Boletus auripes

Description

Boletus auripes is a species of bolete fungus in the family Boletaceae. The defining features include the fine reticulation on the stem surface, the absence of any blue bruising or staining, and the yellow pore surface that becomes olive yellow with maturity. First described in New York in 1898, the fungus is found in eastern Asia, Central America, and eastern North America from Canada to Florida. It is a mycorrhizal species and typically grows singly, scattered, or in groups in association with oak and beech trees between June and November.

In North America, where it is relatively common, the range of the fungus extends from Alaska south to Mexico, and east to New York. In Central America, it has been recorded in Belize. The mushroom has also been recorded in Taiwan, China (including Yunnan, Sichuan, Guangdong, Kwangsi, and Hunan), and Japan. It was reported for the first time from the Russian Far East in 2008.

Common names: Butter Foot Bolete.

Mushroom Identification

1. Cap

   6-20 cm in wide and starts convex, eventually becoming broadly convex. It is dry and has a finely velvety or nearly smooth surface. When it is in the button stage, it is yellow-brown or golden in color, but it becomes brown or yellowish-brown as it matures and eventually fades in color.

2. Pore Surface

   The pore surface is ranging from yellow to brownish-yellow or olive. It does not bruise when touched. It has 2-3 pores per mm and tubes that are up to 2 cm deep.

3. Stem

   The stem is 5-12 cm long and up to 3 cm thick. It is finely reticulated and has a bright yellow, brownish-yellow color that can be discolored with age. It may be more or less equal in shape. When it is young it can have a swollen bottom half.

4. Flesh

   The flesh is yellow and not staining on exposure, but sometimes becomes deeper yellow.

5. Odor and Taste

   Not distinctive.

6. Spore Print

   Yellow-brown, sometimes with an olive tinge in a fresh print.

7. Habitat

   Mycorrhizal with hardwoods, especially oaks or laurel; growing alone, scattered, or gregariously; summer and fall; fairly widely distributed in eastern North America.

8. Chemical Reactions

   Ammonia yellowish or negative on cap and flesh; KOH negative or yellowish on cap and flesh; iron salts negative on cap and flesh.

9. Microscopic Features

   Spores 9.5-15 x 3.5-5 µ; smooth; subfusiform.

Look-Alikes

1. Boletus aureissimus

   Has a similar appearance, but has a honey-yellow to bright yellow or yellow-ochre cap, and less conspicuous stem reticulation.

2. Boletus aurantiosplendens

   Has a more variably colored cap that can be orange, brownish orange, or yellowish, and variable degrees of stem reticulation.

3. Boletus hortonii

   Has a similar color scheme but lacks reticulation on the stem.

4. Boletus lychnipes

   Known only from a limited area in the northern Cordillera de Talamanca. The latter species may be distinguished by the lack of reticulations on the upper half of the stem, a brown or salmon-pink staining reaction on the stem in response to handling, and microscopically by a conspicuously sterile margin and prominent pseudocystidia.

History

The species was originally described by American mycologist Charles Horton Peck in 1898. Peck collected the type specimen in Port Jefferson, New York.

In 1945, Rolf Singer proposed the variety Boletus auripes var. aureissimus as a new combination of the name Ceriomyces aureissimus described by William Alphonso Murrill in 1938; this taxon is now regarded as a distinct species under the name Boletus aureissimus.

In 1936, Wally Snell reported finding a specimen of Boletus crassipes, another species described by Peck from Mount Gretna, Pennsylvania.

In the genus Boletus, B. auripes is classified in section Appendiculati. Species in this section are characterized by having a dry cap with a surface texture ranging from smooth to somewhat tomentose, yellow flesh, a reticulate stem, and a mild taste. Other North American boletes in this section include Boletus speciosus and Boletus regius.

The specific epithet auripes means "golden yellow foot".

Video

Photo copyright:

All photos were taken by the Ultimate Mushroom team and can be used for your own purposes under the Attribution-ShareAlike 4.0 International license.