At least 12,000 species of resin-producing plants are recognized worldwide, of which around 500 are conifers while the rest are flowering plants. These aromatic plants belong to different families, among which is the Burseraceae, family, which includes the copales and cuajiotes.

The family includes 18 genera and hundreds of species documented since antiquity as major sources of resins and essential oils.

The genus Bursera

Copals belong to the genus Bursera, which has about 100 species distributed exclusively in the Americas.

Most of these plants are trees that measure between 4 and 12 m, although some reach up to 30 m, while others are shrubs of between 1 and 3 m in height. The crown is normally wider than the overall height.

All lose their leaves during the dry season of the year and flower at the end of it. Generally they are dioecious, i.e. the male and female flowers are produced by different individuals, and these develop prior to or at the same time as the new leaves.

Within Bursera, there are two natural groups or sections: the Bursera section, including the mulatos and cuajiotes, and the bullockia section, which includes the copals.

In the bullockia section, there are two distinct groups: copallifera and glabrifolia, with the latter being the most widely distributed group within Bursera.