さんかくそうじゃなかったです
三角草じゃなかったです
sankakusōjanakattadesu

Noun
Desu Copula

The polite, past negative form of みすみそう

1. Wasn't a triangle grass.; Wasn't triangular grass.

Past/Perfective
Negative
Polite
Casual Register
Usually Written in Kana