lawsonia

from The Century Dictionary.

• noun A genus of polypetalous shrubs, consisting of a single species, L. inermis, the celebrated henna-plant of the East. See henna.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) An Asiatic and North African shrub (Lawsonia inermis), with smooth oval leaves, and fragrant white flowers. Henna is prepared from the leaves and twigs. In England the shrub is called Egyptian privet, and in the West Indies, Jamaica mignonette.