a pumpkin is the main factor separating these culinary groups.
The Broader Cucurbit Family
The Cucurbita genus, which contains all squashes and pumpkins, is part of the much larger plant family known as Cucurbitaceae. This family is commonly referred to as the gourd family and encompasses approximately 95 genera and nearly 1,000 species of flowering plants. Placing the pumpkin within this broader context shows its evolutionary relationship to many other familiar produce items.
Other prominent members of the Cucurbitaceae family include cucumbers, various melons, and gourds. For example, the cucumber belongs to the genus Cucumis, while watermelons are in the genus Citrullus. All these plants share common characteristics, such as being herbaceous vines with tendrils and producing a fleshy fruit derived from an inferior ovary.