Mushroom of the Month - December 2009

This month's mushroom is an alien. Clathrus ruber looks alien and it doesn't really belong here, having arrived fairly recently, so experts believe. But here it is and it seems determined to stay; and, with the climate becoming ever more favourable to it, this mainly Mediterranean species is likely to be seen ever more frequently in the British Isles. Already it is fairly common in some southern parts of England (most particularly in the Westcountry and on the Isle of Wight) but also in southern Ireland too. In the Channel Islands these striking fungi are now very often a decorative feature of compost heaps and grassy orchards. That said, you can count yourself lucky if you do come across this remarkable relative of the stinkhorns... unless you happen to sit on one accidentally. If you think the common stinkhorn (Phallus impudicus) is smelly, save the superlatives for this rotter! For close-up photography a scuba outfit would be a good investment.

In much the same way that setting out to find giant puffballs is pretty much a futile quest (unless you already know a site where they occur), so seeking the cage fungus is also something best suited to masochists; these are fungi you just come across once in a (very long) while. The one pictured below was spotted in a shallow, leaf-litter filled ditch in the Serra around Monchique, in southern Portugal. They are not common there, but we did manage to find three in one day.

The half-buried 'eggs' from which the cage fungi emerge look very much like those of the common stinkhorn, but as the time nears for an almost explosive emergence the outer skin ruptures and the embryonic cage is clearly visible - see below.

The eggs are typically 3cm in diameter, but when fully expanded the cage is three times that size, with dark olive-green gleba coating the inner surface. Flies love them, of course, attracted to their stench of rotting meat, and the short-lived fruitbodies last just one or two days before collapsing and turning to mush.

Also known as the latticework fungus, Clathrus ruber occurs in summer and autumn, but with the heat emitted by rotting compost or wood chippings they can even be found in November unless the weather turns icy cold. Like us, they are not at all keen on frost.

If you know someone whose garden is infested with these amazing fungi, that's the place to go to see them... But take a clothes peg for your nose, and just be glad that it's not your garden!

There are more pictures and information about this mushroom (and its darker red relative Clathrus archeri) on www.first-nature.com/fungi - and we wish you much happy fungi foraying throughout the forthcoming festive season.