Drupe

In botany, a drupe, also called a stone fruit, is a special kind of fruit. It has a soft, fleshy outside part made of the exocarp (skin) and mesocarp (flesh). Inside this soft part is a hard shell called a pip (in the UK), pit (in the US), stone, or pyrena. This hard shell protects a tiny seed, also called a kernel. Drupes do not open up to let the seed out; they are indehiscent.

These fruits usually grow from one carpel and often come from flowers with superior ovaries. The hard shell, made from lignified material, comes from the ovary wall of the flower. In some fruits made of many small parts, like a raspberry, each small part is called a drupelet. Even though we often call these berries, scientists have a different definition of berry.

Many flowering plants make drupes. Some examples include coffee, mango, olive, date, pistachio, and all fruits from the genus Prunus, such as the almond, cherry, peach, and plum. The word drupaceous describes a fruit that looks and feels like a drupe but does not exactly fit the scientific definition.

Description

Sometimes it's hard to tell if a fruit is a drupe or a berry. For example, some people say the avocado is a drupe, while others call it a berry.

A freestone is a drupe where you can easily take the hard part out from the soft part. A clingstone is a drupe where the hard part sticks to the soft part and is hard to remove. A tryma is a nut-like drupe. Fruits like hickory nuts (Carya) and walnuts grow inside a covering and are actually drupes, not true nuts.

Many drupes have a sweet outer layer that animals like to eat. When animals eat these fruits, they help spread the plant's seeds.

Examples

Some common fruits that are drupes include apricots, olives, loquat, peaches, plums, cherries, mangoes, pecans, and amlas (Indian gooseberries). The coconut is also a drupe, with a dry or fibrous outer layer and a hard shell inside.

Fruits like blackberries and raspberries are made up of many small drupes grouped together. Mulberries, which look similar to blackberries, are different because they grow together as one fruit. Some drupes grow in clusters on plants, such as dates and certain palms found in places like central Chile and the Sonoran Desert.

Even some plants not usually thought of as flowering plants, like cycads, ginkgos, and some cypresses, produce fruits that look like drupes.