More Fungi

Introduction to fungus biology

Lycoperdon (Puffball)


This is probably Lycoperdon pyriforme (Stump Puffball). It is the only puffball in the British Isles to invariably grow on rotting wood (sometimes submerged) and tree-stumps. When young it is covered with minute spines, granules or warts which soon fall away to leave a smooth whiter surface. The texture and overall appearance also made me think of Scleroderma areolatum (Leopard Earthball) but the latter has a tough, hard and leathery wall whereas Lycoperdon has a thin papery wall, as in this case. Earthballs also usually lack stems, whereas these were clearly pear or pestle-shaped. Puffballs, with their more papery skins, also have a more efficient bellows mechanism, with the slightest touch deforming the skin to discharge a cloud of spores.

This fungus is a gasteromycete ('stomach fungus' due to its sac-like body) a mixed group which includes puffballs (e.g. Lycoperdon), earth-balls (e.g. Scleroderma), giant puffballs, earth-stars, bird's-nest fungi and stink-horns. The gasteromycetes are a collection of various basidiomycetes with a similar morphology and is a polyphyletic group (a group containing several distinct taxa with different evolutionary origins). The modern taxonomic preference is for classification that reflects evolutionary processes rather than morphological similarities. From a field perspective, however, we need a scheme that makes it easier to describe and determine the species of a specimen and 'gasteromycete' remains a useful descriptive term. One can hope that both classification schemes are not too dissimilar.

The puffballs include Lycoperdon, Calvatia and Geastrum (earthstars) Calvatia gigantea is the giant puffball. I do not wish to got bogged-down on issues of taxonomy here.


The ripe sporing body of a Lycoperdon puffball consists of a thin papery skin or peridium, in some species covered with scales or spines, and an internal darker spore-producing mass called the gleba. When ripe the structure opens via a regular pore in Lycoperdon (An irregular fissure in Scleroderma). The lightest touch or a falling rain drop will deform the peridium slightly causing a puff of spores to be released. This exploits the kinetic energy of animals and the force of gravity as gravitational potential energy is converted into the kinetic energy of a falling object, such as a raindrop. Earthballs rely more on animals and wind to disperse their spores.

The gleba is divided into a number of spongelike cavities which are lined by the hymenium when fertile. The partitions are made up of thin and thick-walled hyphae, the thin-walled hyphae break down as the sporing body ripens, presumably supplying nutrients and/or materials for wall formation in the ripening spores. The thick-walled hyphae persist as capillitium threads among the spores. Beneath the gleba there is usually a non-sporing region called the sub-gleba, which extends into the gleba sporing-mass as a small column (columella). The wall or peridium consists of two layers, the inner hyphal layer or endoperidium and the outer pseudoparenchymatous exoperidium. The endoperidium contains both thick and thin-walled hyphae. The exoperidium often cracks as the sporing body expands and ripens and may form scales, warts or spines which may persist or fall off.


King Alfred's Cakes

Daldinia concentrica (King Alfred's Cakes) is an Ascomycete that grows as a parasite on Ash (Fraxinus excelsior) but can continue feeding on dead trunks and branches. It may occur rarely on other trees, such as Birch (Betula) and Gorse (Ulex). The sporing bodies are called stromata (sing. stroma) and in section each stroma consists of alternating concentric light and dark bands. The surface may be covered in a fine powder of asexual spores called conidia. In the outer layers, minute flask-like perithecia (sing. perithecium) develop, each lined by ascogenous hyphae: hyphae that develop into tiny cylindrical spore containers called asci (sing. ascus) each containing 8 sexual ascospores. The stroma acts as a water reserve for spore development and discharge. In many ascomycetes the spores are discharged explosively when the asci swell with water. due to this water reserve, detached stromata can continue to release spores for up to three weeks. Spore discharge is nocturnal, with a typical stroma releasing 10 million spores a night.


Above: Chondrostereum purpureum (Purple Bark Fungus) occurs on broadleaf trees, especially trees of the Rose family, such as Plum and Cherry (Prunus genus) but others too, including Salix (Willow) and Birch (Betula). Sometimes the fungus forms encrusting mats, but often it forms overlapping tiers of small brackets. The bases of the brackets in this case are partially encrusting at their bases, creating a curious morphology.

Chondrostereum is a basidiomycete bracket fungus that has   no pores.

This fungus causes silver-leaf disease. In this disease the leaves develop a silver sheen which results from separation of the epithelium from the underlying mesophyll (see leaf structure) and scattering of light by the resultant air spaces. This reduces photosynthesis and eventually kills the tree. The fungus does not actually infect the leaves, but rather it infects trees through wounds in the stem or branches and its hyphae reach the xylem where it obtains nutrients. It appears unable to digest the wood itself (since it does not secrete lignolytic enzymes but rather degrades cellulose and the pectin 'glue' that holds plant cells together). These enzymes released into xylem are responsible for the silvering of the leaves which eventually kills the tree. The sporing bodies of the fungus then develop on the dead tree.

Chondrostereum purpureum has been used as a biological control agent in forest plantations to control trees like Birch and Red Alder. This is a potentially risky strategy, ecologically speaking! A model of spore plume dispersal, which assumed a Gaussian dispersal curve, suggested that any susceptible tree within 500 m of a tree bearing sporing brackets is particularly vulnerable to infection and only trees more than 5000 m away were predicted to be exposed to natural background levels of spores and so at low risk. Conversely, it is considered a pest in fruit orchards.


De Jong, M.D. et al. 1990. Risk analysis applied to biological control of a forest weed, using the Gaussian plume model. Grana 29: 139-145.

Simpson, R.M. et al. 2001. Extracellular enzymes of Chondrostereum purpureum, causal fungus of silverleaf disease. New Zealand Plant Protection 54: 202-208.


Inonotus brackets

Shown here is Inonotus radiatus (Alder Bracket) an annual fungus with a porous lower surface which is parasitic on trunks of alder and occasionally on other trees such as Birch (as here). It is known by a number of alternative names (synonyms) including Mensularia radiata. Its brackets grow in tiers.

Inonotus brackets

Inonotus brackets

More jelly fungi

Above and below: The purple jelly fungus Ascocoryne. Eventually the lobes develop into disc or shallow cup-shaped structures on stalks. This fungus is an ascomycete.

Above: Ascocoryne (purple) growing with Hypoxylon (black).

Below: I am undecided on the species determination of this jelly fungus, since its morphology is a bit ambiguous. It is possibly in an early stage of development. However, it could well be the basidiomycete Tremella foliacea which occurs on dead and rotting branches and logs, mainly of broadleaf trees. The sporing bodies grow first as cushions which become twisted and contorted and then develop into leaf-like lobes arising from a common base and are solitary or occurring in small groups.


Boletes are perhaps easiest to find in tree-dense urban environments, for most boletes form mycorrhizal symbioses with trees (both coniferous and deciduous) and so can often be found growing beneath them. They resemble gilled toadstools and are basidiomycetes except the hymenium (spore-producing tissue) usually lines many tiny tubules that open beneath the cap via pores, rather than lining gills. They come in an impressive variety of colors and are often quite spectacular.

This urban boletewas truly impressive with the diameter of a dinner plate and a metallic bronze cap (which made photography difficult as the cap was very reflective) and pores opening on the yellow undersurface. This is probably Boletus impolitus (Iodine Bolete) which has a sour odour of iodine or phenol.  The diameter of the cap is between about 5 and 16 cm, height 5 to 10 cm and the stem diameter 3 to 5 cm. The skin of the cap often becomes cracked. This fungus can be found below broadleaf trees, especially oak, and is often found on mown grass (as here).

Although most boletes are edible, Satan's Bolete (Boletus satanus or Rubroboletus satanus) is highly toxic but also very beautiful. It's chalk-white cap can reach 25 cm in diameter and the undersurface (pores) and stem are more-or-less scarlet in color. (The stem is typically yellowish towards the top and the pores orange towards the margin). It forms mycorrhizal symbioses with oak and sweet chestnut and prefers calcareous soils.

Above: one from my old notes. This is a crude sketch but one intended to record the true colors. This is probably a species of Xerocomus.


Spectacular Rustgill

This spectacular toadstool was one of a group growing at the base of a tree stump and is Gymnopilus junonius (= Gymnopilus spectabilis) also known as Spectacular Rustgill. The cap is 5 to 20 cm in diameter (about 9 cm in this specimen, but still expanding) and varies in color from gold/yellow to orange with cinnamon-colored fibrous scales. It is either solitary or occurs in small clusters at the bases of tree-stumps, especially broadleaf trees but conifers too. It is a wood-rotting fungus, feeding on dead wood.

Spectacular Rustgill

Spectacular Rustgill is a large toadstool with firm, dense flesh but it is inedible and some forms in certain locales around the world contains hallucinogenic neurotoxins. this has earned it the alternative names of Laughing Gym/Jim/Jack.

Spectacular Rustgill

A view of the gills. Although large, this is a young specimen and the velum is still breaking away and leaving a ring around the stem. The robust stem of this species is 5 to 20 cm tall and up to 3 cm in diameter and bulbous-clavate.

Spectacular Rustgill

Spectacular Rustgill

Coral Fungi

Crested Coral fungus

Above: Clavulina cristata, the Crested Coral fungus (a basidiomycete). This species is common in coniferous woods, less so in broadleaf woods.

More Fungi - part 1

Article created: 16 Dec 2020