Pollen morphology and ultrastructure of the Old World Antirrhineae (Scrophulariaceae)

Abstract

The morphology of mature pollen grains of all Old World genera in the [Matter is not Clear Here] (Scrophulariaceae) is described with light, scanning and transmission electron [Matter is not Clear Here] The results showed a considerable morphology uniformity. Grains from 82 [Matter is not Clear Here] belonging to 74 taxa were 3-colporatc, typically isopolar, radially symmetrical, [Matter is not Clear Here] polar axis from 12.2 to 30.5 urn and mean equatorial diameter from 11.1 to 21.6 urn, shape spheroidal to prolate. Colpi fusiform or narrowly oblong, colpus membrane smooth or granular. Three morphological categories are recognized based on colpus shape and colpus membrane together with three subtypes based on grain shape. Linaria spartea is remarkable with perforate tectum and striate-reticulate exine. A mosaic pattern of evolution in Old World Antirrhineae pollen is supported. Comparative analysis based on the available data of pollen morphology from other tribes and from closely related families suggests that 3-colporate pollen grains, with microreticulate exine, fusiform colpi, smooth colpus membrane and more or less spheroidal shape appear to be the most primitive pollen type in the family Scrophulariaceae.