Fruit? Vegetable? Berry? Legume?
First of all, let me make it known that I am NOT writing this article from the perspective of an expert trying to disseminate knowledge; but rather as a layperson in the process of learning.
There is a lot of confusion over what constitutes a fruit or vegetable, and that confusion is only amplified when you start throwing around other terms like ‘berry’, ‘legume’, or ‘drupe’. I am interested in growing potatoes for the first time this summer, so I have been doing some research on the best growing methods. I quickly learned that potatoes are not what I thought they were. Are they a root? Are roots vegetables? And then I ran across an article about a potato fruit! I was beginning to get confused, so I decided to go back and refresh my memory on what makes a vegetable a vegetable or a fruit a fruit.
Botanical vs. Culinary vs. Legal Definitions
Image Credit: Hopefully acceptable username at English Wikipedia [Public domain]
Did you know that scientists use a different definition for fruits and vegetables than chefs? I sure didn’t! How did something so seemingly simple become so convoluted?
Botanical Definitions
From a botanist’s perspective, a fruit is defined as the seed-bearing structure in angiosperms formed from the ovary after flowering. Any other part of a plant, botanically speaking, would be considered a vegetable. Sounds simple enough, right? Well, as you’ll see if you continue reading, it’s really not. But, before we get to the confusing stuff, let’s talk food and politics for a moment.Culinary Definitions
Thanks to some cantankerous cooks, many things that would be called a fruit in the field are considered to be a veggie in the kitchen, or vice versa. For them, it all boils down to flavor. If it tastes sweet, it is considered a fruit; if it is savory, it is a vegetable. By this definition, rhubarb - a sweet tasting celery-like stalk of a plant - would be a fruit. On the other hand, a jalapeno pepper - a seed containing swollen ovary - would be a vegetable. And, in the US, the government tends to agree!Image Credit: Tomatoes by The Ewan
Legal Definitions
You see, buying and selling fruits and veggies is big business. And, anything that involves money attracts government regulators much like blood in the water attracts sharks. The late 1800s saw the US placing large tariffs on many foreign imports. While these tariffs were generally popular among those involved in manufacturing, they were quite unpopular with American farmers who were able to produce base products like corn, rice, and cotton at cheaper prices than foreign competitors. For them, the tariffs were inhibiting their ability to sell their crops. So, one side wanted to get rid of the tariffs while the other wanted them to remain in place.Blah, Blah, Blah… Politics
President Chester A. Arthur signed into law the Tariff of 1883. This crappy piece of legislation did little to appease people on either side of the aisle. They basically raised tariffs on some goods while lowering them on others. The overall effect was an average decrease of 1.47 percent (according to Wikipedia). What the legislation did do, however, was exempt fruit imports from the tariff.
Enter importer/exporter Art Vandelay John Nix. In 1886, Nix imported a load of tomatoes - a fruit by botanical definition - from the West Indies. When he was charged a vegetable tariff at port, Nix raised a ruckus but ended up paying the duty under protest. He went on to sue the collector of the port of New York over the tax. The case eventually made its way to the Supreme Court where, in a decision totally NOT driven by money, court justices unanimously agreed that tomatoes should be considered a vegetable for the purposes of tariffs. Because, you know, people generally eat them as a part of the main course rather than desert. No, seriously… that was the rationalization:
Botanically speaking, tomatoes are the fruit of a vine, just as are cucumbers, squashes, beans, and peas. But in the common language of the people, whether sellers or consumers of provisions, all these are vegetables which are grown in kitchen gardens, and which, whether eaten cooked or raw, are, like potatoes, carrots, parsnips, turnips, beets, cauliflower, cabbage, celery, and lettuce, usually served at dinner in, with, or after the soup, fish, or meats which constitute the principal part of the repast, and not, like fruits generally, as dessert.
-Supreme Court Justice Horace Gray
I guess that is why the tomato is both the official state fruit and vegetable of my home state of Arkansas; a fact that has confused poor little 5th graders for decades.
Now, The Confusing Part
Well, the part about vegetables is pretty straight forward: if it ain’t a swollen flower ovary, it’s a veggie according to botany. So, my potatoes, while not root structures, but rather specialized stem structures called tubers, are still vegetables. However, fruits get a little fruity!Anatomy Of A Fruit
As we will discuss, the anatomy of a fruit can vary wildly from one type to another, but they are all made up of the same basic layers derived from the carpel(s). Since carpels are modified leaves, they are made up of three basic layers: an upper epidermis and a lower epidermis with a mesophyll layer in between.Image Credit
The exocarp is the outermost layer of the fruit. It is derived from the lower epidermis of the carpel. If we’re looking at a peach or a cucumber, the exocarp would be what we refer to as ‘the peel’. If we’re looking at an orange, the exocarp would the the outermost orange colored layer of ‘the peel’; the part we get our orange zest from.
The mesocarp is the middle layer found just underneath the exocarp. It is derived from the mesophyll layer of the carpel. In a peach, the mesocarp would be the part that we eat. In our orange, it would be the tough white layer just beneath the exocarp.
The endocarp is the part that directly surrounds the seeds. It is derived from the upper epidermis layer of the carpel. The endocarp varies wildly from one type of fruit to another.
In fleshy fruits, the exocarp, mesocarp, and endocarp make up the pericarp.
Additionally, some fruits, like the apple, may have additional layers formed by other parts of the flower.
Comparing Apples To Oranges
There are several different categories of fruit. Identifying them requires a knowledge of how many flowers go into making a fruit, which parts of those flowers become a part of the fruit, and what structures of the fruit those flower parts become. I’m going to see if I can piece them all together in some sort of coherent fashion. If I get something incorrect or over simplify, please let me know in the comments.So, different fruits can fall under any one of three umbrella categories: simple fruit, aggregate fruit, or multiple fruit. From there, those categories can be broken down into sub categories and sub sub categories.
Simple Fruit
Simple Fleshy Fruit
Imagine a piece of fruit, right now. Odds are that what you envisioned was an example of a fleshy fruit. Fleshy fruits are the ones where some portion of the pericarp (often times, the mesocarp) has become enlarged. If that fruit was derived from a single ovary, it would be considered a simple fleshy fruit. Examples include grapes, tomatoes, cucumbers, and citrus. Additionally, simple fleshy fruits can be broken down into 5 smaller groups:Image Credit: Grapes by tribp
Berries
To start off, many of the things that we call berries are not berries at all… botanically speaking. Things like blackberries and strawberries don’t make the cut. Furthermore, there are some fruits that are considered berries that many of us consider to be vegetables! Berries are simple fruits (so, they come from a single ovary) in which the ovary wall of the carpel(s) become fleshy when the fruit matures.Examples of berries include blueberries, grapes, tomatoes, bananas, and avocados. [Some sources] even include cucumbers in the berry category, although most of the information I found considered them to be a pepo.
A berry may be made up of more than one carpel. If you look at a cross section of a tomato, for example, you will notice several cavities full of gushy seeds separated by a fleshy partition. Each one of those cavities comes from a single carpel. Different varieties of tomato flowers contain varying numbers of carpels, but you can determine how many the flower had by counting the cavities in the fruit.
Image Credit: Ekko at Wikimedia Commons and Juan de Vojníkov at English Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/)]
Hesperidium
Hesperidium fruits are always covered with a leathery rind, and the fleshy part of the pericarp will have partitions. Some sources consider them to be a special category of berry; and, like berries, you can determine the number of carpels on the flower by counting the segments in the fruit. An orange is a great example of a hesperidium type of fruit. The juicy flesh that we eat consists of lots of tiny juice sacs that formed from little hair-like structures called trichomes.Image Credit: Veganbaking.net from USA) [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)]
Pepo
Pepo fruits belong mainly to the gourd family. They include things like cucumbers, pumpkins, and watermelons and they are characterized by a tough outer flesh. Do note that several sources I found left off the pepo fruit type and instead included them as berries.Image Credit: Cherry-o by d3adcrab
Drupe
A drupe generally has a soft, thin exocarp layer and a fleshy mesocarp, but the endocarp will form a stone-like pit structure that houses a single seed. A perfect example of a drupe is a peach. Peaches have soft, thin peels and a juicy flesh that we eat. However, what many of us consider to be the peach seed (the pit) isn’t actually the seed, but rather, it contains the seed. Other examples of drupes include plums, coconuts, and even pecans, walnuts, and almonds.Image Credit: Apple a day by Patrick McFall
Pome
A pome is what is known as an accessory fruit, because, in addition to having structures derived from the carpels, it also has parts that come from other parts of the flower, like the sepals or petals. An apple is a good example of a pome. The fleshy part that you eat, the pulp, is actually made of the flower’s receptacle. The true fruit (the part derived from the flower’s ovary) is the part that we call the core.Simple Dry Dehiscent Fruit
These are fruits that are derived from a single ovary (simple), but they do not have a fleshy pericarp (dry). Dehiscent means that the fruit naturally cracks open to release its seeds once it has fully matured. Simple dry dehiscent fruit can fall under one of several different categories.
Image Credit: Organic whole in-shell peanuts on white background by Marco Verch
Legumes
You’ve heard of them. You may even be able to name off a few examples. But, do you know what makes a legume a legume?Legumes are simple dry dehiscent fruits that split along two lines to release their seeds. They form from a single simple ovary made of a single carpel with two rows of ovules; the egg cells that are fertilized during pollination to become seeds. Examples include beans, peas, and peanuts. The pod is the fruit. At maturity the pod dries out and splits vertically along both sides, allowing the seeds to fall out. Furthermore, if you’ve ever opened up a bean or pea pod, you may have noticed that there were seeds attached to each side of the pod. That is because the seeds on one pod formed from one row of ovules, and the seeds on the other pod came from the other.
Image Credit: Sweetgum Balls by Marvin Smith
Capsule
Capsules are dry dehiscent fruits that form from single ovaries that had more than one carpel. If you want to, you can break this group down into even more specific sub-types of capsules, but this post is already getting too long, so I’m going to let you research that on your own. Some common examples of simple dry dehiscent capsules include lillies and sweet gum balls.Image Credit: Peony Seeds by Margo Akermark
Follicle
Follicles are dry dehiscent fruits that split lengthwise on one side. Examples of plants that produce this type of fruit include milkweed and peony.Simple Dry Indehiscent Fruit
Image Credit: Kaldari [Public domain]
Achene
In an achene, the ovary of the flower dries to form the outer portion of the fruit that we might commonly refer to as the ‘shell’. The seed is attached at a single point on the inside of the ovary. Examples of achenes include sunflowers, dandelions, and the true fruit part of a strawberry (we’ll talk about that in a second).Image Credit: Wheat close up 5 by Wheat initiative
Grain
A grain also contains an outer hull derived from the ovary of the flower, but the seed that it contains is attached at all points to the inside wall. You usually find grain-type fruits formed by grasses. Examples include wheat, rice, and corn.Image Source: Red maple, seeds_2013-04-11-15.11.33 ZS PMax by USGS Bee Inventory and Monitoring Lab
Samara
Samara usually consist of a single seed with a paper-like attachment designed to catch wind. The paper-like wing is derived from the ovary wall. Those little helicopter thingies that fall from maple trees are great examples of a samara.Image Credit: Acorn Autumn by Christoph Rupprecht
Nut
A nut is basically a large-sized hardened achene. It generally consists of a seed that is surrounded by a coat formed from the ovary of the flower. Some nuts, such as the brazil nut or acorn, only form a hard outer shell made up of the entire ovary wall. Others, like the pecan, have a hard outer shell that is formed by the inner ovary wall and a softer ‘husk’ formed by the outer ovary wall.Aggregate Fruits
Image Credit: 200907011 Blackberries 075 by cygnus921
An example of a true aggregate fruit is a blackberry. In a blackberry, each of those tiny, juice-filled sacs is actually a drupe (or drupelet) containing a single seed. A single blackberry flower contains numerous carpels, and each of those drupelets formed from a single carpel. So, that blackberry formed from a cluster of pollinated carpels, all of which are stuck onto the receptacle of the flower.
Image Credit
An example of an accessory aggregate fruit would be a strawberry. I would be willing to bet that when you eat a strawberry, your least favorite part is the fruit. The sweet, juicy, red part that we all love is actually made from the enlarged receptacle of the flower. The actual fruit are the tiny yellow things on the outside that we generally refer to as ‘seeds’. Each one of those is a tiny achene-type fruit.
Image Credit: Pineapple Landscape by ECohen
Multiple Fruit
Finally, we have multiple fruits. In every one of the fruits that we have discussed so far, each fruit has come from a single flower. Even in aggregate fruits, the cluster came from a single flower that happened to have had multiple carpels.Multiple fruits occur when many different flowers congregate together to form one big fruity mass. Examples include pineapples and mullberries. In both examples, each individual fruit can be distinguished by looking at the outside of the mass. Each individual fruit also shows remnants of the parts of the flower that made it.