"In ancient times the valuable aromatic gum ladanum was gathered manually from Cistus creticus subsp. creticus, especially in Crete and Cyprus. The gum is exuded from glandular hairs on the leaves and young stems, especially under hot sunshine. It was gathered by allowing goats to graze on and among the plants; the ladanum adhered to their beards, which were then cut off. Alternatively a device called a ladanisterion or ergastiri, with long thongs of leather, was drawn over the plants by hand during the hottest part of the day, when the ladanum was at its runniest and stickiest..
The leather thongs became caked with ladanum, which was then scraped off and formed into lumps of various shapes. A very small amount of ladanum is still gathered in this traditional way in a small area surrounding a village in northern Crete."
http://www.cistuspage.org.uk/perfumery.htm
