BIOGEOGRAPHY OF THE FAMILY MIMOSACEAE IN SRI LANKA

Abstract

The objective of the present study was to investigate the geographical distribution of theMimosaceae family In Sri Lanka. Some primary data for the study were obtained during fieldvisits to different places, through personal communications with Ayurvedic doctors and residentsof different geographical areas. Also incorporated were secondary data and information formseveral sources. The distribution of each genus and species was mapped by a GIS to show theirdistribution on a district basis, As the study revealed, the Family Mimosaceae contains ]6Genera (none of them endemic).~ine are indigenous (although they contain some exoticspecies); Acacia. Abarema, Aden mthera, Albizia, Cathormion, Dischrostachys, En tada ,Neptunia and Painteria .The remaining seven genera are exotic; Desmanthus, Leucaena,Mimosa, Pithecellobium, Prosopis. Famanea and Vachellia.

The genera Acacia. Albizzia and Mimosa can be considered widely occurring in all zones.Cathormion and Prosopis are confined to the arid zone. Dischrostachys and Pithecllobium are inthe dry and wet zones. Desmanthus. Vachellia, Neptunia and Painteria are confined to the dryzone. Entada, Leucaena, and Samanea are in the dry and intermediate zones. Abarema andA denanthera in the intermediate and wet zones. Acacia is the genus having the largest number ofspecies (19), followed by Albtziatb). Both Abarema and Mimosa contain three species each.Adenanthera and Neptunia have 2 species each. The remaining 10 genera have one species ineach genus.

Thus, altogether three are 45 species; six endemic, 19 indigenous and 20 exotic (including,naturalized species). Out of the s-ix endemic species five are in the wet zone. Abaremaabeywickramae, A. bigemina, Aca~ia lankaensis, Albizia lankaensis and A den anth era bicolor.One species, Painteria nitida is confined to the north central and eastern parts of the Dry zone.Out of the 19 indigenous species e.ght are Acacia species mainly in the arid and dry zones.There are four indigenous Albizia species occurring in all zones expect the arid zone. Two areNeptunia species both in the dry zone wetlands. The remaining five are Abarema subcoriaceaand Adanathera pavonina (mid country wet zone), Cathorimion umballatum and Dichrostachyscinera (dry zone) and Entada pusaetha in all zones except the arid zone. Of the twenty exoticspecies ten are Acasias growing in the hill country there is only one exoticA lbizia species and itclose in the mid and low country wet zone. There are Mimosa species one wide, one in the hillcountry and the third invasive (M. pigra). Of the remainning six, Desmanthus virgatus,Pithecellobium dulce and Vachellia farnesianar in the dry zone. Leucaena leucocephala occurswidely. Samanea saman is an avenue tree in dry and wet zones. Prosopis juliflora is invasive,although confined to the arid zone.