Vegetable Research & Information Center, UC Cooperative Extension

Frequently Asked Questions


1. What is the difference between a fruit and a vegetable?

A vegetable is the edible portion of a plant. Vegetables are usually grouped according to the portion of the plant that is eaten such as leaves (lettuce), stem (celery), roots (carrot), tubers (potato), bulbs (onion) and flowers (broccoli).

A fruit is the mature ovary of a plant. So a tomato is botanically a fruit but is commonly considered a vegetable. According to this definition squash, pepper and eggplants are also fruits. Then there are seeds such as peas which are also considered vegetables.

The Funk & Wagnalls Multimedia Encyclopedia has the following definitions:

Vegetable, the edible product of a herbaceous plant-that is, a plant with a soft stem, as distinguished from the edible nuts and fruits produced by plants with woody stems such as shrubs and trees. Vegetables can be grouped according to the edible part of each plant: leaves (lettuce), stalks (celery), roots (carrot), tubers (potato), bulbs (onion), and flowers (broccoli). In addition, fruits such as the tomato and seeds such as the pea are commonly considered vegetables.

Fruit, mature ovary in flowering plants, together with all inseparably connected parts of the flower. In strict botanical usage, the meaning may be restricted to the ovary alone. Commonly the term fruit is often restricted to succulent, edible fruits of woody plants, to melons, and to such small fruits as strawberries and blueberries. In nature, fruit is normally produced only after fertilization of ovules has taken place, but in many plants, largely cultivated varieties such as seedless citrus fruits, bananas, and cucumbers, fruit matures without fertilization, a process known as parthenocarpy. In either case, the maturation of the ovary results in the withering of stigmas and anthers and enlargement of the ovary or ovaries. Ovules within fertilized ovaries develop to produce seeds. In unfertilized varieties, seeds fail to develop, and the ovules remain their original size. The major service performed by fruit is the protection of developing seeds. In many plants, fruit also aids in seed distribution.

2. How can you tell when a watermelon is ripe?

From the publication "Watermelon Production in California": The criteria for picking watermelons include color change (the most reliable), blossom end conditions, and rind roughness. Watermelons do not separate from the vine when ripe; a sharp knife is used to cut melons from the vines. Melons pulled from the vine may crack open.

From "Home garden watermelons": To test melons for ripeness, rap the side of the fruit with your knuckles. A light or metallic sound means that the fruit is still green; a dull sound means it is ripe. This is most reliable in the early morning. During the heat of the day or after melons have been picked for some time, they all sound ripe. Fruits have a "ground spot" where they rest on the ground; this spot turns slightly yellow as the fruit matures. Watermelons tend to become rough as they mature. The tendrils closest to the fruit darken and dry up as the fruit ripens. Do not pull melons off the vine; use a sharp knife for cutting.

3. The leaves of my tomato plants are curled, the stems have bumps and the lower leaves turn yellow and fall off. Is something wrong?

This describes a normal tomato plant. It is natural for the leaves of tomato plants to curl under. The bumps on the stalk are normal and many tomatoes have them. They are actually nodes and if the stem were placed in a glass of water roots would grow out of the nodes. The lower leaves of the tomato plant usually turn yellow and fall off as the plant grows up.

4. The fruit on my zucchini plant do not grow but instead shrivel up and fall off. What is wrong?

Squash, cucumber and melons require insects, usually honeybees, to pollinate the flowers. When no insects are available, the fruit is not pollinated and so it shrivels up and falls off the plant. When no bees are present in the garden or the bee
population is too low for good fruit set, the dedicated gardener can substitute for the bee by pollinating by hand. Hand pollination is a tedious chore, but it is the only means of obtaining fruit set in the absence of bees.

The pollen is yellow in color and produced on the structure in the center of the male flower. You can use a small artist's paintbrush to transfer pollen, or you can break off a male flower, remove its petals to expose the pollen-bearing structure, and roll the pollen onto the stigma in the center of the female flower. When hand pollinating, it is important to use only freshly opened flowers. Flowers open early in the morning and are receptive for only one day.

The female flower in cucurbits can be recognized easily by the presence of a miniature fruit (ovary) at the base of the flower. Female squash flowers are much larger than the female flowers on melon and cucumber plants. The male squash flower can be identified by its long, slender stem. The female squash flower is borne on a very short stem.

In melons and cucumbers, male flowers have very short stems and are borne in clusters of three to five, while the females are borne singly on somewhat longer stems.

For more detailed information read the publication “Fruit Set Problems in Squash, Melons, and Cucumbers In Home Gardens."

Contact Us

Mailing address:
UC Vegetable Research & Information Center
Dept. of Plant Sciences, Mailstop 4
One Shields Avenue
Davis, CA 95616

Phone: (530) 752-1748

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Last updated: August 21, 2020
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