Birch Polypore

A very typical looking Birch Polypore conk photographed a few days ago in the Forest of Preuilly.

Birch Polypore Fomitopsis betulina (Fr. Polypore du bouleau) is one of the many fungi that feeds off wood. Like other polypores it forms a fleshy leathery 'horse's hoof' fruiting body known as a conk. The upper surface can be white, brown or grey and is a bit suede like. The underside has fine pores with white spores. The flesh is white. It only attacks birch trees, almost always those which are old or already weakened. If you see a bracket fungus on a birch tree here it will very likely be Fomitopsis betulina. The birch trees that are attacked may have been stressed by a loss of light as other trees grow up around them, or by drought or fire. The fruiting bodies can appear singly or in groups. Nevertheless the Birch Polypore is unlikely to kill the tree very quickly, if at all ultimately. This species is much less aggressive than other polypores, but like them, it causes white rot.

 

The underside of a large conk which I found on the ground several days after first photographing it. The birch tree host had been blown over by the wind.

The fruiting body can be up to 20 cm across and 6 cm thick. It smells and tastes a bit sour. You can safely do a taste and spit test as the mushroom is not toxic, but its cork like consistency means that it is not considered edible. Detached from the tree and held in the hand they are heavier than you would expect.

 

A series of Birch Polypore conks all the way up a dying birch trunk.

Like other polypore species it has been used by humans from prehistoric times up until the 20th century as a firelighter. It has also been used to treat parasitic intestinal worms, and has anti-inflammatory and antibiotic properties. Ötzi, the 5300 year old mummy found in an Alpine glacier, was carrying Birch Polypore, possibly for its medicinal properties.

Underside.

Finding Fluorescence

Simon bought me a UV torch for my birthday. It arrived a couple of weeks ago and we've been madly checking the firewood before putting it in the stove, and fungi and lichen in the forest when we walk. 

 

This unidentified fungus on a chestnut firewood log looks white under daylight but fluoresces turquoise under UV light.

UV torches are the latest toy for naturalists. They can be used for looking at flowers, insects, scorpions, lichens or animal eyeshine at night. They are useful for geologists too, as some minerals fluoresce.

Humans can't see ultra violet light, but lots of animals such as insects and birds can. Somewhat to my surprise there is a whole project in iNaturalist, the global biodiversity monitoring citizen science website, on UV fluorescent organisms. 

Simon had to do lots of research to make sure he bought the right product. The right frequency (365 nm) is important. 

Once it gets a bit warmer and less wet we'll have to set up some experiments in the garden at night.

Walking Around Chaumussay in Early Spring

On Friday 20 February Simon and I did a 2 kilometre circuit at Chaumussay. We wanted to check on the river water level of the Claise and the colony of wild daffodils that grows by the voie verte (greenway). The temperature was 12°C, there was no wind to speak of, and it wasn't raining. Since France has been experiencing the longest period of continuous rain since records began (36 days and counting) having an afternoon when it wasn't raining was noteworthy. The walk took us about half an hour.

 

The Claise is high but not unusually so for this time of year. Some riverside gardens and fields are flooded, but there is no real threat to life or property.

Silky Wall Feather Moss Homalothecium sericeum (Fr. Homalothécie soyeuse) on a low garden wall.

Grey Cushioned Grimmia moss Grimmia pulvinata on a low garden wall.

Colony of Wild Daffodil Narcissus pseudonarcissus (Fr. Narcisse jaune).

Primrose Primula vulgaris (Fr. Primavère acaule).

Lesser Celandine Ficaria verna (Fr. Ficaire fausse-renoncule), one of the most important sources of pollen for early emerging bees.

Cherry-plum Prunus cerasifera (Fr. Prunellier de Myrobolan) blossom, with a male non-biting midge from the Chironomidae family of flies. The larvae of these midges are known as blood worms (Fr. vers de vase).

European Ash Fraxinus exelsior (Fr. Frêne élevé) flowers.

Crocuses in a public garden.

Gilled Polypore

The Gilled Polypore Trametes betulina (Fr. Lenzite du bouleau) is rather an anomaly. It has recently been put in the genus Trametes. From above it looks like a Trametes, but underneath it has gills. No other Trametes species has gills, they have pores, and jolly handy it is for distinguishing Trametes bracket fungi from other similar genera, such as Stereum (which have smooth somewhat velvety undersides). Rather sadly the 'approved' English name has also been changed to the prosaic 'Gilled Polypore' from the romantic 'Birch Mazegill'.

The upper side is usually pale (white, cream and/or grey) but they can be brown, orange or red too. There can also be green from algae growing on the surface. The individual brackets are between 2 and 10 centimetres across and 2-3 centimetres deep. Growing directly from trunks or branches the fruiting body can usually only develop into a sort of half moon, not a full round. There are visible growth bands and quite a bit of somewhat bristly fuzz. The outer edge is rounded, not a contrasting colour and sometimes lobed. The brackets are quite thin, just a few millimetres. 

Underneath there are pale brown crowded irregular gills, with creamy white spores. The brackets are leathery, with white flesh if cut in half. 

This species is most often found on Birch, either living or dead, but it can also grow on Oak and Beech, and sometimes Alder and Hazel. It usually grows in groups, but can be a single isolated bracket. It is uncommon, but also possibly often disregarded because on first appearance it just looks like an old faded Turkey-tail T. versicolor, which is very abundant. If you don't turn it over, or identify the wood it is growing on as Birch, you will misidentify it.

The species is one of those which causes white rot. It is not toxic, but not worth eating.

Jelly Cakes

Jelly Cakes are, as far as I know, an old fashioned Australian speciality. A sort of pink raspberry flavoured alternative to the lamington (invented by a French chef in Australia -- see my previous blog post on the subject https://daysontheclaise.blogspot.com/2020/12/lamingtons.html).

 

Jelly Cake recipes are to be found in old Australian Women's Weekly or Country Women's Association (CWA) publications. Here is the one I used https://www.thecookingcollective.com.au/jelly-cakes/.

Jelly is not something French people understand or get on with in the way Australians do. Aussie jelly comes in packets of flavoured and sweetened crystals to be made up by adding water, so it mystifies British people too, who are used to a sort of gelled concentrate.

Anyway, a kind friend sent several packets of proper Aeroplane brand jelly crystals, so I made a trifle with one packet, and some jelly cakes with another. 

I filled my jelly cakes with whipped coconut cream, adding vanilla, sugar, whole raspberries and raspberry coulis. Coconut and raspberries is a nicer combination than dairy cream and raspberries in my opinion.

Further Reading: The story of Aeroplane Jelly on Wikipedia https://en.wikipedia.org/wiki/Aeroplane_Jelly.

Cherry Galls

 Cherry Galls (Fr. Galles-cerise du chêne) are caused on Oak trees by the tiny gall wasp Cynips quercusfolii. I've never seen the wasp, which is only 3 mm long, but I regularly encounter the galls on oak leaves in the forest.

The wasps develop on the oak trees, where they are responsable for the formation of spherical galls on the underside of leaves. 

This abundant gall was appears each year in two forms, one which reproduces sexually and one which reproduces asexually ie by parthenogenesis. In the summer, after mating, the female wasps lay their eggs on the oak leaves. Then their larvae develop in the galls on the underside of the leaves, a single 2 mm larva in each gall. The galls start off as yellow-green and transform into red-brown. 

 

Spangle and Cherry galls on oak leaves.

The adult parthenogenic female wasps emerge from the galls in winter, and in the spring they lay eggs on the new leaf buds on oak trees. A gall forms, but it is very different, being only a few millimetres across and covered in red filaments. The sexual wasps emerge from these galls in May and June. In the past it was believed that the parthenogenic and sexual wasps represented two different species.