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18 Nov 2021

The strange case of the Strathy Strangler

Written by Roddy Hamilton, Ranger in our North East region
A pink cone-shaped mushroom grows on a lawn, with a grand stately home in the background.
Mushroom on the lawn at Haddo House (Hygrocybe calyptriformis) | © Photo by Mary Bain
It’s autumn and we are waiting, just like elsewhere, for small coloured mushrooms to sprout from between the grass blades. At this time you will find at least one warmly wrapped person staring at the grass. Bent over, they will examine these colourful gems of the lawn, most likely scratch their chin, and then take a photograph of whatever they have found.

Autumn brings fungi, the natural recyclers of our environment. There is much colour and variety to this kingdom’s contribution but none more so than the waxcap mushrooms which can be seen on our properties. This year has been a bumper one for fungi and the woodlands are currently a riot of colour, but fungi’s autumn trump card is yet to be played – and it’s played on lawns.

Like other properties at the National Trust for Scotland, there are lawns which historical maps show have been there for a very long time. This longevity creates perfect conditions for a range of fungal species which are recognised as internationally important. And it’s on these lawns that the inscrutable colourists of the mushroom world live out their lives. A number of Trust properties have lawns with waxcaps, but the most diverse and greatest display can be found on the lawns of Haddo House.

An aerial view of Haddo House, showing its Georgian symmetrical design. It is surrounded by tall trees, large lawns and a country park.
An aerial view of Haddo House

Waxcaps are small, colourful mushrooms which, as the name suggests, have a waxy feel. They are choosy about their grasslands and prefer those which have been grazed (or mown) and to which there have been no added fertilisers. Their contribution to the grassland ecosystem is still poorly understood. The mushroom which is visible above ground is only part of the organism – the fruiting body, the part which emerges above the soil surface to release spores from its gills. Most of it lives as a network of thin threads called hyphae, which connect living plant material from underground.

It’s still not clear exactly how the waxcaps operate. They probably form associations with grasses or mosses, receiving sugars from these plants in return for delivering minerals, which the waxcaps collect using their hyphae. Some species will consume dying plant material.

The lawns at Haddo are managed for the waxcaps. Waxcaps need the grass to be short but not too short. A difference of only a centimetre or two in the sward height (the expanse of grass) changes the microclimate down at ground level considerably.

This year’s weather – one of the driest summers on record – may not have helped the waxcaps, or have caused them to be fruiting later. Although there are reports of waxcaps elsewhere, we have to wait for the annual Haddo display. Waxcaps are known for sometimes being as late to the party as mid-December! So in October, as the clocks wind back and that valuable hour is stolen from our teatimes, it is sublime when waxcaps do appear, seemingly overnight, to festoon the misty morning lawns with reds, yellows, greens and oranges.

A range of mushrooms with long stalks lie across the palm of someone's hand. The smallest is a very dark green and on the left. The largest is in the middle, with a yellowy cap and pale green stalk. On the right is a mushroom with a bright yellow cap and orange stalk.
An assortment of waxcaps found at Haddo House | © Photo by Liz Holden

In 1995, Rald invented a scale for fungal biodiversity in grasslands called the CHEG score. This reflection of fungal biodiversity in a grassland area has been adopted as a standard. Importance is placed on this score because a high CHEG score could mean a conservation designation for a site.

CHEG is an anacronym for Clavaria, Hygrocybe, Enteloma and Geoglossum. These are the different genera, which are grouped together and scored. Clavaria are coral-like fungi. Waxcaps belong to the genus Hygrocybe. Enteloma are subtle mushrooms known as pink-gills. Geoglossum are usually black and club-like in shape, and their name literally translates to ‘earth tongues’ (by which they are also known).

We wait for the waxcaps at Haddo because when they arrive they are, on close inspection, a diverse range of characters, and often quite cryptic – if you’re of a mind, it’s important to know which kind they are.

Which takes us back to the warmly wrapped person. Hands up – that’s me.

An orange waxcap fungus bent over, showing its gills, with a smaller waxcap beside it, in grassland.
The splendid waxcap, one of the many varieties of red-coloured waxcaps easily confused at first glance | © Photo by Laurie Campbell

While they are beautiful to behold, waxcaps are sometimes less than eager to give up their exact identity. It’s human nature to group them by colour. That should make it easier, you think, until you find that sometimes they change colour. The blackening waxcap is a beautiful deep orange-red. However, after time (sometimes around Halloween) it turns black. It is sometimes known as the witch’s hat and it’s easy to see why.

Then let’s take the other reds: the crimson waxcap, the scarlet waxcap, the splendid waxcap – all red, all quite variable. And this is where the figure on the lawn behaves even more strangely, because the first step in the identification key is to decide if the stalk or cap is slippery. Or if the cap is sticky. (The best way to check this is to rest it on your lip. If it sticks, it’s sticky.)

But then again, some are greasy only when it’s humid and are dry when the air is dry. Lucky, then, that you can rely on smell. If Hygrocybe quieta, the oily waxcap, does not reveal itself by its oily touch, then perhaps its oily smell might give it away. Smells are quite important in the identification (and can be strangely more-ish). The honey waxcap has a wonderful fragrance, and there’s one identification key which suggests you look for smells of cedarwood or of Russian leather.

Some are, of course, unmistakeable by their appearance. The parrot waxcap (Hygrocybe psittacina) has a vibrant suffusion of green and yellow in its colouring. No guesses where its name comes from. And, character of characters, Porpolomopsis calyptriformis, the ballerina waxcap. As if stills from an animation, you can see columns of it sometimes caught mid-pirouette, tilting this way and that – the cap a ballerina’s tutu whirling.

Haddo has 18 species of waxcap. But it’s not just waxcaps nor the 17 species of pink-gill which makes its biodiversity impressive.

It also has 9 species of Clavaria or coral. These are peculiar-looking fungi, whose appearance, like minced play-clay, is miles from the waxcaps. Look at the pathsides in the terrace garden at Haddo in November and you will see them. Smoky spindles and violet coral abound. These fungi have no gills and so ‘shoot’ their spores from their worm-like surfaces. What do these fungi find so irresistible here? No-one knows exactly. And it is this, the cryptic nature of fungi, that so appeals.

An unusual looking fungus grows in grass. It resembles a pile of pink worms, squirming in a ball.
Smoky spindles (Clavaria fumosa) | © Photo by Liz Holden

In the ecology of lawns and fungi, perhaps the most bizarre of all is the case of a mushroom called the Strathy strangler. Previously found at Haddo, it provides unexpected drama. The Strathy strangler is one which parasitises another mushroom, called the earthy powdercap.

The earthy powdercap is regularly seen on the lawn at Haddo. It is orangey-brown, has a granular surface to the cap and a ring on its stem. Though it is rarely seen in this country, the earthy powdercap’s nemesis, the Strathy strangler, is sometimes also seen at Haddo. The strangler wends its hyphal threads underground to where the earthy powdercap is. It grows up the inside of the earthy powdercap’s stem, which it leaves intact. Then it consumes its cap, replacing it – in a final act of audacity – with its own.

And you thought the lawns were a quiet place.

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