What You Should Know
Fan-shaped to kidney-shaped structure; cap 2–12 in (5–30 cm) across and 1/4–1/2 in (0.5–1.3 cm) thick, reddish-brown but becoming paler towards the margin, upper surface densely hairy, especially towards the point of attachment; margin of cap incurved; gills closely spaced, dirty white to pinkish-brown or tan, edges of gills distinctly saw-toothed; spores creamy white in mass.
The saw-toothed gills are distinctive. Lentinellus vulpinus is very similar to Lentinellus ursinus but has a cap that is pinkish white and a stalk-like base at the point of attachment. Neither fungus should be collected for the table.
There are several other Lentinellus species and all are too bitter to be edible. My keys include only two of the more common and conspicuous species: Lentinellus micheneri and Lentinellus ursinus. The presence of amyloid spores distinguishes Lentinellus from the genus Lentinus.
Other names: Bear Lentinus.
Lentinellus ursinus Mushroom Identification
Saprobic; growing in groups or shelf-like clusters on the wood of hardwoods (and, very rarely, the wood of conifers); summer and fall; widely distributed in North America.
Up to 10 cm across; kidney-shaped to roughly semicircular; broadly convex, becoming flat or depressed; minutely hairy or velvety, at least over the inner 1/3; brown, cinnamon brown, or pale; the margin inrolled.
Close or nearly distant; the edges distinctively saw-toothed; whitish to pinkish.
Strongly acrid or peppery; odor not distinctive or a little spicy.
Spores 4-4.5 x 3-3.5 µ; elliptical; amyloid; very finely ornamented with warts and spines. Pleurocystidia rare; fusoid to sharply pointed. Gloeocystidia present; clavate.
Photo 1 - Author: Holger Krisp (Creative Commons Attribution 3.0 Unported)
Photo 2 - Author: Ron Pastorino (Ronpast) (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 3 - Author: Ron Pastorino (Ronpast) (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 4 - Author: Hamilton (ham) (Creative Commons Attribution-Share Alike 3.0 Unported)