XVI International Botanical Congess

Nearly 50% of the species grows in SAmerica and are recognized in 31 sect. of 2 subgenera.Cluster analysis and ordination are used to study phenetic relationships among the SAmerican sections.Total sections are examined and 26 morphological characters are used.The results point out the unclear phenetic distinction at subgeneric level.The dendrogram shows the differentiation of sections into groups.The outstanding groups comprises:Margarethia,Monadelpha,Disciferae (filaments fusion columnar),Sphaerantha,Spinosa,Chondrocarpa (subshrubs with vigorous shoots),Lasiogyne, Macrogynodium (exhuberant vines).The principal component analysis shows the valuable characters to determine sectional limits.Previous proposals for the reduction of the number of sections are discussed and a formal synonymy is presented.