POLLEN MORPHOLOGY IN THE SELAGINEAE, MANULEAE (SCROPHULARIACEAE), AND SELECTED GLOBULARIACEAE, AND ITS TAXONOMIC SIGNIFICANCE

Abstract

The pollen grains of 22 genera and 182 species of Selagineae, Manuleae, and selected Globulariaceae were examined by light and scanning electron microscopy of whole and fractured pollen. Grains of the Selagineae and most Manuleae have trizonicolporate aperatures with long, unconstricted ectocolpi; clearly delimited margos; psilate colpus membranes; lalongate transverse endocolpi extending beyond the boundaries of the ectocolpi; thickened endoaperture margins; semitectate, reticulate to microreticulate exines; and psilate, simplicolumellate muri. In the Globulariaceae, Globularia has spinulose, microperforate exines and undifferentiated ectocolpus margins, and both Globularia and Poskea have granular to spinulose colpus membranes, lolongate endoapertures included within the ectocolpi, and unthickened endoaperture margins. These pollen data support postulated relationships between Selagineae and Manuleae, but pollen grains of Selagineae and Globulariaceae are distinct, and pollen morphology does not correlate with proposals combining these taxa in Globulariaceae or Selaginaceae. Pollen morphology in Glumicalyx is indistinguishable from that in most Manuleae and supports transfer of this genus to the Manuleae from the Digitaleae. Differences in pollen morphology supplement established morphological distinctions between Globularia and Poskea, but the pollen evidence does not support published infrageneric classifications in Globularia or postulated relationships between Selagineae and Gratioleae or Selagineae and Lagotis.