prickly sow-thistle; spiny sow thistle
A common weed with spiny leaves and yellow flowers, often found in disturbed areas. The name literally means 'demon's field mustard'.
A lot of prickly sow-thistles are growing by the roadside.
The leaves of the prickly sow-thistle have sharp spines.
ノゲシ (Sonchus oleraceus) is a similar but less spiny sow-thistle species; オニノゲシ is distinguished by its prickly leaves.
Katakana spelling is common for plant names and is the usual written form for this word.
Kanji spelling is rare and may not be widely recognized; the katakana form is strongly preferred.
Compound of 鬼 (oni, 'demon') + の (no, possessive particle) + 芥子 (keshi, 'poppy' or 'mustard'), literally 'demon's field mustard'. The name likely refers to the plant's fierce, spiny appearance.