This waterlily is starting to outgrow the garden pond.  Rooted in the mud at the bottom, in about 5ft (I.5m) of water, the plant sends out a succession of new leaves throughout the summer, overlaying leaves already covering the surface of the water.  If most of the surface of a leaf is covered it starts to turn yellow and decay.  Rotted leaves sink to the bottom and feed new growth, but this plant is already strong enough, so I remove the old leaves if I can reach them.  As the circular pond, designed with wildlife in mind, is over 8ft in diameter (nearly 2.5m) and half the margin is surrounded by waterside plants, my tidying impulses are kept in check.

 

Walney nymph

 

The emerging waterlily leaves are well adapted to pushing their way through crowded vegetation, remaining tightly rolled until they are clear of obstructions and can flop back onto the surface of the water.  Leaves left standing above the water provide a convenient launch pad for dragonfly nymphs ready to shed their final larval skin and to emerge as winged adults. There’s a nymph, or rather an empty skin, on the leaf at the right of this picture.

I’ve seen nymphs crawling on plants below the surface, found empty skins and seen a newly hatched dragonfly drying its wings but I’ve never seen the process in action.  I noticed this ‘nymph’ this morning and kept an eye on it for a while but finally realised it was just another exuvia or cast skin.  There’s a great sequence of photos on the website of the British Dragonfly Society, showing how the new adult extracts itself from a small hole in the thorax, leaving the skin attached to the plant.   It seems an unnecessarily awkward process but leaving an empty skin to fool passing observers may have an evolutionary advantage.  By the time a hungry bird has tried a few tempting skins and found them empty it may give up on emerging dragonflies as a source of food, sparing the one that’s just crawled out of the pond behind it.