Tuesday, May 28, 2019

Springtails

Lately, after heavy overnight rain, any containers in the garden that can hold water have hundreds, and sometimes thousands, of springtails floating on the surface film by daybreak. It seems likely that they were feeding and breeding on organic matter and probably fungi in the bottom of the containers when they had dried out, then have become marooned on the rising water. 

They float in rafts of up to one thousand individuals. I think there is more than one species involved, but I'm struggling to identify them with certainty. 

The two movies at the bottom of this post show just how active they are, many of them using their furcula under their tail to leap into the air.












Saturday, May 25, 2019

Milk thistle

A few days ago I had a call from a landowner who had unusual, unidentified thistles flowering on the edge of one of their fields. They turned out to be two milk thistles Silybum marianum, easily identifiable by the white variegated veins on their leaves. They are about five feet tall and are native to southern Europe, but have been introduced to many countries. They turn up sporadically in Britin, usually on waste ground, though rarely up here in County Durham. 

The plants are painfully prickly, along the leaf margins and especially on the tip of the bracts that surround the flowers. Milk thistles are biennials and it looks like this is now a small, self-sustaining population. Seeds might have arrived originally in animal feed.

I was first shown one here a couple of years ago, but then it was late in the season and all the flowers had run to seed (see bottom photo). This is the first time I've seen it in flower.




























Sunday, January 6, 2019

Collared earthstars in Durham

I need to thank my former colleague Professor Stephen Willis, in the Biosciences department at Durham University, for giving me the location of these collared earthstars Geastrum triplex. I had never seen an earthstar before today and never expected to see them in Country Durham, where they are rarities.

These were growing under an ash tree.






















Earthstars have a similar method of raindrop-impact spore dispersal to puff-balls, although it seems that they are not closely related. When raindrops fall on the thin inner coat (endoperidium) the impact sends a puff of spore-laden air out of the pore and into the air stream. Before this can happen the thick outer coat (exoperidium) splits into segments and bends outwards and backwards, forming a star-shaped collar that raises the whole fungus higher into the air stream - a particularly valuable attribute when it is growing amongst a ground layer of ivy, as it was in this case. Once they are no longer attached to the soil they can also blow across the ground on windy days, shedding spores as they go.