Pluteus leoninus

Description

Pluteus leoninus is recognized by a velvety-textured, yellowish-brown cap, free pinkish gills, and pallid stipe. It fruits sporadically, rare in some years, but can be fairly common in warm, wet years. Occasionally be found growing on dead wood in Europe and North Africa. The underside of the cap is typical of the genus Pluteus — the gills are pale, soon becoming pink when the spores ripen. But the upper surface is a bright tawny or olivaceous yellow. The species name leoninus (meaning leonine) refers to this cap color.

Recent molecular data shows that Pluteus flavofuligeneus is con-specific with P. leoninus, an older European name.

Common names: Lion Shield.

Mushroom Identification

1. Ecology

   Saprobic, growing alone or scattered on decaying hardwood logs and debris, or growing terrestrially; causing a white rot; late spring, early summer and fall east of the Rocky Mountains, overwinter on the West Coast; widely distributed in North America.

2. Cap

   3-5 cm; convex or bell-shaped at first, becoming broadly convex or nearly flat, but often retaining a broad central bump; finely velvety to silky, especially over the center; golden to dull or brownish yellow, with a brownish center; the margin not lined.

3. Gills

   Free from the stem or nearly so; close or crowded; short-gills frequent; whitish at first, becoming pink.

4. Stem

   5-9 cm long; up to 0.5 cm thick; tapering slightly to apex; bald or finely silky; whitish to yellowish or brownish; becoming hollow; basal mycelium white.

5. Flesh

   Thin; white; unchanging when sliced.

6. Chemical Reactions

   KOH negative on cap surface.

7. Spore Print

   Pink.

8. Microscopic Features

   Spores 5.5-7 x 5-6 µ; subglobose to broadly ellipsoid; smooth; ochraceous in KOH; inamyloid. Pleurocystidia widely lageniform, subutriform, or subsaccate; thin-walled; occasionally with one or two small hooks; hyaline in KOH; scattered; to 100 x 28 µ. Cheilocystidia fusiform or narrowly lageniform; thin-walled; hyaline in KOH; often abundant; to 65 x 12 µ. Pileipellis a cutis. Clamp connections absent.

Look-Alikes

1. Pluteus cervinus

   Usually larger and has a smooth brown or fawn cap.

2. Pluteus chrysophaeus

   Has a bright yellow cap but it is usually much smaller than Pluteus leoninus and does not have a darker central region. And its non-velvety cap, without brown shades.

History

This woodland mushroom was described in 1762 by German naturalist Jacob Christian Schaeffer, who gave it the binomial scientific name Agaricus leoninus. It was another German mycologist, Paul Kummer, who in 1871 transferred this species to its current genus, renaming it Pluteus leoninus, which is the scientific name by which mycologists generally refer to the Lion Shield to this day.

Synonyms of Pluteus leoninus include Agaricus leoninus (Schaeff.), Agaricus sororiatus P. Karst., and Pluteus sororiatus (P. Karst.) P. Karst.

Pluteus, the genus name, comes from Latin and means a protective fence or screen - a shield for example. The specific epithet leoninus simply means 'like a lion', a reference to the color rather than any other features of this rare woodland fungus!

Photo sources:

Photo 1 - Author: Strobilomyces (CC BY-SA 2.5)

Photo 2 - Author: Jerzy Opioła (CC BY-SA 4.0)

Photo 3 - Author: caspar s (CC BY-SA 2.0)

Photo 4 - Author: Tatiana Bulyonkova from Novosibirsk, Russia (CC BY-SA 2.0)