wild giant butterbur
Refers to a wild variety of butterbur (Petasites japonicus), often found in mountainous areas. The cross-reference to 蕗 (ふき) indicates it is a type of butterbur.
See also: ふき
Refers to the plant Farfugium japonicum, also known as 石蕗 (つわぶき). This sense is distinct from the butterbur meaning and is a different species.
See also: つわぶき
Wild giant butterbur is often seen in mountainous areas in spring.
Japanese silverleaf, like 石蕗, is a plant in the Asteraceae family.
Compound of 山 (やま, 'mountain') and 蕗 (ふき, 'butterbur'), referring to the wild mountain variety. The second sense is an extended use for a different plant, likely due to similar leaf shape or habitat.