Contribution of ovule anatomy to the taxonomic context of Parodia Spegazzini (Cactaceae).

This article focuses on the taxonomic implications of ovule anatomy in the cactus genus Parodia Speg., which has a complex and debated circumscription involving the union of five previously separate genera into Notocactus sensu lato (s.l.) and later into Parodia sensu lato (s.l.). Through anatomical analysis of ovules from 15 species and two synonymous taxa, the study found that while ovules across Parodia s.l. share general features typical of Cactaceae (campylotropous, bitegmic, crassinucellate ovules with micropyles delimited by the inner integument), Parodia sensu stricto (s.s.) exhibits unique embryological traits such as nucellus and embryo sac projections and changes in micropyle type. These distinctive ovule characteristics support maintaining Parodia s.s. as a genus separate from the other genera synonymized under Parodia s.l., aligning with earlier taxonomic circumscriptions that separated Parodia s.s. from Notocactus s.l. The findings suggest that ovule anatomy provides valuable taxonomic characters for resolving infrageneric relationships and genus boundaries within this group of South American cacti.