Jeremy Bartlett's LET IT GROW blog

The wonder of plants and fungi.

Porcelain Fungus, Oudemansiella mucida

Posted on 20 October, 2016 by Jeremy Bartlett1 November, 2018

Porcelain Fungus, Oudemansiella mucida. Photograph by Vanna Bartlett.

Autumn seemed to arrive suddenly this year. In the last week of September it was still summer, then temperatures became more seasonal and we had some rain at last. With autumn came fungi.

On Monday we walked through the woods at Felbrigg Hall in North Norfolk. This is where I saw my first Porcelain Fungus (Oudemansiella mucida) several years ago. It was high up in a Beech tree but nonetheless the shiny white fruit bodies were unmistakable (see some great photos here). This time, however, we were lucky enough to find the fungus on a Beech stump and we could admire it in all its shining, slimy glory.

Porcelain Fungus can be found throughout northern and central Europe (see UK distribution) and grows on dead or dying Beech trees, or on dying Beech branches. Autumn is the time of year to see it. Sometimes it is very plentiful and the fruit bodies can cover an entire tree.

Porcelain Fungus is very slimy and its specific name, mucida, refers to the layer of transparent mucus that covers the fungus’ cap. The genus Oudemansiella contains between 15 and 42 species, depending on which classification system is used, and is named after the Dutch mycologist Cornelius Anton Jan Abraham Oudemans (1825–1906). Other English names for Porcelain Fungus include Poached Egg Fungus and Slimy Beech Cap.

The fungus is edible, though I haven’t tried it yet. It has the advantage of not looking like anything else, but if you do decide to try it, remove the mucus first. John Wright (in the River Cottage Mushrooms Handbook, which I have recommended before) describes how he was converted to eating this fungus. The mucus should be washed off and tough stems removed and then the caps can be sauteed. Apparently the flavour is “surprisingly rich”. The Wild Food UK website says Porcelain Fungus has a “good mushroomy taste”.

Porcelain Fungus fights off competing fungi by producing fungicides called strobilurins. (The name comes from Strobilurus tenacellus, the Pinecone Cap, which is where the compounds were first isolated. The Pinecone Cap uses strobilurins to stop competing fungi from growing on the pine cones on which it grows.)

According to an article in Pest Management Science entitled ‘The strobilurin fungicides‘ (D. Bartlett et. al 2002), commercially produced strobilurins were first sold in 1996 and sales totalled approximately $620 million in 1999, representing over 10% of the global fungicide market.

In the UK, DEFRA produces a fact sheet on strobilurins, ‘Use of Strobilurin Fungicides on Cereals‘ and The American Phytopathological Society has produced ‘Q_oI (Strobilurin) Fungicides: Benefits and Risks‘ on its website, which explains how the fungicides are applied. Strobilurins work by blocking electron transport in mitochondria so that they can no longer produce energy. Since their introduction in agriculture, some fungi have become resistant to strobilurins, so they are now used more sparingly, often in conjunction with other chemicals. (See also ‘Resistance Management is Essential with Strobilurin Fungicides‘.)

Hemp Agrimony, Eupatorium cannabinum

Posted on 17 September, 2016 by Jeremy Bartlett17 September, 2016

Peacock butterfly feeding on Hemp Agrimony

As summer reaches its end Hemp Agrimony, Eupatorium cannabinum, is coming towards the end of its flowering period. It is one of the glories of the summer, with frothy, pinkish flower clusters that appear from July to September and are often covered in insects, especially butterflies and hoverflies.

Hemp Agrimony (sometimes given a hyphen: Hemp-agrimony) is a native of the British Isles and other parts of Europe. It is a perennial herb and is found on base-enriched soils in a wide range of damp or wet habitats. Hemp Agrimony grows along the edges of ponds, lakes, canals and rivers and in fens, damp meadows and wet woodland. In some places it can also be found in dry woods, on hedge banks or on waste ground. It is more coastal further north but its range extends to Ireland and parts of Northern Scotland (see map).

A member of the Daisy family, Asteraceae, Hemp Agrimony is a bushy plant with flat-topped heads of numerous tiny pink flowers. (There are some great photographs of the plant on the Wildflower Finder website.) The flowers are followed by fluffy white seeds in autumn, which are spread by the wind. Hemp Agrimony’s trifoliate leaves, which have long, toothed leaflets, are attached in pairs to a reddish stem, which can grow between one and two metres tall. The name ‘Hemp Agrimony’ comes from the leaves’ resemblance to those of Hemp (Cannabis sativa). This resemblance is only superficial and Hemp Agrimony does not contain the cannabinoids that are found in Hemp (a member of a separate family, the Cannabaceae, which also contains Hops). Nonetheless, Flora Britannica relates the story of a raid on the Sussex Trust for Nature Headquarters by the Drugs Squad, because someone mistakenly thought the plant was Cannabis.

Hemp Agrimony has sometimes been used medicinally and the Modern Herbal and The Herbal Resource websites list uses including purifying the blood and treating jaundice, fevers and influenza. However, the plant contains pyrrolizidine alkaloids and these can cause liver damage, so beware! (Also see my post about Coltsfoot, Tussilago farfara, from March 2012.)

Eupatorium cannabinum has several other English names as well as Hemp Agrimony and Hemp-agrimony, including Raspberries and Cream (from the appearance of the flowers), Ague Weed (from its use in treating fevers), Holy Rope, St. John’s Herb, Sweet Mandulin, Sweet-Smelling Trefoil, Thoroughwort, Waterhemp and Water Maudlin.

If you have a damp and sunny or partly shaded area in your garden, Hemp Agrimony is worth growing. The related Eupatorium purpureum, from North America, known as Joe Pye Weed, has darker flowers and is also a good choice for gardens. It looks especially good with other late-flowering perennials, such as Rudbeckia and Helenium.

Purple Hairstreak butterfly on Hemp Agrimony

Purple Hairstreak butterflies usually stay up at tree top level, but this one has been tempted down by Hemp Agrimony.

Buddleja (a.k.a. Buddleia) – the butterfly bush

Posted on 19 August, 2016 by Jeremy Bartlett1 November, 2018

It’s nearly a month since I wrote my last blog post, because the weather has been sunny and warm and I’ve spent quite a bit of time out and about looking for butterflies and other insects. I have photographed many of these on Buddleja bushes in various parts of Norfolk. It is not surprising that the most commonly grown species, Buddleja davidii, is known as the Butterfly Bush.

Red Admiral butterfly on Buddleija davidii

I tend to spell Buddleja with an “i” – “Buddleia” – and this was the spelling I grew up with. However, Linnaeus used the spelling Buddleja and this has now been adopted as the correct spelling. The genus Buddleja is in its own family, the Buddlejaceae, and the name was given to commemorate the Reverend Adam Buddle (1662–1715), an English cleric and botanist who spent much of his life in East Anglia.

Buddleja davidii comes from China and is one of a number of shrubs in the genus. It grows easily in gardens, preferring a sunny spot, though even in shade its tall branches can grow up into the sun within a season. Flower spikes are produced in July, August and September at the top of the same season’s growth. The flowers are strongly scented and can be a bit overpowering on a hot sunny day. Outdoors they are pleasant but in a vase indoors their presence rapidly overpowers and I’ve only tried them as cut flowers once, for about an hour.

Left to its own devices, a Buddleja davidii bush can grow very large. New shoots grow outwards and upwards each year and soon the flowers are about fifteen to twenty feet (4 – 6 metres) tall and too tall to see any insects (especially butterflies) that are attracted to them. It is a good idea to prune the bushes every year, to about a foot (30cm) from the ground. This can be done in autumn or early spring – I cut mine in March. Cut stems can be used as hardwood cuttings in winter, if you want to propagate. They are very easy to grow: I use my Buddleja sticks to mark rows of seedlings on my allotment and a few of these markers sprout leaves every year! Cuttings are a good way to produce plants with the same flower colour as the parent, if you have a cultivar you particularly like. Buddleija davidii produces copious seed in the south of Britain, but the resulting plants will usually have pale mauve flowers.

Since Buddleija davidii self-seeds so readily, it can become a very invasive plant in urban areas and on waste ground or on railway tracks. The species was introduced to Kew Gardens in 1896 and was growing in the wild in the UK by the 1920s. In 2008 DEFRA estimated that Buddleja costs the British economy £961,000 per year, because it damages old buildings and has to be cleared from railway tracks. Maybe this isn’t entirely bad: a Buddleja seeded into our chimney on our previous house and cost us money (bad for us) but it also provided employment to a local handyman (good for him and the local economy). Butterfly Conservation have produced a very sensible Position Statement about Buddleja davidii, which suggests ways to use the plant to encourage butterflies without it becoming a nuisance. The RSPB also give advice, including alternative plants for attracting butterflies. I find that Verbena bonariensis is especially attractive to butterflies, even when a Buddleja davidii is in flower right beside it.

Buddleja davidii is also an invasive species in some other parts of the world and is banned in some parts of the United States. On her Toronto Gardening All Year Round blog, Rosemary Waigh recommends some alternative plants for attracting butterflies in the United States and Canada.

Buddleja seeds are appreciated by birds but if you’re concerned about the plant spreading, you can remove the spent flowerheads when they turn brown, which also makes the plant flower longer. (Seeds don’t develop until late winter.) If you prune some bushes in autumn and some later in spring you will also prolong the flowering season.

There are other, more refined, varieties of Buddleja. Buddleja x weyeriana is the name given to hybrids between Buddleja davidii and the spring flowering “Orange Ball Tree”, Buddleja globosa. Flowers of B. x weyeriana are intermediate between the two parents, but the flowers are produced slightly later than Buddleja davidii. Flower colour varies, so it’s a good idea to look for one in nursery or garden centre in August, so you can see the flowers before buying. Variety ‘Sungold’ is one of the loveliest, with clear yellow flowers. We grow a form with a mix of mauve and yellow in the flowers, perhaps a variant of ‘Moonlight’. Ours attracts butterflies and bees just like B. davidii. Growth and pruning are like B. davidii. Not everyone is a fan – the late Christopher Lloyd wrote that B. x weyeriana “combines the worst features of both parents in a sickly orange, pink and mauve vomit.” I think that was very unkind, but you can decide.

Buddleja globosa flowers in early summer and for this reason I have rarely seen butterflies on the blooms, though the flowers have plenty of nectar and are loved by bees. The shrub needs very little pruning.

Bumblebees on Buddleja globosa

We also grow Buddleja alternifolia. This is an elegant plant, though it can grow as big as any other Buddleja (3 metres high and 4 metres across). It has smaller, alternate leaves which look a bit like willow, and elegant arches of pale mauve flowers. The flowers are produced on the previous year’s shoots in late spring, so pruning is very different from Buddleja davidii. As with B. globosa, bees like the flowers. The species is not invasive in the UK.

A fine specimen of Buddleja alternifolia, in the Bishop’s Garden in Norwich.

There is a lot of other interesting information on different species and varieties of Buddleja on the web. I can recommend the The Telegraph’s article “The Butterfly Effect: blossoming buddleia” and the Urban Butterfly Garden and The Buddleia Garden websites. The Plants for a Future website reports no known uses of Buddleja for human food or medicine, but the flowers can be used to make dyes.