Sunday, May 1, 2016

Botany for Hikers: Flower Symmetry

When learning how to identify plants by family, I used a book called California Plant Families. It had this fabulous key that was kind of like a Choose Your Own Adventure book. You know, "Does the flower have this trait? If yes, go to #6. If no, go to #30." That kind of thing. Ultimately you narrow it down to one or two plant families, and then you can figure out what you're looking at.

One question has to do with the shape of the flower. Is the flower radial? Radial flowers are what you might think of as "typical." Like, when you ask a 5 year old to draw you a flower, it's the shape that they will draw. A center with petals sticking out on all sides, basically in a circle. These flowers are radial:


So are tulips, lilies, daffodils, and daisies.

These flowers, the namesake of this blog, are not radial:


The flower above is Gill-Over-the-Ground, a common (edible) lawn weed in the mint family. While not radial, they are, however, symmetrical. If you drew a vertical line through the flower and divided it in half, the halves would be identical. If the two halves looked different, then the flower would be asymmetrical.

Like all flowers in the Mint family, this flower has two fused petals on top, and three fused petals on the bottom. The flowers are organized in a whorl on the stem. That is, at a single location on the stem there are three or more flowers sticking out in different directions. Typically, but not always, mint family flowers are in punctuated whorls, which is what you see here. So there's a whorl, then a space with just stem, then another whorl. Mint, catnip, rosemary, lavender, horehound, and sage are all in the Mint family, so it should be pretty easy to find one whether on the trail or in an herb garden to observe that the flowers look similar to these ones here.

That's getting ahead of ourselves, but it's a bit of a preview of what's to come. That is, that once you know basic plant and flower terminology, you can start to learn the traits of different plant families, and then you can easily spot a flower you've never seen before in your life and easily say "That's in the Rose family!" (People who are much savvier than me can look at an unfamiliar plant and narrow it down to the genus. I'm not that good. Thank goodness for plant guidebooks.)

To review:




Wild Peas
Symmetrical, not radial

Nuttall's Snapdragon
Symmetrical, not radial

Bush Poppy

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