Melanoleuca cognata (Spring Cavalier)
English Name: Spring Cavalier
(other scientific names include Agaricus arcuatus var. cognata, Tricholoma cognatum and Tricholoma arcuatum var. robusta)
At last an umbrella shaped fungus of the month with a stipe, cap and gills! This is a white-spored species that fruits twice, once in April and May and then again from August onwards through the usual fruiting period until the frosts stop play. Given that it often appears when very little else is fruiting, it is the most common large toadstool that comes my way during the spring.
The genus Melanoleuca doesn’t have any veil structures and the crowded gills are mostly emarginate (i.e. dinking up toward the cap and then back down again as they attach to the stipe). The stipe is usually pale and slender relative to the width of the cap. The early fruiting and the beautiful pinkish cream colour (sometimes salmon or almost apricot) of the gills really helps to identify this particular species.
As with other species in the genus, M. cognata is not a small fungus; the cap occasionally expands to 14cm although more usually around 8cm. The cap usually has the low, central umbo and broad sweeping edges that give the genus its English name. It is variable in both colour and texture and can be either dry or greasy and coloured from buff through to darker browns. Some mycologists separate out a variety with a dark coloured cap and astringent taste as M. cognata var. nauseosum but the recent book of keys ‘Funga Nordica’ lumps them together.
This is a lovely genus to look at under the microscope with a range of cystidia shapes, including some with crystals adhering to the top. The white spores are actually very finely warted - amyloid (stain blue/black) in Melzer’s Reagent.
Find out more about the macro characters described above and using the microscope.
Fruiting:
This species has two fruiting slots – a first in April and May and then a second from August onwards until the hard frosts.
Habitat:
The genus is considered to be saprotrophic, feeding off organic litter or wood chips. It is thus often found in gardens, particularly around compost heaps as well as along woodland edges and tracksides.
Distribution:
The checklist gives this species as occasional in England and rarely recorded elsewhere. There are 47 Scottish records on the FRDBI dating back to 1959 distributed from East Sutherland to Dumfries and Galloway. The total number of UK records on the database is 448, so there is some way to go in Scotland before we really understand the frequency with which this species fruits.
Liz Holden May 2012
Melanoleuca cognata (Spring Cavalier) the gills are not looking quite as creamy pink in the photo as they often do in reality. See the photos below for some perhaps more typical fruitbodies.
Many thanks to Robert MacPherson for the above three images of Melanoleuca cognata.