Balsam is the resinous exudate (or sap), which forms on certain kinds of trees and shrubs. Balsam (from Hebrew bosem בֹּשֶׂם, "spice", "perfume") owes its name to the biblical Balm of Gilead.
Balsam is a solution of plant-specific resins in plant-specific solvents (essential oils). Such resins can include resin acids, esters, or alcohols. The exudate is a mobile to highly viscous liquid and often contains crystallized resin particles. Over time and as a result of other influences the exudate loses its liquidizing components or gets chemically converted into a solid material (i.e. by autoxidation).
Some authors require balsams to contain benzoic or cinnamic acid or their esters. Plant resins are sometimes classified according to other plant constituents in the mixture, for example as:
pure resins (guaiac, hashish),
gum-resins (containing gums/polysaccharides),
oleo-gum-resins (a mixture of gums, resins and essential oils),
oleo-resins (a mixture of resins and essential oils, e. g. capsicum, ginger and aspidinol),
balsams (resinous mixtures that contain cinnamic and/or benzoic acid or their esters),
glycoresins (podophyllin, jalap, kava kava),
fossile resins (amber, asphaltite, Utah resin).
Usually, animal secretions (musk, shellac, beeswax) are excluded from this definition.
Acaroid resin (Xanthorrhoea sp.)
Acouchi balsam (Protium sp.)
Ammoniacum
Asafoetida (Laser)
Balm of Gilead
Balm of Mecca
Balsam of Peru
Balsam of Tolu
Bisabol
Bdellium
Benzoin resin
Bukhoor
Cabreuva balsam (Myrocarpus frondosus, Myrocarpus fastigatus)
Camphor
Canada balsam
Chinese lacquer (Japanese lacquer)
Copaiba balsam
Copal
Corneiba balsam (Schinus terebinthifolius or Lithraea brasiliensis)
Damar
Dragon's blood (Calamus draco)
Elemi
Frankincense (Olibanum)
Galbanum
Guayac (Guaiacum officinale)
Guggul
Gurjun balsam
Imbauba balsam (Cecropia adenopus)
Labdanum
Mastic
Myrrh
Obira balsam (Apocynaceae)
Opopanax
Umiri balsam (Humiria floribunda)
Rosin (Colophony)
Sagapenum
Sandarac
Sarcocolla
Storax balsam
Turpentine
Venice turpentine (Larch turpentine) (Larix europaea)
Wallaba balsam (Eperua sp.)
Some balsams, such as Balsam of Peru, may be associated with allergies. In particular, Euphorbia latex ("wolf's milk") is strongly irritant and cytotoxic.