Stone fruits, nuts, and berries

Posting about flowering pear trees reminded me of some complexities in the classification of fruits. Putting aside the well-known divergence between the use of the word fruit in botany and its use in cooking and dining contexts, I’ll look at some more specific cases, in particular stone fruit(s). Again, there’s a divergence between the technical terminology of botany and ordinary language — a result of botanists having taken over ordinary vocabulary and employed it as technical vocabulary in specialized senses.

From Wikipedia, with two technical usages, a broader one and a narrower one:

Stone fruits (or stonefruits or stonefruit), in botany, refers to drupes, fruits in which an outer fleshy part (exocarp, or skin; and mesocarp, or flesh) surrounds a shell (the pit or stone) of hardened endocarp with a [large, hard] seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries. The definitive characteristic of a drupe is that the hard, lignified stone (or pit) is derived from the ovary wall of the flower.

More specifically, “stone fruit” refers to members of the genus Prunus, which includes plums, cherries, peaches, apricots and almonds [and nectarines, and various hybrids, and some less common fruits, like damsons]. [All members of the genus are drupes.]

In the broader technical usage, stone fruit is simply a synonym for drupe. This takes in a great many things that aren’t stone fruits in ordinary English (in the context of cooking and eating):

Some flowering plants that produce drupes are coffee, jujube, mango, olive, most palms (including date, coconut and oil palms), pistachio, white sapote, and all members of the genus Prunus (link)

(Note that stone fruit in both the technical and ordinary usages is ambiguous between reference to a fruit (in the botanical sense) and to the plant that produces that fruit.)

Even the narrower technical usage takes in at least one plant (and its fruit) that would never be referred to as a fruit in ordinary English: the almond. A photo of almond fruits (in the botanical sense) on the tree:

You won’t find these for sale in a grocery story. This botanical drawing exposes some of the complexity of almond anatomy and commerce:

Wikipedia explains:

The fruit of the almond is a drupe, consisting of an outer hull and a hard shell with the seed (which is not a true nut [in the botanical sense]) inside. Shelling almonds refers to removing the shell to reveal the seed.

The outer hull has a a skin with the flesh of the fruit inside, and then the shell inside that, and then the seed inside *that*. The flesh is always removed for sale; the shells can then be sold as they are, with the seeds inside, or the shells can be removed and the seeds sold (as “nuts”, in ordinary usage); and in fact the brown seedcoat can be removed, and the white embryo inside it sold as a blanched almond.

I’ll get to nut in a while. Some fruits in the rose family (not in the genus Prunus) are (botanically) pomes rather than drupes: apples, pears, quinces, loquats, and some others.

A pome is an accessory fruit composed of one or more carpels surrounded by accessory tissue. (link)

Some fruits (in the botanical sense) similar to stone fruits are neither drupes nor pomes: the avocado, for example, is a large berry (in the botanical sense) with a single large seed.

As in the case of stone fruit, for both nut and (now, as must be obvious) berry, botanists have taken over ordinary vocabulary and employed it as technical vocabulary in specialized senses. I understand some botanists’ reluctance to insist on fresh technical terminology (with its strangeness), but the strategy of repurposing ordinary vocabulary for scientific purposes sows considerable confusion. (An avocado is botanically a fruit, but *not* a stone fruit.)

On nut:

A nut is a fruit composed of a hard shell and a seed, where the hard-shelled fruit does not open to release the seed (indehiscent). So, while, in a culinary context, a wide variety of dried seeds are often called nuts, in a botanical context, only ones that include the indehiscent fruit are considered true nuts [“true X” indicates a claim that the technical, botanical, classification and terminology is the only true one]. The translation of “nut” in certain languages frequently requires paraphrases as the [word] is ambiguous.

Most seeds come from fruits that naturally free themselves from the shell, unlike nuts [in the botanical sense] such as hazelnuts, chestnuts, and acorns, which have hard shell walls and originate from a compound ovary. Culinary usage of the term is less restrictive, and some nuts as defined in food preparation, like pistachios and Brazil nuts, are not nuts in a botanical sense. Common usage of the term often refers to any hard-walled, edible kernel as a nut.

Bewildered yet? On to berry, which is possibly even worse than nut:

The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors. The seeds are usually embedded in the flesh of the ovary (there are some non-fleshy exceptions, such as peppers).

In everyday English, “berry” is a term for any small edible fruit [in the everyday sense of fruit]. These “berries” are usually juicy, round or semi-oblong, brightly coloured, sweet or sour, and do not have a stone or pit, although many seeds may be present. [And grapes are certainly not berries in the everyday sense.]

Some edible berries (in the botanical sense): avocado, blueberry, cranberry, currant, gooseberry, grape, lingonberry, pepper, persimmon, pumpkin, tomato, watermelon; citrus fruits are berries with a thick rind and a very juicy interior. Some drupes (bayberry) and pomes (hawberry) are commonly referred to as berries. Then there are aggregate fruits (like blackberries and raspberries), which contain seeds from different ovaries of a single flower and so are not berries in the botanical sense. And there are multiple fruits, which include the fruits of multiple flowers that are merged or packed closely together: mulberries, for example (not berries in the botanical sense). And in accessory fruits, the edible part is not generated by the ovary; in the strawberry, for example, the aggregate of seed-like achenes on the outside is actually the fruit (in the botanical sense), derived from an aggregate of ovaries, and the fleshy part develops from the receptacle (again, not a berry in the botanical sense).

Some berries in the botanical sense are berries in the everyday, culinary, sense (blueberries, cranberries, currants, gooseberries, lingonberries) and a number of these have -berry in their common names, but the fit between the botanical and the everyday usage is poor indeed: lots and lots of things that are botanically berries aren’t referred to as berries in ordinary usage, and lots of things that are referred to as berries in ordinary usage aren’t berries in the botanical sense.  (As a result, most berry pies and berry jams are made from things that aren’t berries in the botanical sense.)


4 Responses to “Stone fruits, nuts, and berries”

  1. arnold zwicky Says:

    From Rod Williams on Facebook:

    Rod Williams Re almonds… you’re just not going to the right farmers’ markets!

    Green Almonds | The Hungry Mouse
    Learn about green almonds, how to clean them, and what to do with them in the kitchen.

  2. the ridger Says:

    Makes the whole “is the tomato a fruit or a vegetable” brouhaha seem tame!

  3. NuttyBuddies and Nutty Buddies | Arnold Zwicky's Blog Says:

    […] looking up the botanical term nut, I was taken to the page for the NuttyBuddy, a piece of protective athletic gear for men, combining […]

  4. tree nuts | Arnold Zwicky's Blog Says:

    […] complexity here, let me take you back to nut as a botanical (technical) term. From my “stone fruits, nuts, and berries” […]

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