Inonotus radiatus
Description
Inonotus radiates is an apricot to rusty brown mushroom with slightly sunken reddish droplets near the margin when young, becoming browner, and eventually almost black with age. It has a yellow/white margin when young and rusty brown tubes. It is one of the smaller brackets and fruitbodies are nearly always tiered and also tend to merge one with another. The cap surface is finely velvety at first, becoming smoother with warty lumps and radial wrinkles.
Common names: Alder Bracket.
Inonotus radiatus Identification
Ecology
Saprobic on the deadwood of hardwoods; causing a soft white rot; annual; growing alone, gregariously, or in shelving clusters; summer and fall (or overwinter in warm climates); originally described from England; fairly widely distributed in North America from the Great Plains to the maritime provinces and through Mexico—and rare to occasional in the Pacific Northwest (primarily on alders); common in Europe.
Cap
3–8 cm across and 2–6 cm deep; semicircular to kidney-shaped in outline; often arranged in shelves and sometimes fused laterally with other caps; usually convex to planoconvex; very finely velvety when young, becoming bald with age; yellowish to orangish at first, becoming yellowish-brown to tan and eventually darkening to dark brown or black; often zoned; the margin thin and often wrinkled.
Pore Surface
Grayish to yellowish-brown when young, becoming darker brown; bruising brown when young and gray; with 3–4 angular pores per mm; tubes to 3 mm deep; with age becoming somewhat ragged and appearing "toothed."
Stem
Absent.
Flesh
Yellowish-brown to rusty brown; tough and stringy; faintly zoned.
Chemical Reactions
KOH black on flesh and cap surface.
Microscopic Features
Spores 5.5–7 x 3.5–4.5 µm; smooth; ellipsoid; hyaline to brownish in KOH; inamyloid or faintly dextrinoid. Hymenial setae scattered; 25–40 x 6–10 µm; fusoid; often with a swollen base. Setal hyphae absent. Hyphal system monomitic; hyphae thin- to thick-walled, 2–7 µm wide, smooth; hyaline to brown-walled; clamp connections not found.
Similar Species
Pseudoinonotus dryadeus produces larger brackets and weeps dark-honey-colored droplets much more copiously; it does not usually produce tiers of fruitbodies and it is found mainly on the basal roots and lower trunks of oak trees.
History
In 1799 British botanist-mycologist James Sowerby (1757 - 1822) described the Alder Bracket, giving it the binomial scientific name Boletus radiatus. It was in 1916 that Spanish mycologist Lázaro Ibiza (1858 - 1921) transferred this species to the genus Mensularia, establishing Mensularia radiata as what some mycologists (including the British Mycological Society) now accept as its preferred scientific name. Inonotus radiatus, the name that Finnish mycologist Petter Adolf Karsten (1834 - 1917) gave to the Alder Bracket in 1882, is the name you will find in most reference sources, however.
This species has several other synonyms including Xanthoporia radiata (Sowerby) Ţura, Zmitr., Wasser, Raats & Nevo, Boletus radiatus Sowerby, Polyporus radiatus (Sowerby) Fr., Fomes variegatus Secr., and Polystictus radiatus (Sowerby) Cooke.
Following a paper published in Israel in 2011, mycologists generally accept the renaming of this species as Xanthoporia radiata (Sowerby) Ţura, Zmitr., Wasser, Raats & Nevo.
Inonotus, the genus name of the Alder Bracket fungus, comes from ino- a prefix meaning fibrous, and or which means an ear; the ending -us merely turns it into the form of a Latinised noun.
The specific name radiatus comes from the Latin radi- meaning a ray, spoke, or plate, and it is probably a reference to the radial wrinkles that are often evident on the upper surfaces of mature Alder Brackets.
Photo sources:
Photo 1 - Author: Antti Salovaara (Public Domain)
Photo 2 - Author: Dominicus Johannes Bergsma (CC BY-SA 4.0)
Photo 3 - Author: dschigel (CC BY-SA 4.0)
Photo 4 - Author: Jerzy Opioła (CC BY-SA 3.0)
Photo 5 - Author: Dominicus Johannes Bergsma (CC BY-SA 4.0)
