noun
evening primrose; fragrant evening primrose
Sense 1 is the general term for evening primrose; sense 2 specifies Oenothera stricta. Both are common plant names.
庭にマツヨイグサが咲いている。
Evening primroses are blooming in the garden.
待宵草は夕方に花を開く。
Evening primroses open their flowers in the evening.
待宵 (matsuyoi, 'waiting for the evening') + 草 (kusa, 'grass/plant'), referring to its evening-blooming habit.