PHYLOGENY AND GEOGRAPHIC HISTORY OF ANNONACEAE

Whereas Takhtajan and Smith situated the origin of angiosperms between Southeast Asia and Australia, Walker and Le Thomas emphasized the con centration of primitive pollen types of Annonaceae in South America an d Africa, suggesting instead a Northern Gondwanan origin for this fami ly of primitive angiosperms. A cladistic analysis of Annonaceae shows a basal split of the family into Anaxagorea, the only genus with an As ian and Neotropical distribution, and a basically African and Neotropi cal line that includes the rest of the family. Several advanced lines occur in both Africa and Asia, one of which reaches Australia. This pa ttern may reflect the following history: (a) disjunction of Laurasian (Anaxagorea) and Northern Gondwanan lines in the Early Cretaceous, whe n interchanges across the Tethys were still easy and the major lines o f Magnoliidae are documented by paleobotany; (b) radiation of the Nort hern Gondwanan line during the Late Cretaceous, while oceanic barriers were widening; (c) dispersal of African lines into Laurasia due to no rthward movement of Africa and India in the Early Tertiary, attested b y the presence of fossil seeds of Annonaceae in Europe, and interchang es between North and South America at the end of the Tertiary.