Thursday, June 7, 2012

Sun, Sand and Orchids

Today's Guardian Country Diary describes a recent visit to the seaside at Cleethorpes. If you walk on past the pier with all its attractions, at the far end of the promenade, beyond the leisure centre and just under the sea wall near the miniature railway, you'll reach Cleethorpes Local Nature reserve

It's a long expanse of sand dunes, between the sea wall and the saltmarsh on the edge of the river Humber, and it hosts a fabulous display of southern marsh orchids that were in full bloom at the end of May.

There are some magnificent specimens that....

.... are packed together so densely in places that you need to be very careful where you put your feet.

While we were there I repeated Darwin's experiment for extracting the pollinia from an orchid flower, described in his book Fertilisation of Orchids, which I described in a recent post on early purple orchids. The pollinia are whole stamens that butterflies carry away in their entirety when they poke their proboscis into a nectar spur at the rear of the individual orchid flower. Darwin described how you could extract a pollinium, which is sticky at its base, by poking a sharp pencil point into the nectar spur. The paired pollinia are located where those two dark club-shaped structures are in the hood of the flower.

I didn't have a pencil so I poked this fine twig in instead - and out it came with a pollinium attached.

Darwin actually counted and calculated the number of pollen grains in one of these pollinia: there are enough to fertilise over 120,000 seeds. The survival chances of these tiny wind-born seeds, which you can see by clicking here, are minute.

1 comment:

  1. It a long time since I explored the salt marshes and creeks between Cleethorpes and Mablethorpe. Orchids seem to be well adapted for what might really be thought of as poor growing conditions.