Friday, October 3, 2008

Plant Anatomy 101: Strawberries

The thing about having two blogs (one for work, and one where I feel I can express myself a little more freely) is that there are some things that I do for one that completely applies to the other, and vice versa. So when I posted the potato-blog the other day, my boss wanted me to put it up on my work blog. I'm not sure what the etiquette is on getting double-duty on a post, but I guess that's just the way it's going to have to be. So with out further ado, I'm double-posting again for plant anatomy 101, only substitute potatoes with strawberries. (This post originally appeared on Green Fork Utah.)

Plant Anatomy 101: Strawberries

Have you ever wondered why strawberries have their seeds on the outside of their fruits? When I worked at Red Butte Garden, this was a point that we brought up frequently with the first graders. We mostly just pointed this fact out and never really talked about why, other than a quick suggestion of possible seed-distribution benefits. Well today I was thinking about strawberries for whatever reason, and now I want to share what I've discovered!

As we learned in the potato post, there is a big difference between what botanists classify as fruit and what we regular ol' plant eating people define as fruit. Here I will be talking about strawberries as defined by the botanists. Let's back up a second: a true fruit is a fruit from which all tissues are derived from a ripened ovary and its contents. Simple fruits, such as oranges, develop from a single pistil and are true fruits. True berries are also simple and true fruits in that they develop from one ovary. Blueberries, cranberries, grapes, tomatoes, and even bananas fall into this category. It seems that there are a lot of definitions for basically the same thing.

Strawberries, on the other hand, are not true fruits. They are called aggregate fruits which means that the strawberry is formed through many ovaries ripening. The "seeds" on the outside of the strawberry are actually individual little "fruits" that have ripened in their own separate ovaries. These little "seeds" are called achenes (ah-keens) and inside each achene is a little seed. Sunflower seeds are also achenes where the hard shell is the outside of the fruit and the seed is inside the hard shell. Since an aggregate fruit forms from many ovaries, it is also known as a complex fruit. Other complex fruits include blackberries, raspberries, and mulberries. These fruits however, because they lack achenes, are not aggregate fruits.

But what about the bight fleshy part of the strawberry that we eat? Strawberries are not only aggregate, complex fruits with achenes, they are also accessory fruits. Accessory fruits are fruits that contain a significant amount of other tissue in addition to the ripened ovary and mature seeds. Apples and pineapples are accessory fruits. In the case of the strawberry, the extra tissue that we are consuming is the enlarged end of the flower's stamen. Because of this, strawberries must be picked at full ripeness, otherwise they wont ripen after they have been picked.

Random strawberry factoids:
  • Until the mid-nineteenth century, strawberries were considered poisonous in Argentina.
  • Native Americans had already been cultivating strawberries when European colonists arrived. They would crush the berries and bake them into cornmeal. Colonists adapted this practice and made it their own by making the first strawberry shortcakes.
  • Medieval stone masons carved strawberry designs on altars and on the tops of columns to symbolize perfection and righteousness.
  • In Ancient Rome, the strawberry was the symbol for Venus, the God of Love.
Who knew that strawberries were so complex and had such rich histories!

Strawberries Photo Credit

1 comment:

Allan Stellar said...

I've been reading through your blog. Good work! Very enjoyable. I'll be back...