Wood hedgehog or Fused polypore

Cap up to 15 cm across, up to 3 cm thick. Yellowish in young mushrooms, turning red or orange with time — an intense color that is hard to mistake. The surface is dry; caps often fuse together.

The cap is 4-15 cm across, irregular, with an unevenly wavy margin; convex in young mushrooms, flat and spread out in mature ones, with a lumpy surface and a depressed center. The color is ivory, cream, ochre-yellow to light orange, turning reddish-brown in old mushrooms. The surface is dry and silky-suede, slightly sticky in wet weather. The cap skin is thin and peels easily.

Tubular pore surface. Tubes short, 1–3 mm long. White at first, browning with time. Spore print white.

The spiny hymenophore is the key diagnostic feature. Under the cap there are densely packed thin, pointed spines 3-6 mm long that break off easily. The spines are white to cream, yellowing with age and turning reddish-ochre in old mushrooms. The spore print is white.

Up to 10 cm tall. The young stem is white, then gets covered with rusty spots and takes on the cap’s color as it ages. Central, with no ring and no volva.

The stem is 3-8 cm tall and 1-3 cm thick, cylindrical, often widening toward the base, sometimes eccentric (off-center from the cap). It's white to cream, yellowing slightly where pressed. The surface is smooth, with no ring. The stem flesh is firm, becoming spongy in old mushrooms.

Firm, fleshy, white when cut. It has a slightly bitter taste that disappears after brief boiling.

The flesh is thick, white, firm and brittle. When cut, it slowly turns pale ochre (a slight yellowing). Young mushrooms have a delicate, pleasant nutty flavor; mature ones have a slightly bitter aftertaste that disappears after brief boiling.

Mushroomy, pleasant, not sharp. No chemical or unpleasant notes.

A faint, pleasant mushroomy-fruity aroma with a note of fresh nuts. The taste is mild and delicate; slightly bitter in old mushrooms.