Studies on the systematic and ethnobotany of the subgenus Persea

Lauraceae is known to be a taxonomically "difficult" family (Kostermans 1952). The difficulties involve the lack of clear differences between most of the species (Allen, 1945; Kopp, 1966). For the subgenus Persea (the avocado genus) an additional feature increases the difficulties: the domestication or semi-domestication of some of its species. The main objective of this study was to do a systematic revision of the cultivated species of the subgenus. The area of distribution of the wild species of this subgenus is from northern South America to central Mexico. This area was also the site for the domestication of avocado. The co-existence of wild and cultivated varieties has been proposed (Williams, 1977) as one of the causes of the confusion in its classification. Due to its outbreeding system (Bergh, 1993), the species of Persea naturally are exchanging pollen between the wild and cultivated populations. These populations are the ones represented in Herbaria and living collections. This study will try to understand the factors that contribute to the variation of the wild and cultivated species of this subgenus. The hypothesis tested, was that the domestication of the species of Persea still is happening, and is the most important cause of the variation and taxonomic confusion. To test the hypothesis we need to know: the distribution of species, the history and pre-history of avocado cultivation, the uses and cultivation practices by present indigenous groups. This information could give a better elucidation of the relationships between these taxa to produce a more useful classification. The study is presented in two sections: Ethnobotany with data about the domestication of this species, and Systematic with a phenetic study using morphological and RAPD characters. Three new combinations are proposed. A discussion of the possible origin of the cultivation of avocado and how it affected the systematic of this group is presented.