The yerba mate is an evergreen tree from the family of Aquifoliaceae. It usually grows 6-8 meters (19 - 26 ft) but it can reach up to 18 m (59 ft) in height. Its oval leaves are 12 cm (5 inches) long, dark green at the top and lighter green at the bottom, with serrated edges. Yerba mate is in bloom between October and December and has an inflorescence/cluster of small, white flowers. The fruit is red or dark brown, 5-8 mm ( ¼ inch) in diameter and appears between March and June. Each fruit has 4-5 yellow seeds with hard husk. The seeds are scattered by birds. Many seeds which appear to be ripe have no more than a fraction of an embryo which means that the germinating period may be quite long.
The yerba mate tree comes from South American countries such as northern Argentina, southern Brazil, Paraguay and Uruguay. Commercially it is farmed mainly in Brazil, and to a lesser extent in Argentina and Paraguay.
There are two varieties of yerba mate: Ilex paraguariensis var. paraguariensis (the leaves and twigs of this tree are used for yerba mate) and Ilex paraguariensis var. vestita (this tree is densely pubescent and has no commercial use). Both types may be found in some regions of north-eastern Argentina and Brazil.
The yerba mate is a sub-tropical plant. It grows in areas where the annual rainfall is no less than 1200 mm, out of which at least 250 mm has to be in winter, which is the driest season. The minimum required temperature is -6 °C. The yerba mate tree can withstand the frequent snow falls in the mountainous regions in which it grows. The tree grows near rivers and springs and requires acid soil with a pH of 5.8-6.8.
Yerba mate can be propagated through seedlings and seeds. It is relatively difficult to secure rooting on a shoot/ seedling. Yerba mate seeds have to be sewn immediately or they must be pre-treated by stratification, otherwise they will lose the ability to germinate. If kept at a temperature of 5 °C, they will keep a low ability to germinate (1.7 do 6.6%) for 11 months. The relatively short life of the seeds and the low ability to germinate makes propagation of yerba mate quite problematic.