Pollen exine morphology has been widely surveyed in the phlox family with considerable discussion regarding its taxonomic utility. However, with the exception of thorough SEM sampling of Collomia, work in Cobaea, and description of general classes of mucilage production and cell-separation characteristics, seed coat micromorphology has been largely neglected in Polemoniaceae. A broad SEM survey of mature, dry seeds throughout this family reveals diversity in characteristics of cell wall boundaries, presence, absence, size, shape, and distribution of verrucae, and features of the hilum. Similar to the general uniformity in seed coats reported for Collomia, the seeds of Gilia sensu sticto show little variation: verrucae are either absent or minutely developed in the earliest branching species. Segregate genera Lathrocasis and Saltugilia, also members of Gilieae, are characterized by substantially larger verrucae and cell wall boundaries obscurely apparent as low ridges, but differ in finer levels of verrucae appearance. Two markedly different patterns distinguish the testa of former Gilia species removed to Linanthus, with both types represented in other members of Phlocideae. In Loeselieae, Aliciella, Giliastrum, Bryantiella, and Dayia possess distinctive testa and three readily distinguishable patterns are found in Aliciella alone. Although the several classes of external morphology noted in this study correspond well to lineages of Polemoniaceae identified in DNA-based phylogenetic analyses of this family, the greater value of this work is the description of characters for morphology-based phylogenetics and further investigation into seed evolution in this family.

Key words: Gilia, phylogeny, Polemoniaceae, seed morphology, systematics