Steccherinum ochraceum
Description
Steccherinum ochraceum is a hydnoid fungus of the family Steccherinaceae. It is a plant pathogen infecting sweetgum trees. Identification is more certain when both caps and crustlike spreading portions are present.
The orange-yellow or ochre-colored caps of this fungus have a whitish margin. The caps are often hairy, zoned and may occur in overlapping clusters. The undersurfaces of the caps and the crustlike resupinate portions are covered by ochre-colored spines up to 1.5 mm long and often forked at their tips.
Common names: Spreading Tooth.
Mushroom Identification
Ecology
Saprobic on the deadwood of hardwoods and, rarely, conifers; growing alone or gregariously on sticks, logs, or stumps; causing a white rot; late spring through fall (or overwinter in warmer climates); widely distributed in North America, but more common east of the Rocky Mountains.
Fruiting Body
Variable; usually a patch of densely packed spines up to about 3 cm across, with folded-over edges (especially when growing on logs and sticks) - but sometimes with a well-defined cap and even, at times, a stem (especially when growing on stumps).
Upper Surface
When present grooved and hairy to velvety; with more or less concentric zones of color and texture; grayish to brownish or whitish; margin white, scalloped.
Undersurface
Composed of densely packed spines up to 3 mm long; orange, fading to yellowish or brownish when old; drying to dull salmon in herbarium specimens.
Stem
When present up to 8 mm long and 2 mm wide; colored like the upper surface.
Flesh
Tough; leathery; whitish.
Odor and Taste
Not distinctive.
Chemical Reactions
KOH negative on all surfaces.
Spore Print
Undocumented, but probably white.
Microscopic Features
Spores 3.5-5 x 2-2.5 µ; smooth; ellipsoid; inamyloid; hyaline in KOH. Skeletocystidia cylindric to subfusiform; 4-10 µ wide; arising from the spine trama and usually projecting beyond the basidia; thick-walled; usually substantially encrusted. Context dimitic.
History
In 1799, when Christiaan Hendrik Persoon described this toothed (hydnoid) fungus he gave it the binomial scientific name Hydnum ochraceum - a name which may have already been applied to this species by German naturalist Johann Friedrich Gmelin (1748 - 1804).
This fungus species was transferred to the genus Steccherinum in 1821 by British mycologist Samuel Frederick Gray (1766 - 1828).
Synonyms of Steccherinum ochraceum include Hydnum ochraceum Pers., Hydnum denticulatum Pers., Hydnum pudorinum Fr., Acia denticulata (Pers.) P. Karst., and Mycoleptodon ochraceum (Pers.) Pat.
Steccherinum, the genus name, was established in 1821 by British mycologist Samuel Frederick Gray. The specific ochraceum is a reference to the ochre (orange-yellow) color typical of this species.
Photo sources:
Photo 1 - Author: Nina Filippova (CC BY-SA 4.0)
Photo 2 - Author: dschigel (CC BY-SA 4.0)
Photo 3 - Author: Garrett Taylor (CC BY-SA 4.0)
Photo 4 - Author: Michel Langeveld (CC BY-SA 4.0)
Photo 5 - Author: Garrett Taylor (CC BY-SA 4.0)
