Wednesday, May 19, 2010

Dandelions (Taraxacum species)

Dandelions flower all year, but the main flush is towards the end of April: this is the time when you notice those golden-yellow riots on verges, roundabouts and over-rich pasture. (I remember reading somewhere that St. George's Day, April 23, is the traditional day for making dandelion wine.)

The flower-heads have two moments when they appear perfect, the first being when the flower opens dazzlingly to the sun, and the second (a couple of weeks later) being the clock, that wonderful hazy globe.

But one thing I'd never really thought about before was how do you get from one to the other? The "petals" - florets I suppose I mean - have completely disappeared. So what happens to them?

It turns out to be quite a complicated process. First the flower closes up, so it looks like a cartridge surrounded by the inner bracts. The petals start to shrink and twist and wither, becoming stuck together like the rippled pages of a damp book. Initially the florets are attached to the capitulum, but as the achenes below extrude their feathery pappi, the upward pressure detaches the matted florets from the capitulum and pushes them out of the top of the cartridge-case. There they dry out and eventually fall off as a single pellet, like ash off a tailor-made. A day or so later, the bracts bend outwards and then reflex, opening the clock.

No wonder we usually miss that inconspicuous pellet when it goes to ground among the tangle of leaves and small debris of the soil surface. This one, happily, was left hanging in suspension by a blade of grass that got caught in the works.

And, nothing in nature being really perfect, it sometimes happens that the mechanism doesn't quite fire...



At 11:12 am, Blogger Vincent said...

I love your post. An excellent match of words and images to make an informative whole, all the more precious for its revelations about one of the most common and neglected plants, perhaps one which a gardener views with dismay and a non-gardening passer-by enjoys without thinking about it too much. I've seen all the stages separately but never considered their wonderful strangeness as a linked-up narrative before. There was an impact, and an unanswered question, similar to when I read about the Burgess Shale, in a book by Steven Jay Gould. Wonderful Life, I think it was called. My question was "why is evolution so strange?"

This morning in the backyard I saw that my Lunaria (Honesty) blossoms have already shed some of their petals, and I've been able to see how their full-moon-like seed pods develop, first spear-shaped, then wide in the middle like Zulu shields, then plumped out to their mature shape. I'd gathered the seeds from waste land, but alongside them are Physalis alkekengi (Chinese Lanterns), now spreading all over from a little plant I bought two years ago. Inspired by your post, I want to check all the stages from budding to full development of the orange lantern.


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