Gomphus clavatus is an edible species of fungus in the genus Gomphus, family Gomphaceae. It is commonly known as pig's ears, alluding to the violet underside and yellowish cap of the fruit bodies. Other common names for this species include clustered chanterelle and violet chanterelle. Typically found in coniferous forests of the northern hemisphere, G. clavatus is mycorrhizal, and is associated with tree species in a variety of coniferous genera, particularly spruces and firs. It may be identified by its orangish-brown to lilac color, its purple, wrinkled hymenium, and the unique shape of its fruit bodies.
In the 18th and 19th centuries, G. clavatus was the only recognized Gomphus species, the type species for the genus. The species name is derived from the Latin word clavi (club) and means "club-shaped". In 1798, mycologist Christian Hendrik Persoon first described G. clavatus as Merulius violaceus, the species name referring to the purple-colored hymenium. British botanist Samuel Frederick Gray transferred the species to the genus Gomphus in 1821.G. clavatus was later assigned to Cantharellus by Elias Magnus Fries in 1821, and even later (1886) to Nevrophyllum. Research combining the use of phylogenetic analyses of DNA sequences and more traditional morphology-based characters has resulted in a reshuffling of the species concept in Gomphus; as a result, G. clavatus is currently considered the only Gomphus species in North America.
The basidiocarps, or fruit bodies, of immature Gomphus clavatus are club-shaped and have one cap or pileus, but later spread out and have a so-called merismatoid appearance—several vase-shaped caps rising from a common stem. The fruit body is up to 15 cm (5.9 in) wide and 17 cm (6.7 in) tall, fan-shaped with wavy edges. The upper surfaces of the fruit bodies are covered with brown hyphae that form small, distinct patches towards the margin, but combine to form a continuous felt-like tomentum over the center of the cap. The color of the upper cap surface is orange-brown to violet, but later in age fades to a lighter brown. The lower spore-bearing surface, the hymenium, is wrinkled, often with folds and pits, and violet to brown in color. The stem, which is continuous with the cap, is 1–3 cm (0.4–1.2 in) wide, solid, and covered with fine hairs (tomentum) that become more coarse (hispid) towards the base. It is often compound, with several fruit bodies arising from the basal portion. Fruit bodies may bruise reddish-brown where handled. The flesh is whitish-pink to lilac. The taste and odor are mild. The spore print is yellow to orange-yellow.
Basidiospores are elliptical, wrinkled or slightly warted, and 10–14 by 5–7.5 μm. The spores are nonamyloid, meaning they have a negative color reaction with the iodine in Melzer's reagent. The spore-bearing structures, the basidia, are elongated or club-shaped, hyaline (glassy or translucent), and four-spored, with dimensions of 60–90 by 8.5–11.5 μm.G. clavatus does not contain cystidia, the sterile cells associated with basidia in many species. Clamp connections are present.
Habitat, distribution, and conservation
This species grows singly or in clusters on the ground, typically in coniferous forests, and with a preference for deep leaf litter in moist, shady areas. It is more common at elevations of greater than 2,000 ft (610 m).Gomphus clavatus has been reported as forming symbiotic (mycorrhizal) associations with a variety of trees: Abies alba,Abies firma,Abies nephrolepsis,Abies religiosa,Picea species,Pinus densiflora,Pseudotsuga menziesii, and Tsuga heterophylla. It is also reported with beech (Fagus sylvatica) in Europe.
Gomphus clavatus has been reported from Austria,Canada, China, the Czech Republic,France, Germany, Greece, Italy,Japan, Lithuania,Korea,Mexico,Pakistan,Poland,Romania,Russia,Sweden,Switzerland,Turkey, and the USA.
In Europe, Gomphus clavatus appears on the national Red Lists of threatened fungi in 17 countries and is one of 33 species proposed for international conservation under the Bern Convention. Due to a substantial decline in sightings,Gomphus clavatus became a legally protected species in Hungary on September 1, 2005. It also has legal protection in Slovakia and Slovenia. The species formerly occurred in England, but has not been seen since 1927 and is now regarded as extinct. The fungus faces loss and degradation of its habitat; eutrophication is another potential threat.
Gomphus clavatus is edible (and rated as choice by some), although like many edible fungi, consumption may cause gastrointestinal distress in susceptible individuals. The flesh becomes bitter with age. It has been used for cooking for some time — Elias Magnus Fries included it in his 1867 book Sveriges ätliga och giftiga svampar (Edible and Poisonous Mushrooms in Sweden).
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