Deceptive taxonomic importance of the Ornithogalum (Asparagaceae) seed morphology

Ornithogalum taxonomy is under constant revision. Numerous studies relating to morphology, anatomy, cytology, seed micromorphology and molecular phylogenies have been published to date, yet the number of species within the genus continues to be debated. In the Mediterranean region and rest of Europe, the genus comprises c. 120 species that share many common characters. In published resources, seed morphology has mostly been designated as species specific, having low taxonomic value for higher systematics. However, our comparative review of the published data and additional comparative analyses of seed morphology, detailed here, has revealed some discrepancies and limitations in species identifications. Our study included 14 Ornithogalum species, sampled from the Balkan Peninsula and Pannonian Plain. The main aims of the study were to describe seed structure characteristics, determine features upon which species could be identified, and examine the taxonomic relevance of differentiating characteristics. We confirm considerable variability in seed dimensions and shape. Testa primary structure exhibits non-species-specific features and we identify secondary testa structure as being an additional parameter for seed description. Overall, we found that while it is possible to define particular seed morphology patterns, they are of limited value in the taxonomy of this genus.