(iv) Resupinate fungi
When mycologists talk generally about ‘resupinates’ they are referring to a whole group of Basidiomycetes whose spore-bearing layer is exposed, the cap highly reduced or completely lacking, and the fungus adhering to the surface of the substrate which may be soil, wood, grasses, etc., at the point which would have been the cap of an agaric. Probably members of the group are the most commonly seen yet it is one of the most commonly ignored groups of fungi—by naturalists and mycologists alike; they form ‘white wash’ on old sticks, dark coloured discolourations on trunks, etc. It is an entirely artificial group of many quite unrelated elements united on the common factor of having either a reduced or primitive fruit-body consisting only of a sheet of tissue. However, these same fungi have a uniting factor in that they frequent the same ecological sites, e.g. on muddy soil in bogs, under overhangs of banks and stream sides, undersides of logs, trunks, branches and twigs, hidden in cracks of old stumps or spreading over carpets of conifer needles or dead leaves and sedges.
By studying the anatomy of the fruit-body and the characters of the spores certain relationships can be found which relate many of these fungi to several other groups of fungi we have dealt with in earlier chapters.
It is only possible to mention here the group as a whole for all the species really require very careful examination, often necessitating several hours of microscope work. They should be left by the beginner until more experience is obtained and advice of an expert easily available.
Although the group mainly contains saprophytes, a few are parasitic. ‘Silver-leaf disease’ of almonds and fruit trees is caused by Stereum (chondrostereum) purpureum (Persoon) Fries; it has a purple fruiting surface, and greyish upper surface when ever this is formed at the margin.
There are several species of Stereum in Britain, three species of which when handled in the fresh state stain red: S. sanguinolentum (A. & S.) Fries, a pale coloured species on conifer wood, S. rugosum (Pers.) Fries a similar coloured species on beech, birch and especially hazel, and S. gausapatum Fries an ochraceous yellow species on oak, often forming a pocket rot of the timber. However, the commonest member of the genus is an orange-tawny coloured species with a greyish buff, hairy cap, S. hirsutum (Willd) Fries. It grows on many trees of broad-leaved wood and can be found wherever twigs, branches, trunks or stumps have been lying out in the rain; it does not bleed.
Plate 59. Resupinate fungi
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Those species of resupinate fungi which resemble members of this genus, i.e. those with a distinct tough, although poorly developed, cap, are called stereoid.
‘Red thread disease’ of grass which often causes unsightly red patches on lawns and school and corporation playing-fields is caused by Corticium fuciforme (Berkeley) Wakefield. Fungi belonging to this genus produce fruit-bodies which ‘scramble’ over the substrate; for example, if one searches old elder trees throughout the year one will certainly find a ‘white wash’ fungus of this type, Hyphodontia sambuci (Pers.) J. Eriksson. Fungi with this type of fruit-body are called corticoid.
The two major types are illustrated along with some of the bizarre microscopic structures one finds in the resupinates; such structures are useful in classification and identification, and their beauty and intricacy make up for the surprisingly simple fruit-body shape and texture.