Rhodotus palmatus

Description

Rhodotus palmatus is a rare stunning mushroom with a highly reticulated cap and bright orange/pink coloration. It has an affinity for freshly felled hardwoods. Many specimens are found fruiting from elm trees, with a lesser occurrence found on horse chestnut, basswood, and maple. Many species that specialize on freshly fallen trees tend to be latently present within the wood. Spores of latently present saprotrophs that land on a living suitable host tree can live in a dormant state within the tree for several years until the plant finally dies. Rarely grows on dead wood of deciduous trees, especially on fallen trunks and branches of elms (Ulmus) in scree and floodplain forests. The smell is strong, pleasant, and fruity. With age, the cap spreads out and the color becomes paler. The white-veined network is not always present. Rhodotus palmatus is not poisonous, but it is inedible and doesn't have any psychedelic effect.

Rhodotus palmatus is found in several countries of northern and central mainland Europe including the Scandinavian countries as well as Germany, Poland, and Italy. This remarkable mushroom is also reported in parts of Asia and North America. It tends to fruit in cooler and moister weather, from spring to autumn in the United States, or autumn to winter in Britain and Europe.

Rhodotus palmatus is a candidate species in over half of the European fungal Red Lists, and is listed as critically endangered or near threatened in 12 countries. In the Baltic countries Estonia, Latvia, and Lithuania, it is considered by the Environmental Protection Ministries to be regionally extinct, reported as "extinct or probably extinct". It was one of 35 fungal species to gain legal protection in Hungary in 2005, making it a fineable offense to pick them.

Common names: Wrinkled Peach, Netted Rhodotus, Rosy Veincap, Zalmzwam (Netherlands), Hlívovec Ostnovýtrusný (Czech Republic), Żyłkowiec Różowawy (Poland), Ferskenhat (Denmark), Gyslotoji kremzliabudė (Lithuania), Roosa võrkheinik (Estonia), Ferskenpote (Norway), Ådermussling (Sweden), Orangerötlicher Adernseitling (Austria), Vēdekļa sārtaine (Latvia).

Mushroom Identification

1. Cap

   2-9 cm; convex with an incurved margin when young, becoming broadly convex or flat; slimy and gelatinous; conspicuously netted with whitish ridges and veins - or without veins and ridges; salmon to pinkish-orange.

2. Gills

   Attached to the stem; close; whitish when young, becoming pink to salmon from spores.

3. Stem

   1.5 to 5 cm long; up to 1 cm thick; pinkish; slightly hairy; often off-center; tough.

4. Flesh

   Pinkish; rubbery and gelatinous.

5. Spore Print

   Pinkish.

6. Microscopic Features

   Spores 5–7.5 x 4–7.5 µm (including ornamentaion); subglobose to broadly ellipsoid; spiny with rod-like spines 0.5–1 µm long; hyaline in KOH; inamyloid. Basidia 30–37.5 x 6–7.5 µm; subclavate; 4-sterigmate. Cheilocystidia 30–55 x 2.5–5 µm; fusiform to narrowly lageniform; smooth; thin-walled; hyaline in KOH. Pleurocystidia not found. Pileipellis an easily disarticulating hymeniform layer of clavate elements 28–38 x 7.5–12.5 µm, smooth, hyaline in KOH—interspersed with cystidioid elements 25–75 x 5–7.5 µm, fusiform to lageniform or irregular, smooth, hyaline in KOH.

7. Habitat

   Saprobic; growing alone, scattered, or (more commonly) in troops on the wet, well-decayed wood of hardwoods; late spring through fall; widely distributed east of the Great Plains.

Rhodotus palmatus Antimicrobial Activity

As part of a Spanish research study to evaluate the antimicrobial activity of mushrooms, Rhodotus palmatus was one of 204 species screened against a panel of human clinical pathogens and laboratory control strains. Using a standard laboratory method to determine antimicrobial susceptibility, the mushroom was shown to have moderate antibacterial activity against Bacillus subtilis, and weak antifungal activity against both Saccharomyces cerevisiae and Aspergillus fumigatus.

History

The type species of genus Rhodotus was originally described as Agaricus palmatus in 1785 by French botanist Jean Bulliard. Later mycologist Elias Magnus Fries included it under the same name in his Systema Mycologicum. It was transferred to the then newly described genus Rhodotus in a 1926 publication by French mycologist René Maire.

The specific epithet is derived from the Latin palmatus, meaning "shaped like a hand" — possibly a reference to the resemblance of the cap surface to the lines in the palm of a hand.

Synonyms

• Pleurotus subpalmatus, Claude Gillet, 1876

• Agaricus alveolatus, Cragin, 885

• Agaricus palmatus Bull. (1785)

• Agaricus palmatus var. sessilis Berk. (1859)

• Agaricus phlebophorus var. reticulatus Cooke (1886)

• Agaricus reticeps, Montagne, 1856

• Agaricus reticulatus, Johnson, 1880

• Agaricus subpalmatus Fr. 1838

• Crepidotus palmatus (Bull.) Gillet, 1876

• Dendrosarcus subpalmatus (Fr.) Kuntze 1898

• Entoloma cookei Richon 1879

• Gyrophila palmata (Bull.) Quél. 1896

• Lentinula reticeps, William Alphonso Murrill, 1915

• Panus meruliiceps, Peck 1905

• Pleuropus palmatus (Bull.) Gray, 1821

• Pleurotus pubescens, Charles Horton Peck, 1891

• Pleurotus subpalmatus (Fr.) Gillet 1874

• Pluteus alveolatus, Saccardo, 1887

• Rhodotus palmatus forma cystidiophorus Maire 1932

• Rhodotus palmatus forma palmatus (Bull.) Maire 1926

• Rhodotus subpalmatus (Fr.) S. Imai 1938

Photo sources:

Photo 1 - Author: squirrely (CC BY-SA 4.0)

Photo 2 - Author: squirrely (CC BY-SA 4.0)

Photo 3 - Author: squirrely (CC BY-SA 4.0)

Photo 4 - Author: Dan Molter (shroomydan) (CC BY-SA 3.0)

Photo 5 - Author: Dan Molter (shroomydan) (CC BY-SA 3.0)