XVI International Botanical Congess

The Periplocoideae is distinguished from the Secamonoideae and Asclepiadoideae by the presence of free tetrads or pollinia which are shed on spoon-shaped translators after anthesis. The Secamonoideae is distinguished from the Asclepiadoideae by the four pollinia attached to a translator as against two pollinia in Asclepiadoideae. In the Periplocoideae the exine consists of a tectum and a granular stratum. In the Secamonoideae the exine consists of three layers, an outer tectum (which may be double layered), subtended by an electron light layer which is followed by a granular layer. In the Asclepiadoideae the exine consists of a tectum, a granular layer and an inner foot layer. Wall structure variation and structural changes inside the pollinia will be discussed.