Jelly Fungi

Jelly Fungi ( a group of fungi related to gilled mushrooms and collectively classified within the Tremellales order) differ from most other fungi in that the fruiting body takes on radically different forms depending on atmospheric conditions. During dry conditions, the fruiting body forms a tough but thin flat layer  that binds tightly to the substrate (usually dead wood) and is difficult to separate from it. Superficially the jelly fungi may appear as a  layer of paint  on the substrate (see photo).

Dry state of Exidia glandulosa found on the (right) branch of a dead maple twig. the left branch has visible bark.

Dry state of Exidia glandulosa found on the (right) branch of a dead maple twig. The left branch has visible bark and no Exidia.

During and shortly after rain, the jelly fungus absorbs water, enlarges and becomes a slippery, soft or gelatinous mass. In this stage, microscopic spores are produced in large numbers and are available for wind and rain dispersal. The distinctive texture of the Tremellales and related forms, some of which are brightly colored, gave rise to colorful colloquial names such as “witch’s butter” and “apricot jelly mushroom”. Photographs of three species which occurred in my yard in the past year are shown.
Exidia glandulosa (Black witch’s Butter) occurs as what appears to be little more than a black stain on the bark of a dead oak branch. A rain event in May 2013 converted the fungus to a grey to almost black, swollen and gelatinous mass that envelops the twig over nearly a foot (30 cm) in length. No stalk is produced so the mass remains tightly bound to the wood. When the weather dries, the fungus reverts to its dry state awaiting another wet interval when it will again take on the hydrated condition. This species was found in the yard again in 2014.

Close-up of hydrated colony of Exidia on an oak branch. Diameter (including fungus) is about 4 cm (1.5 inches).

Close-up of hydrated colony of Exidia on an oak branch. Diameter (including fungus) is about 4 cm (1.5 inches).

A second brownish specimen also was found. (see photo) It is unclear whether this belongs to a different species.

Another Exidia specimen, which is brown when hydrated.

Another Exidia specimen which is brown when hydrated.

Tremella is a genus of jelly fungi found world-wide in which, depending on species, the fruiting body, after absorbing water, consists of soft gelatinous lobes or multiple infoldings resembling somewhat a flower with multiple petals, while others form a simple unlobed rubbery blob.The group is especially interesting because it appears that most species of the genus (if not all, according to some observers)  are parasitic on the mycelia or, less often, on the fruiting body of unrelated wood-decaying (saprophytic) fungi such as members of the genus Stereum. The Tremella genus is found world-wide and over 100 species are recognized.
Tremella mesenterica– “witch’s butter”- first photographed on Aug. 2011, established on a dead oak twig. In the hydrated state the fruiting body appears purple. In the photograph, the fungus shares a twig with lichens which presumably colonized the twig when it was  attached to the tree and  still alive.

Hydrated state of a Tremella species, presumably T. mesenterica.

Hydrated state of a Tremella species, presumably T. mesenterica.

T. fuciformis with a highly convoluted fruiting body, is whitish and somewhat translucent. My specimen became dull yellowish when mature, losing its translucency. This species, based on my specimen, retains moisture and therefore flabbiness long after rains pass. It was photographed on the trunk of a long dead red maple left standing in our front yard.

Tremella fuciformis growing on an upright maple trunk. The fungus is about 8 cm across.

Tremella fuciformis growing on an upright maple trunk. The fungus is about 8 cm across.

The natural range include the southern U.S. states and tropical areas. The specimen was photographed in July 2013 and lasted several months. This species is cultivated for food (although considered rather tasteless by itself) and as an ingredient in traditional medicines in parts of Asia, especially China.

The same T. fuciformis, a few weeks older.

The same T. fuciformis, a few weeks older. New growth is on the right side.

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