noun
sow thistle; milk thistle
Refers to the plant Sonchus oleraceus, a common weed with yellow flowers. The name literally means 'spring field mustard'.
See also: 野芥子
道端に春の野芥子が咲いていた。
Sow thistles were blooming by the roadside.
野芥子 is a more general term for sow thistle, while 春の野芥子 specifically refers to the spring-blooming species Sonchus oleraceus.
Compound of 春 (spring) + の (possessive particle) + 野芥子 (sow thistle). The name distinguishes this spring-blooming species from other sow thistles.