The age-old question, “Is the tomato a vegetable or a fruit?” is pointless to the horticulturalist or the botanist. In everyday language, a vegetable is any plant that is eaten, with certain exclusions based on cultural and culinary customs. Fruits, on the other hand, is a specific part of a plant: A fertilized and ripened pistil (the ovary), including any other floral structures that ripen along with it.
The outer surface of a fruit is the pericarp and the inside contains the seed(s). A seed is a mature ovule (the egg), and is composed of the embryo, carbohydrates to nourish the embryo when it germinates, and a covering called a seed coat.
The various kinds of fruits are defined based on observable characteristics and also on what parts of the floral structure they developed from. It is sometimes impossible to tell just by looking at a fruit which type it is.
Simple Fruits develop from a single pistil
- Drupes have a rock hard pit that encloses a single seed. Examples are cherry, peach, olive and walnut.
- Pomes have one or more papery or hardened cores, each usually containing several seeds. Examples are apple and pear.
- Berries are fleshy throughout and may or may not have a hard or leathery outer skin.
- Typical berries are fleshy throughout. Examples are blueberry, grape, tomato, pepper, gooseberry.
- Pepos are berries with a hardened skin. Examples are watermelon, cucumber and squash.
- Hesperidiums are berries with a leathery skin and papery partitions within. Examples are the citrus fruits.
- Dehiscent Fruits split open at maturity to release their seeds.
- Legumes develop from a pistil with a single carpel and split along two seams. Examples are beans and peas.
- Follicles develop from a pistil with a single carpel and split along a single seam. Examples are milkweed, delphinium and columbine.
- Capsules develop from a pistil with two or more carpels and split open in any of several ways. Capsules are the most common kind of fruits.
- Valvate Capsules split open on their tips. Examples are campion, Jacob’s Ladder and primrose.
- Porose Capsules let the seeds out through holes near their tip. Examples are the poppies.
- Loculicidal Capsules split along the middle of the ovary. Examples are irises and lilies.
- Circumscissile Capsules split open around the middle, with the top coming off like a lid. Examples are moss rose and plantain.
- Septicidal Capsules split along the fusions between adjacent carpels on the ovary. Examples are azalea and Foxglove.
- Siliques are dry dehiscent fruits that are elongate and split open lengthwise down the middle and have a papery membrane between the two halves. Examples include the brassicas (cabbage, broccoli, mustard, etc.)
- Indehiscent fruits do not split open at maturity.
- Achenes are small, dry fruits that contain a single seed loosely attached to the pericarp. To the layman, achenes may look like actual seeds. Examples are sunflower, dandelion and buckwheat.
- Caryopsises are like achenes but the single seed is firmly fused to the outside skin. Examples are all the grasses, including cereal grains and corn.
- Samaras are achenes with a wing or two attached to the outside skin. Examples are maples, elms and ashes.
- Nuts are larger achenes with a thick, hard pericarp. Examples are acorn, hickory and chestnut.
- Schizocarps are dry indehiscent fruits with two or more sections from two or more carpels. The sections split apart at maturity but do not open to release their seeds. Examples are carrot, parsley and hibiscus.
- Aggregated fruits develop from more than one pistil. Examples are raspberry, strawberry and magnolia. The individual fruits within an aggregate may be drupes (raspberry), achenes (strawberry) or follicles (magnolia).
- Multiple fruits develop from multiple flowers, and in some cases, other parts of the inflorescence. Examples are pineapple, fig and mulberry.
“Knowledge is knowing that a tomato is a fruit, wisdom is not putting it in a fruit salad.” – Miles Kington