Oak Bracket, Pseudoinonotus dryadeus

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The last few days have seen a sudden change from a very warm and sunny late summer to a much cooler and rather rainy start to autumn. Flowers and insects are on the wane but fungi are starting to appear.

I was cycling near Carleton Rode, south-west of Norwich, a couple of weeks ago and passed an oak tree by the roadside with some distinctive bracket fungi growing at its base and stopped to take a look.

They were the Oak Bracket, Pseudoinonotus dryadeus. 

Oak Bracket, Pseudoinonotus dryadeus

Base of English Oak tree with Oak Brackets, Pseudoinonotus dryadeus

Oak Bracket, Pseudoinonotus dryadeus

Oak Bracket, Pseudoinonotus dryadeus

In its prime, the Oak Bracket is extremely beautiful. Its velvety upper surface is cream to rusty brown with a yellower margin and is pitted with tubes. These ooze an orange-brown liquid that looks like runny honey, though, as the First Nature website points out, “it is not as tasty as honey”. The fungus is not edible – it is described as bitter and tough.

Oak Bracket, Pseudoinonotus dryadeus

Oak Bracket, Pseudoinonotus dryadeus, oozing nicely.

The Oak Bracket is a parasite, mainly on species of oak, although Beech, Birch and Alder and Maple, Elm and Sweet Chestnut are occasional hosts. The fungus causes a white rot in base of the trunk (“butt rot”) and eventually branches can die off and the weakened base of the tree can make it prone to toppling. Spores enter through wounds in the tree’s bark so this is “one of many reasons not to damage tree bases with lawn mowers or other equipment“.

The Oak Bracket grows as an annual bracket without a stem. The ones I saw were in their prime; older specimens become corky and fibrous. The caps become blackened and cracked over winter, and sometimes persist for several years. They apparently smell very unpleasant. (The ones I found just smelt slightly mushroomy. I must go back and have a sniff when they’re older!) (See April 2022 update below.)

Oak Bracket is also known as Warted Oak Polypore, Weeping Polypore and Weeping Conk. The last two names refer to its habit of oozing liquid, but it’s worth knowing that other species of bracket fungus also weep. Two examples are Shaggy Bracket (Inonotus hispidus) , found especially on Ash and Apple trees, and Alder Bracket (Inonotus radiatus), found on Common Alder.

The Oak Bracket’s original scientific name was Boletus dryadeus and prior to 2001 the accepted name was Inonotus dryadeus, which is still used in some field guides (such as Sterry and Hughes) and on some websites (e.g. Wikipedia, Messiah University).

The First Nature website has some good pictures of the Oak Bracket. It also tells us generic name Pseudoinonotus comes from pseudo (false), ino (fibrous), ot (ear; also used in Otidea bufonia, the Toad’s Ear fungus) and –us (making it a Latinised noun). The specific name dryadeus means ‘found with or on oak trees’.

Pseudoinonotus dryadeus is commonest in the southern half of the British Isles. At the time of writing the NBN Atlas lists 292 records, with just three in Scotland. It also occurs elsewhere in temperate parts of Europe and in North America.

The Oak Bracket shouldn’t be confused with the Oak Polypore (Piptoporous quercinus), which is very rare in the British Isles and grows only on veteran oak trees (though there is apparently one old record on a Beech).

Cross section through a Crunchie

Cross section through a Crunchie bar.

When fresh Pseudoinonotus dryadeus also resembles a section through a Crunchie Bar but the taste, difference in size and presence of a chocolate coating on the latter should avoid confusion.

April 2022 Update

I did go back and sniff the Oak Bracket, in December 2021. The fruitbodies were now greyish black. There was no smell at a distance but if I sniffed the surface I could just detect  a not very pleasant nitrogenous smell of rotting fungus, like a cultivated mushroom that had been sweating in the fridge for too long.

I cycled past again on 10th April 2022 and was shocked and saddened to see that the Oak tree had gone. The gales in late February may have toppled it, or a farmer or tree surgeon may have seen the brackets and decided to remove the tree. There were only some thin twigs left, plus a few shattered remains of very woody (and not at all smelly) Oak Bracket on the ground. I took one home as a souvenir.

Broad-leaved Ragwort, Senecio sarracenicus

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Broad-leaved Ragwort, Senecio sarracenicus

Broad-leaved Ragwort, Senecio sarracenicus at Wheatfen. Growing along the edges of the wood, where it looked as if it was part of a wild herbaceous border.

I’m lucky to live close to some very special places, one of which is Wheatfen Nature Reserve, on the south bank of the River Yare just east of Norwich. I visited a couple of weeks ago to look at plants and late summer insects, and walked through Home Marsh, a part of the reserve I haven’t visited before at this time of year.

I found a new species (for me), which I had to look up in my books when I came home: Broad-leaved Ragwort, Senecio sarracenicus. It is a statuesque plant, clearly a type of Ragwort, with the typical yellow daisy flowers, but with broad leaves, green on both the upper and lower sides. It was growing in large clumps in the marsh and along the edges of the wood, where it looked as if it was part of a wild herbaceous border.

Broad-leaved Ragwort, Senecio sarracenicus, is a hardy perennial that grows to 1.5 or even two metres tall in damp places and is in flower from July to September (and possibly earlier in some places: the Wildflower Finder website says it flowers from May to July). It is a member of the Asteraceae (formerly Compositae, the Daisy family) and a close relative of the superb wildlife plant our native Common Ragwort (Jacobaea vulgaris).

In the British Isles, Senecio sarracenicus is a neophyte and was introduced in 1632 (note 1). It is a native of other parts of Europe, to Siberia and Turkey. The NBN Atlas website has a map of British records, though this misses out the known sites in Norfolk: Wheatfen, Hoveton and Martham (note 2). Most records are from Scotland and the north of England.

The Wild Flower Finder, UK Wildflowers and Nature Gate websites have some good photographs of Broad-leaved Ragwort, which was formerly known as Senecio fluviatilis. Its older English names include Saracen’s Woundwort, Saracen’s Comfrey and Saracen’s Consound.

So why is Broad-leaved Ragwort growing at Wheatfen?

I found the answer in a booklet I’d bought on a previous trip to the reserve (note 3).

For forty years Wheatfen was the home of by Ted Ellis (1909-1986), the naturalist, writer and broadcaster (note 4).

In the 1930s Ted tried to reintroduce the Large Copper butterfly to Wheatfen. The butterfly used to occur in fens in East Anglia and Lincolnshire and was “once widespread” at Wheatfen. He planted Broad-leaved Ragwort to provide late summer nectar for the Large Coppers.

The Large Copper’s foodplant is Water Dock (Rumex hydrolapathum), which is abundant on the reserve but the project failed, as did the more well known reintroduction at Woodwalton Fen (note 5).

The plant lives on and is thriving, long after the Large Coppers – and Ted Ellis – have gone.

Broad-leaved Ragwort ,Senecio sarracenicus

Broad-leaved Ragwort, Senecio sarracenicus

Notes

Note 1 – From p72,  ‘Alien Plants’ by Clive A. Stace and Michael J. Crawley (Harper Collins, 2015). Neophytes are plants introduced to the British Isles after 1492.

Note 2 – Gillian Beckett, Alec Bull and Robin Stevenson, ‘A Flora of Norfolk’. Privately published. (1999).

Note 3 – The Ted Ellis Trust. ‘Wildflowers of a Broadland Reserve Wheatfen. Part 1: Species of the fen and reedbeds.’ (Written by Will Fitch, the current warden.)

Note 4 – My first encounter with Ted Ellis was as a child, when I had several of his wildlife guides, packed full of photographs, published in Norwich by Jarrold Colour Publications and written by “E.A. Ellis”. At the time I didn’t imagine I would one day live in Norwich.

After his death, the Ted Ellis Trust was set up to look after Wheatfen.

Note 5 – The Large Copper reintroduction project at Woodwalton Fen ran from 1927 until the early 1990s. Our own sub-species, Lycaena dispar ssp. dispar became extinct in 1851 (or perhaps as late as 1864), so the Dutch subspecies, Lycaena dispar ssp. batavus, was used.

I visited Woodwalton Fen on a Botany field trip in 1983 and while I was there I saw several Large Coppers flying in the warden’s greenhouse, but sadly not in the wild.

‘The Butterflies of Britain & Ireland’ by Jeremy Thomas and Richard Lewington (British Wildlife Publishing, 2014) gives more useful information.

Alder Tongue, Taphrina alni

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Alder Tongue, Taphrina alni

Alder Tongue, Taphrina alni. Upton Fen, August 2020.

At this time of year we go looking for Alder Tongue fungi, Taphrina alni. We usually find some on the Alder trees by the River Wensum at Sweetbriar Marshes in Norwich, not far from where we find Alder Goblets in the late winter.

So last Sunday afternoon we went to have a look. We saw several, on the lower branches of Common Alder trees beside the tarred path that runs between the Mile Cross and Sweetbriar Road bridges.

Alder Tongues are a type of plant gall. The Ascomycete fungus Taphrina alni infects an Alder tree and produces chemicals that alter the growth of the woody female catkins (pseudocones), producing the distinctive tongue-like growth, which can grow to at least twice the length of the catkin. The structure is sometimes known as a “languet” (something that resembles a tongue).

The “tongue” tissue derives mainly from the ovarian tissues of the alder catkin or from its bracteoles. (Apparently those curling down usually come from the bracteoles tissues and those projecting upwards usually come from ovarian tissues.) Alder Tongues are smooth-edged and grooved and usually curved.

The fungus produces sexual spores from its asci, which are embedded in the gall tissue, and these are carried by the wind to infect other trees. Often a single female catkin has several Alder Tongues growing from it but sometimes the gall doesn’t develop properly – the Plant Parasites of Europe website has photographs of a gall that has failed to grow.

Alder Tongues can be green, cream, red, purple or brown. Specimens produced early in the season (July or early August) tend to be green, whereas later specimens (mid August onwards) are usually more richly coloured. Old Alder Tongues are brown and the dried structure persists into winter on the mature, browny black pseudocones. They may still be attached to fallen pseudocones in late winter.

Alder Tongue, Taphrina alni

Young, fresh Alder Tongue, Taphrina alni. Sweetbriar Marshes, Norwich, last week.

Alder Tongue, Taphrina alni

Older, brown, Alder Tongues, Taphrina alni. Sweetbriar Marshes, Norwich, last week.

Taphrina alni has been recorded from many parts of the British Isles, though mainly north of a line from the Thames and Severn estuaries. It has been found as far north as Orkney. (The NBN Atlas had 654 records at the time of writing.) It appears to be becoming more common, with an increase in sightings since the 1990s.

Outside the British Isles, Taphrina alni occurs in several European countries, including Germany, Switzerland, Norway and Denmark. It is has also been found in the USA and Canada.

Other species of Taphrina also cause gall formation in their hosts.

Taphrina betulina causes a gall known as a Witches’ Broom, a dense twig-like formation in the branches of a birch tree. It is the size and shape of a squirrel’s drey and is most obvious in winter, once birch trees have lost their leaves. (But beware: similar growths can also be caused by several other organisms, including other fungi, insects, mites, nematodes and viruses.)

Pocket Plums are caused by Taphrina pruni. The fungus infects Blackthorn (Prunus spinosa) and other species of Prunus, included domesticate varieties of Plum. Infected fruit develop into elongated green structures that resemble small runner beans. affected fruit have no stone.

There are some good photographs of Alder Tongues on the NatureSpot, Living Levels and Botany In Scotland websites.