Gums and resins
Gums are formed from the breakdown of cellulose in the plant cell walls, normally when they are damaged. They have long been used as adhesives but have a wide range of modern uses.
Gum arabic has been traded for hundreds of years. It is harvested from Acacia trees, especially those originating in North Africa. The tree is wounded with a hatchet to make the gum flow. Then the bark is stripped from the tree, the hardened gum is collected, cleaned and ground into a fine powder. This is used as an adhesive on postage stamps, and to thicken medicines and ink.
Resins are secreted from specialised structures in a wide range of plants. They are aromatic and flammable, and so have traditionally been used in torches, embalming, incense and medicines.
For example, resins from the Peru balsam (Myroxylon balsamum) are traditionally used to treat asthma, rheumatism, and as an antiseptic. Today they are used commercially as an aromatic addition to soaps, cosmetics and perfumes.
Pine resins are used to waterproof ships made of timber, and are refined to produced turpentine.
Amber is formed from fossilised resins. Myrrh, mentioned in the Bible and used for thousands of years in the Middle East, is made from the resin of Commiphora myrrha.