Saturday, July 21, 2012

The Incredible Exploding Thistle

On a recent sunny afternoon, I noticed a mass of white gossamer fluff on the giant bull thistle that stands seven feet tall in one of the garden paths. It had not been there that morning. The mass consisted of spidery whorls of white threads, each carrying a tiny oval seed at the bottom. Some of the whorls -- "light as thistledown" because thistledown is exactly what they were -- were already lofting away on the breeze.

Uh oh.


I pulled out a handful of fluff, marveling at how neatly and densely the seeds were packed in -- dozens wedged into one small round seed pod about an inch across. No wonder the thing burst open.

In botanical circles there is a technical term for exploding plant parts: dehiscence.

I couldn't let this particular bull thistle go on exploding. There were enough seeds in one little pod and enough pods on a seven foot plant to eventually turn the whole yard into a thick thorny forest.

Already, the floating seeds were finding resting spots in quiet corners of the yard, ready to set up shop and bring forth new generations of towering bull thistles.

Before going after the plant with pruning shears and thick gloves, I took some final photos of the magnificent purple blossoms, full blown and feathery, or wilting, fading, and folding into themselves. Thistle blossoms are sought out avidly by bees and butterflies, and thistle honey, of course, is much prized. That's one reason I let the plant live out most of its span of time.

On YouTube I found an amazing video of a swallowtail butterfly feeding greedily from a thistle blossom for a full two minutes, in a scene I have never witnessed directly but fondly hope has occurred in our backyard and will occur again.

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