Botany

Discovering Botanical Families: Cucurbitaceae

Cucurbits ignore conventions and disregard the boundaries imposed on them by vegetable patches and gardens. Invading every space around them without hesitation, they travel across lawns and flower beds. They climb over fences and railings, clinging to arbors and trellises with their powerful tendrils. Cucurbits create stunning vertical displays. When autumn is in full swing, they beautifully color the fields with their large fruits and contribute to the success of our Halloween portraits. More specifically, the Cucurbitaceae family consists of annual and perennial herbaceous plants, and more rarely shrubs. It is a family of dicotyledonous plants comprising 800 species divided into 180 genera, mainly native to tropical or subtropical regions.

The pumpkin, a proud representative of the Cucurbitaceae family. Photo: Mathieu Gaudreault

Morphological Characteristics

Stems, Leaves, and Tendrils

The stems are usually creeping or climbing. They often have axillary tendrils (branched or simple). Tendrils are modified leaves. Here, evolution has caused some leaves to gradually transform into small lassos that allow the plant to cling on and climb. These tendrils are incredibly strong and can support plants bearing very heavy fruit.

The tendrils found on most Cucurbitaceae make them excellent climbing plants. Photos: Mathieu Gaudreault

As there are always exceptions, zucchini squash (Cucurbita pepo var. cylindrica) are neither climbing nor creeping and do not have tendrils. However, they meet other important criteria relating to flowers and fruit, allowing them to be classified as part of this family.

Zucchini squash (Cucurbita pepo var. cylindrica) with a bushy growth habit. Photo: Mathieu Gaudreault.

The leaves are alternate, often broad, palmate, and lobed. There are Cucurbits with compound leaves, but keep in mind that most have simple leaves like those shown below.

A and B: Leaves with palmate veins. C: Lobes present on Cucurbitaceae leaves. Illustration: Mathieu Gaudreault

The stems and leaves have hairs (trichomes), which can be simple or glandular. These hairs are usually stiff, making the plants rough to the touch and not always pleasant to harvest.

Hairs (trichomes) on stems and leaves. Photo: Mathieu Gaudreault

Flowers

Plants in this family are monoecious, meaning that male and female flowers are found on the same individual. Female flowers are distinguished by their ovary located beneath the flower. Symmetry is often actinomorphic (radial). The corolla generally has five fused petals, and the calyx often has five sepals.

A: Male flower B: Female flower. The bulge (ovary) beneath the petals makes it easy to distinguish between male and female flowers in Cucurbitaceae. Illustration: Mathieu Gaudreault

Fruits

The fruit is a pepo, a specialized type of berry with a tough skin (epicarp) and fleshy pulp (mesocarp). This is the case with squash, pumpkins, melons, etc. Inside, the seeds are often arranged in three compartments, sometimes surrounded by pulp, as in cucumbers.

The melon fruit is a good example of a pepo. A: Leathery rind (epicarps). B: Flesh (mesocarp). The three compartments can also be seen.. Source: Wikipedia

Here Are Some Well-Known Examples and Others Less So of Cucurbits.

Pumpkin ‘Celebration’ (Cucurbita pepo var. turbinata ‘Celebration’) Cucurbits now offer us a wide variety of colorful and tasty pepo gourds. Photo: Mathieu Gaudreault
You are probably familiar with zucchini (Cucurbita pepo var. cylindrica). But did you know that its flowers are edible? A: Female flowers, B: Male flowers. Photo: Mathieu Gaudreault.
The wild cucumber (Echinocystis lobata) is a species native to Canada. Here we see three important characteristics of Cucurbitaceae: tendrils, palmate leaves, and pepo-type fruits. Photo: Mathieu Gaudreault.
Loofah (Luffa aegyptiaca). Cultivated as a vegetable when young, this cucurbit produces a natural fiber used as a vegetable sponge when it ripens and dries. A fine example of a plant that is both useful and surprising! Source: Tomas Nevado, Wikipedia

The Biggest Pumpkin in the World!

The family also holds its own record! In 2023, Travis Gienger, a horticulture teacher from Minnesota, broke the Guinness World Record for the largest pumpkin in the world. It weighed 2,749 pounds! Source: hmbweighoff.com

In many ways, cucurbits are a fascinating family: with their vigorous growth and oversized, colorful fruits, they don’t just take up space, they transform it. Their tropical and subtropical origins do not prevent them from inspiring garden designers in temperate climates. They will not disappoint you, as long as you provide them with compost-enriched soil, warmth, and regular watering.

Success guaranteed!

In Summary, to Identify a Cucurbitaceae:

  • Climbing or creeping plant with often rough stems
  • Alternate, palmate leaves
  • Presence of hairs
  • Flowers with 5 petals and unisexual (male and female flowers)
  • Pepo-type fruit

In our next installment… the Euphorbiaceae!

Chantal Gauthier and Mathieu Gaudreault are both horticulturists and teachers at the Centre de formation Fierbourg in Quebec City, in the Horticultural Production and Horticulture and Garden Center programs. Passionate about the plant world, they enthusiastically scour botanical gardens, parks, forests and horticultural events, always on the lookout for inspiring finds. Their infectious passion is passed on not only to their students, but also to those around them, earning them the nickname Plant geeks.

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