Boyd’s Bible Dictionary:
The gum of the camphor-tree. But in Song of Sol. 1:14; 4:13; the Cyprus flower or henna.
Concise Bible Dictionary:
Lawsonia Inermis
A shrub whose flowers grow in bunches having a very sweet smell (Song of Sol. 1:14; Song of Sol. 4:13). The Hebrew name is kopher, and the Arabs call it henna. A powder made of the leaves and flowers is mixed with water and used by the women to color the nails of their hands and feet.
Henna