Gryphoemia
Henna has been used to adorn women for as long as 9000 years and in over 60 countries. In nearly all of those countries, the word for the plant and the body art is "henna" or variant of that word. "Henna" is a Semitic word, and is linguistically related to the word for "tenderness" or love and affection.
In India, there are 17 official languages, and many variants of the word for henna. In Gujerat, the word is transliterated "Mehandi". Most of Indian languages pronounce the word for henna with an aspiration between the "h" and the "n", but when these words were transliterated into English, this aspiration was lost, because of limitations in typefaces and not listening carefully. Transliterations of other Indian language words for henna include Mehendi, Mehandi, Mehindi, Mehedi, and Meh'ndi and Mehndi. All are equally correct because they are all different languages.
In every language, the word for the plant, lawsonia inermis, and the body art, are the same. Some packages of henna will have both Henna and Meh'ndi written on them to accommodate shoppers from different ethnic groups. Others have the older word "Henna-Mehndi" which is adapted from the 18th century Urdu and Farsi words for "Night of the Henna": "henna-bendi".