Monday, August 24, 2009

Crane'sbill Catapults

Meadow Crane'sbill catapults discharged
Meadow Crane'sbill catapults primed and ready to go

The meadow crane’sbill Geranium pratense in my garden (see http://cabinetofcuriosities-greenfingers.blogspot.com/search/label/Geranium%20pratense) has now run to seed and is using its natural catapult mechanism to hurl seeds around the flower borders. There are five seeds, each inside an ovary that splits open, arranged around the bottom of the central ‘beak’ of the fruit and connected to it by long strips of dead cells that become tensioned like springs as they dry out. When the tension reaches a critical point each ovary breaks free and is flicked upwards violently by its ‘spring’, hurling out the seed – just like a rock launched from a Roman siege catapult. It’s a highly effective mechanism – from one original plant, I now have meadow crane’sbills all over the garden. The seeds of this species have a hard, water-repellent outer coat and are slow to germinate, so if you want to raise it from seed gently abrade the seed coat with a piece of sandpaper, then it will germinate very quickly.

4 comments:

  1. You never cease to fascinate and amaze, thanks.

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  2. Thanks Adrian, nature never ceases to fascinate and amaze me too

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  3. Thanks Keith, it was a bit of a damp day when I photographed these - if it had been drier the 'springs' would have curled back even further. A perfect fruit, when it's fired all its seeds, looks like a minaiture candelabra.

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