Embryology and circumscription of Campanulaceae and Campanulales: A review of literature

Abstract

Embryological studies of Campanulaceae and related families were reviewed to add to discussion of appropriate circumscription of Campanulaceae and Campanulales. Embryological features are very uniform within Campanulaceaesens. lat. (Campanuloideae and Lobelioideae), and provide no evidence for the separation of Lobelioideae as a distinct family. Campanulaceaesens. lat. share with several other families traditionally included in Campanulales (or Asterales) a few derived embryological features (i.e., unitegmic and tenuinucellate ovules, an endothelium,ab initio Cellular type endosperm, and an endosperm haustorium). However, an extensive comparison with families in an expanded Asteridae shows that those derived embryological features are symplesiomorphies, rather than synapomorphies indicative of close relationships among them. Combined with other morphological (inferior ovary), chemical (presence of inulin), and molecular (rbcL gene nucleotide sequence) characters, embryological features rather support a broad circumscription of Campanulales (or Asterales) including Pentaphragmataceae, Stylidiaceae, Campanulaceaesens. lat., Donatiaceae, Menyanthaceae, Calyceraceae, Goodeniaceae, and Asteraceae. Within Campanulalessens. lat. (or Asteralessens. lat.), Menyanthaceae, Calyceraceae, Goodeniaceae, and Asteraceae are obviously closely related to one another. To understand more exact relatonships within the order, embryological studies are needed onBrunonia, Cyphia, Cyphocarpus, Nemacladus, Corokia, Abrophyllum, Argophyllaceae, and Alseousmiaceae.