Pollen morphology of Lagotis (Scrophulariaceae)

Abstract

The pollen grains of 18 species of Lagotis have been examined using light microscopy and scanning electron microscopy of whole and fractured pollen. The grains are characterized by tricolporate apertures with smooth to sparsely granular ectocolpus membranes; lolongate endoapertures with unthickened margins included within the ectocolpi; relatively large exinous processes over the endoaperture; and columellate, semitectate, reticulate to microreticulate exines with or without supramurial processes. Lumina are reduced in size toward the colpus, but the transition is gradual, and a sharply bounded, differentially sculptured colpus border is absent. Lagotis pollen is distinct from that of the Selagineae and Globularia and indistinct from that of some Veroniceae; however, the characters shared with the latter are of wide occurrence in the Scrophulariaceae. Pollen morphology supports the distinction between L. brachystachya and L. stolonifera. It is consistent with the postulated close relationship between L. micrantha and L. integra, and provides no evidence to support the reestablishment of L. cashmeriana, L. minor, L. pallasii, or L. kunawurensis as species distinct from L. glauca. Key words: pollen morphology, Lagotis, Globularia, Selagineae, Veroniceae.