noun
rocket larkspur
A flowering plant, Consolida ajacis, often grown ornamentally.
庭にヒエンソウが咲いている。
Rocket larkspur is blooming in the garden.
From the kanji 飛燕 (flying swallow) and 草 (grass/herb), referring to the flower's shape resembling a swallow in flight. The exact historical derivation is uncertain.