Black spleenwort

On the whole today's been OK. Our old car went in for a service and MOT, and only had to have two light bulbs replaced! It can now stay with us for another few months...

As the weather was dire Pete and I went into Peterborough to sort out post-Christmas finances. But Peterborough seemed broken. Our usual car-park was shut for renovation, part of the bus-station was closed causing traffic chaos on the road next to the temporary bus parking areas, and when we got to the bank we found it was also closed because all their computer systems had crashed. But being forced to park in one of the other multi-storey car-parks brought a pleasant surprise. A sloping shaded concrete wall, open to the elements, had quite a few ferns sprouting from it, including heaps of hart's-tongue, a few tufts of wall-rue and quite a few plants of black spleenwort.

Those of you who live in the damp west probably have heaps of similar ferns around, but in the east these species are pretty rare. The natural habitats of wall rue and black spleenwort are limestone rocks, but they are also quite happy on brick mortar and concrete. In the east there are few permanently moist and shaded places where they can grow. Railway bridges were always promising places to hunt, but many of these are being dismantled for safety reasons. It's good to see them settled in the city centre, brightening up a rather dank corner. I just hope they don't get 'tidied'!

My photograph is a close up of the back of the frond. Ferns have a complicated reproductive cycle. The adult sporophytes produce sporangia (the wiggly brown structures) in this case housed in a linear indusium, which splits when the spores are ripe. The sporangia will soon explode releasing haploid spores which then drift on the wind and germinate to produce a tiny gametophyte or prothallus. These produces gametes (often both sperm and eggs on the same prothallus) . A mobile, flagellate sperm fertilizes an egg that remains attached to the prothallus. The fertilized egg is now a diploid zygote and grows by mitosis into a diploid sporophyte (the typical "fern" plant).

I hope you're all still awake!