The genus Coffea is a member of the so-called coffee tree family, Rubiaceae, one of the largest plant families with approximately 13,200 species in ca 610 genera (Davis et al. 2009). Rubiaceae is divided into three subfamilies among which Ixorioideae hosts the (enlarged) tribe Coffeeae with 11 genera including Coffea (Davis et al. 2007).
Coffea comprises two subgenera, namely Coffea and Baracoffea (baracoffea alliance) with ca. 118 and 9 species, respectively (Davis et al. 2006). Most species of the subgenus Coffea are living in tropical Africa and on the neighboring islands (the Grande Comore, Madagascar, the Mascarenes). A few species, however, have 'colonized' Asia as shown on the related map. These are mostly taxa which have recently been transferred from Psilanthus to Coffea, due to both reconsideration of their morphology and marker-assisted phylogenetic analyses (Davis 2010, Davis 2011, Davis et al. 2011).
The subgenus Baracoffea is restricted to the dry forest of western Madagascar (Davis and Rakotonasolo 2008).
"Coffea can be characterized by a single synapomorphy, i.e. the presence of coffee beans: seeds with a deep groove on the ventral (flat) surface, the groove invaginated within the seed and appearing rolled/curled-over in transverse section." (Davies 2011)
The taxonomic history of this genus has been presented by Piet Stoffelen in his PhD thesis (Stoffelen 1998).
taxonomy & geography
Psilanthus mannii Hook.f. was the type species of the genus Psilanthus. It has been recently transferred to Coffea and is now Coffea mannii (Hook.f.) A.P. Davis.
the caffeine plants
