On my last trip to Iran we visited an amazing place in Yazd where they were producing henna literally the way they have done for hundreds of years. The atmosphere was nearly mystical, the smell so grassy and rich, the light soft and green from the henna dust.

These giant, stone wheels were once pulled by donkeys, now they are motorised.

This man was scooping the ground henna into canvas bags

Here the bags are sewn up. This mans white hair had taken up a reddish ting from the henna dust.

Henna has multiple traditional uses. It is known mostly  as a decorative dye for hair, hands and feet. It is also used for dying carpets and textiles.
Some of the famous Persian miniaturists applied henna as a colour in their work.
As a medicine you chew henna leaves for mouth ulcers and apply henna paste to minor burns
and inflammations . For headaches the paste is applied directly to the head.
As a hair dye you mix henna with green walnut shells ( dark brown ) , camomile ( blondish ),  coffee    ( brown ) and tea ( red ).