INVESTIGATION ON OCCURRENCE AND ULTRASTRUCTURE OF THE PROTEINACEOUS NUCLEAR INCLUSIONS (PNIS) IN THE BIGNONIACEAE, WITH SPECIAL REFERENCE TO THE GEOGRAPHIC-DISTRIBUTION PATTERNS

This paper analyzes the occurrence and distribution of Proteinaceous N uclear Inclusions (PNIs) in the family Bignoniaceae. In 52 out of 70 e xamined species (corresponding to 74.2%) nuclear inclusions with lamel lar substructure are observed. An additional crystalline body, derived by packing of lamellar inclusion subunits during cell development, is reported in several taxa. PNIs are recorded in all studied tribes, bu t with different distribution. Most Tecomeae and all taxa of Crescenti eae, Coleeae, Oroxyleae, Eccremocarpeae and Schlegeliae show PNIs. In most Bignonieae they are lacking. The occurrence of PNIs in two tribes considered to be the oldest groups of Bignoniaceae and related to the ancestral stock of Tubiflorae, Tecomeae and Oroxyleae, support their presence as an ancestral trait. Although systematic conclusions in Big noniaceae cannot to be made in consequence of the great structural hom ogeneity of PNIs, the relationships between occurrence data and geogra phic distribution patterns, are discussed. Finally, the placement of S chlegelia and Paulownia, regarded as transitional genera between Bigno niaceae and Scrophulariaceae, are analyzed.