On the presence of Cneorum (Cneoraceae) in Cuba: an example of biogeographic disjunction between the Mediterranean and the Caribbean?

Abstract

The main goal of the study was to shed light on the enigmatic world distribution of the Cneoraceae family, frequently, and until very recently, used as an example of the connection between the Mediterranean and the Caribbean floras. Specifically, we wanted to document the presence/absence of an endemic taxon, first collected in 1861 by Charles Wright from Cuba (Cneorum trimerum). During the last five years, we have visited all the localities where this taxon was originally collected, at Sierra Maestra in eastern Cuba, and revised all available herbarium material. Moreover, we checked all botanical and historical references, and also interviewed local people, to whom we showed pictures of the Mediterranean Cneorum. The conclusions of our survey are the following: i) nowadays, there are no Cneorum plants growing in their type localities in Cuba; ii) all the collected material from Cuba and deposited in herbaria by Wright, and also others studied by Carlquist, correspond unequivocally to C. tricoccon. The material collected by Ekman in 1922, and identified as C. trimerum, is sterile, and cannot be identified with certainty, however we think it is unlikely to be C. tricoccon; iii) this plant was probably introduced during the mid 19th century from Southern France, although it never become naturalized. The presence of French colonist settlements in coffee plantations in those areas where Cneorum was collected, together with the fact that the plant has medicinal properties, lead us to suggest that the colonist themselves were those introducing the plant in Cuba. Lastly, iv) Schoepfia stenophylla (Olacaceae) has also been recently misidentified as Cneorum tricoccon due to the resemblance of their leaves. Schoepfia stenophylla is an endemic species currently threatened and for which there is an in situ conservation plan. Such confusion between these species has contributed to the maintenance and spreading of the mistakes through the long taxonomic history of the presence of Cneorum in Cuba. Hence, we conclude that Cneorum can no longer be used as an example of biogeographical disjunction between the floras of the Mediterranean and the Caribbean.