Common name: Tender Nesting Polypore
Hapalopilus nidulans is a tan/ ochraceous polypore mushroom with white basidiospores. It is found growing on hardwoods or conifers during spring to fall and is a wood decaying saprophyte. The shelf-like fruiting body has no stem and is a convex kidney shape with fine hairs. Normal size is 5 to 15 cm across, 2-4 cm wide, and 1-4 cm thick. The pore surface and flesh are the same color as the pileus top. The flesh is soft/spongy and watery at first, but will dry tough and hard. Spores are white, elliptical/cylindrical, and smooth with sizes ranging from 3.5-5 × 2-3 µm. Pores are angular and 2-4 per mm. The hyphal system is monomitic with thick to thin walled generative hyphae that have clamp connections. Seasonality is annual, completing its fruiting in one season. One fun characteristic is that the flesh will turn a deep lilac purple when exposed to KOH.
It was formerly called Polyporus nidulans and a synonym is Hapalopilus rutilans.