Henna is an ink made from the henna plant, most often used for temporary tattooing or body art. Henna was often used among the Jews in North African countries for vanity as well as ceremonial purposes.
Today henna is commonly used in Sephardi/Mizrahi Jewish pre-wedding bridal celebrations, with different designs symbolizing icons meant to protect the bride. Demons and evil spirits are supposed to be driven away by disguising the couple with intricate ink designs that may last weeks on the wedding couple’s skin.
The henna ceremony takes place toward the end of the couple’s wedding party, once the bride has put on her last set of clothes before she gets married. The oldest member of the family, usually the grandmother, spreads henna on the palms of the bride and groom. The henna is then wrapped against the skin to lock in body heat, creating a more intense color. Guests are sometimes encouraged to spread henna on their palms afterward as a symbol of good luck.
http://www.hennabysienna.com/jewish-henna.html
http://www.jewishjournal.com/weddings/article/henna_party_adds_colorful_touch_to_the_happy_couple_20080411
