'Extremely rare' smut-fungus found on Naked Lady crocus

Sooty-black smut fungus, Urocystis colchici
Image caption The smut is totally dependant on the crocus and has been described as being in a classification "one below extinction".

An extremely rare fungus has been found on a single plant in Gloucestershire.

The sooty-black smut fungus, Urocystis colchici, was spotted at Westonbirt Arboretum by the Wiltshire and Swindon Biological Records Centre (WSBRC).

The fungus which is classified as "critically endangered" infects the leaves of the UK's only native crocus Colchicum autumnale or Naked Lady.

WSRBC's Dave Shorten, said: "I would have done a little dance when I found it but I didn't want to stand on it."

Image caption The plant gets its name from flowering in the autumn, naked and without its spring leaves

The fungus was discovered on two leaves of a single plant, following an intensive search of hundreds of crocus plants in Westonbirt's Silkwood.

Listed as a critically endangered species by the British Mycological Society, Mr Shorten said it was not only "extremely rare" but a legally protected species and "should not be picked".

"Very little is known about it - this is only the third time it has been sighted since 1938," he said.

"And there have only been 27 recorded sightings of it ever in well over a century and a half and a high proportion of those records are duplicates."

'Near extinction'

The smut-fungus is so called because its spores appear as a sooty black colour whilst Naked Ladies get their name from flowering in the autumn, naked without their spring leaves.

Dr Martyn Ainsworth, mycologist at Kew Gardens, said the host plant was itself classified as "near threatened" and the smut-fungus "totally dependent" on it.

"The smut is on the current list as critically endangered which is just one below extinct - it's the last saloon before extinction," he said.

"So this find - the third in England since the second World War - made my day."

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