gardenia
梔 refers specifically to the gardenia plant, a flowering shrub known for its fragrant white blossoms.
梔 combines 木 (tree) with 巵, which likely contributes the sound. The character was created to name the gardenia plant.
The tree radical 木 beside 巵 suggests a specific tree or shrub. Picture a gardenia bush with its glossy leaves and white flowers.
For シ, imagine a gardenia bush shaped like the letter 'C': C -> シ, and the bush is full of fragrant blossoms.