It turns out聽, not a common English one. Blackberries, mulberries, and raspberries are not berries at all, but bananas, pumpkins, avocados and cucumbers are. So what makes a berry?
聽has seeds and pulp (properly called聽鈥減ericarp鈥�)聽that develop from the ovary of a flower. The pericarp of all fruit is actually聽聽into 3 layers. The exocarp is the skin of the fruit, and in berries it鈥檚 often eaten (like in grapes) but not always (like in bananas). The mesocarp is the part of the fruit we usually eat, like the white yummy part of an apple, or the bulk of a plum, though in citrus fruits the mesocarp is actually the white, sort of inner-peel that we remove. Last is the endocarp, which is the closest layer that envelopes the seeds. In stone fruits, it鈥檚 the stone. In many fruits, it鈥檚 actually a membrane that we don鈥檛 really notice, often because it鈥檚 been bred to be thin, like in bananas. In citrus, the endocarp is actually the membrane that holds the juicy parts of the fruit, that is, the part you don鈥檛 want to pierce unless you want to get sticky.
If most fruit have these 3 layers, then why are berries special? It鈥檚 mostly due to the nature of their endocarps. Although not exactly quantified, berries generally have thin endocarps and fleshy (not dry) pericarps. Of course, these rules aren鈥檛 rigid, as watermelons and citrus fruits are berries, and neither are thought to have especially thin skins.
So if your favourite fruit isn鈥檛 a berry, what might it be? If it has a thick, hard endocarp, it鈥檚 probably a聽, a fancy term for a stone fruit. This group encompasses apricots, mangoes, cherries, olives, avocados, dates and most nuts. Basically, if you wouldn鈥檛 want to just bite into it, it鈥檚 probably a drupe.
If your snack has a core, it鈥檚 probably a聽. From聽its聽name you probably guessed that this bunch includes apples, as well as pears. If you鈥檙e a bit more adventurous, your favourite breakfast might include a聽, which is a fruit that is actually make up of a cluster of fruiting bodies. Some examples of this are pineapple, figs and mulberries. These fruits turn out to be part of a greater group called聽, in which the fruit (or many fruiting bodies) is not derived from the ovary, but some other part of the developing plant. This is where the 鈥渘ot-a-berry" strawberry falls.
Finally, if you, like me, consider your favourite fruit to be a raspberry or blackberry, then you love聽. These are formed by many ovaries merging to become one flower, and most are also accessory fruits.聽Botany is weird, isn鈥檛 it?聽
Berry weird.
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