Clavulinopsis fusiformis

Clavulinopsis fusiformis is a clavarioid fungus in the family Clavariaceae. In the UK, it has been given the recommended English name of golden spindles. In North America it has also been called spindle-shaped yellow coral or golden fairy spindle. Clavulinopsis fusiformis forms cylindrical, bright yellow fruit bodies that grow in dense clusters on the ground in agriculturally unimproved grassland or in woodland litter. It was originally described from England and is part of a species complex as yet unresolved.

Taxonomy and etymology
The species was first described in 1799 by English botanist and mycologist James Sowerby from collections made in Hampstead Heath in London. It was transferred to Clavulinopsis by English mycologist E.J.H. Corner in 1950. Initial molecular research, based on cladistic analysis of DNA sequences, indicates that C. fusiformis is part of a complex of related species.

The specific epithet fusiformis, derived from Latin, means "spindle-shaped".

Description
The fruit bodies of Clavulinopsis fusiformis are cylindrical, bright yellow, up to 150 x 10 mm, growing in fasciculate (densely crowded) clusters. Microscopically, the hyphae are hyaline, up to 12 μm diameter, with clamp connections. The basidiospores are hyaline, smooth, globose to subglobose, 4.5 to 7.5 μm, with a large apiculus.

Similar species
In European grasslands, Clavulinopsis helvola, C. laeticolor, and C. luteoalba have similarly coloured, simple fruit bodies but are typically smaller and grow singly or sparsely clustered. The uncommon Clavaria amoenoides produces densely clustered fruit bodies but they are pale yellow and, microscopically, lack clamp connections.

Distribution and habitat
The species was initially described from England and is common throughout Europe. Its distribution outside Europe is uncertain because of confusion with similar, closely related species in the complex. Clavulinopsis fusiformis sensu lato has been reported from North America, Central and South America, and Asia, including Iran, China, Nepal, and Japan.

The species typically occurs in large, dense clusters on the ground and is presumed to be saprotrophic. In Europe it generally occurs in agriculturally unimproved, short-sward grassland (pastures and lawns). Such waxcap grasslands are a declining and threatened habitat, but Clavulinopsis fusiformis is one of the commoner species and is not currently considered of conservation concern. Elsewhere, C. fusiformis sensu lato occurs in woodland. In China it is one of the dominant macrofungal species found in Fargesia spathacea-dominated community forest at an elevation of 2600 –.

Economic usage
Fruit bodies are commonly collected and consumed in Nepal, where the fungus is known locally as Kesari chyau.

Chemistry
Extracts of "Clavulinopsis fusiformis" from Japan have been found to contain anti-B red blood cell agglutinin.