Wednesday, November 30, 2011

Fruits and Vegetables

You may be privy to recent internet outrage over Congress declaring pizza a vegetable. In reality, Congress blocked a US Department of Agriculture proposal to increase the amount of tomato paste necessary to qualify as a school-lunch vegetable – for the past 20 years, two tablespoons has been sufficient.

Yet, to some, the true display of ignorance is calling tomato a vegetable, for – as even the most casual one-upper knows – they are really fruits. Which brings us to today’s post.

In culinary usage, fruits are fleshy, seedy, sweet, plant structures that can be eaten raw. Seed-associated structures outside these criteria might be categorized as nuts, pods, cones, or vegetables. Vegetables also include leaves (spinach), stems of leaves (celery), stem shoots (asparagus), buds (Brussels sprouts), and flower buds (broccoli). Bulbs (onions), tubers (potatoes), and roots (carrots) also fall into this category.

The trouble begins when you compare the culinary and scientific definitions of fruit. According to botanists, a fruit is any seed-containing structure derived from one or more flower ovaries. The simplest category of fruit is… well… simple fruits – meaning they mature from a single plant ovary. Dry simple fruits lack the sweet, soft flesh associated with culinary fruits, and include wheat, peas, and acorns. More familiar fleshy simple fruits include stone fruits or drupes (plums and cherries), and berries.

You’ve more than likely heard the word “berry” before, but its botanical definition may surprise you. Although blueberries and cranberries are true berries, grapes, tomatoes, eggplants, and chili peppers also make the cut. Additionally, there are two types of modified berries. Hesperidia have thick rinds and juicy interiors (citrus fruits like lemons, oranges, and kumquats) and pepos – like pumpkins, cucumbers, and melons – have hardened skins.

Many fruits we traditionally call “berries” are actually aggregate fruits – they develop from multiple ovaries of one flower; each small sphere – or drupelet – of a raspberry, blackberry, or boysenberry develops from a separate ovary. Similarly, multiple fruits develop from the ovaries of many flowers: examples include pineapples, figs, and mulberries.

Finally, accessory fruits derive some of their flesh from tissues adjacent to the ovary. For example, the carpels (structure surrounding the ovary) of pomes (apples and pears) become part of the fruit, forming a tougher “core” around the seeds. Likewise, the flesh of a strawberry develops completely from ovary casings; the achene – commonly referred to as “seeds,” though they are truly dry simple fruits – develop from the ovaries themselves.

So, yes: scientifically, tomatoes (and cucumbers, chili peppers, corn kernels, and eggplants) are fruits. Then again, scientifically, nothing is a vegetable, as vegetable is a purely culinary term for edible plant parts. So here are your options, tomatoes-are-fruiters: either get a lot more obnoxious about policing plant-based language, or accept that in a world as rich and complex as our own, words can have more than one meaning.

Source: 1, 2, 3, 4, 5