During dry spells sandy, stony substrates can cause drought stress in plants unless their roots are deep in the soil or they possess other adaptations to dry conditions. Amazingly, there are fungi which thrive in dry, infertile habitats even though they lack roots. Here are a few that are easily overlooked but popped up in my yard in Sept-Oct of this year during what turns out to have been developing drought conditions. Pisolithus tinctorius is a variably colored upright species sometimes with a lobed or stalked appearance that appears in dry coarse soils. Its bizarre appearance has suggested the common name of ‘Dead Man’s Foot’. This specimen is nearly 15 cm high. All photographs are of fungi that appeared naturally in my yard.
Note how the Pisolithus spore mass disintegrates when the fungus is disturbed (below).
In Pisolithus, the spores are initially contained within small, granular-like capsules (peridioles) that develop within the spore case. With maturation, the walls of the peridioles break down releasing the powdery spores.
Fungi belonging to the genus Scleroderma are thick-skinned and form low stocky fruiting bodies that may be hard to discern when growing in stony soil. They resemble puffballs in shape but are much thicker and resistant to adverse conditions. Some species of Scleroderma release spores from an apical slit while in others the fruiting body splits open forming lobes that peel back exposing the spores. Initially the spores form a dense mass that separates after desiccation.
In this follow-up photograph (above), the same fungus is seen two days later with the spore mass ejected.
In another species, spore-release is achieved by a natural peeling-back of the spore case.
Daldinia is a genus of tough saprotrophic species that colonize dead wood and persist (dead or alive) for long periods (likely months or more). The species shown here forms hard fruiting bodies about 0.5 cm in diameter covered in small pimple-like protrusions. It is unclear as to whether the fungi or the lichens first colonized the branch which fell to the ground already well colonized. Some Daldinia species are called ‘cramp balls’ and resemble pieces of charcoal. A related genus (Ditrype) forms a black crustose layer on larger (dead) branches that resembles dried tar or paint! Daldinia is classified as belonging to the Ascomycetes and is only distantly related to the Scleroderma and Pisolithus species discussed above. The latter two belong to the Basidiomycetes, the second major sub-divison of the Fungi.