noun
blackening brittlegill (Russula nigricans)
A specific mushroom species; the name is a technical/common name in Japanese mycology.
クロハツは傷つくと黒く変色するキノコだ。
The blackening brittlegill is a mushroom that turns black when damaged.
The name クロハツ literally means 'black russula', from 黒 (black) and ハツ (russula mushroom). The exact derivation is uncertain, but it likely refers to the mushroom's blackening flesh.