Membership in Societies
- Fellow of the Linnean Society (London) (FLS)
- Member of the International Organization of Plant Biosystematists
- Member of the International Association for Plant Taxonomy
- Member of the American Society of Plant Taxonomists
- Member of the Botanical Society of America
- Member of the Systematics Association
- Member of the International Organization for Plant Information
- Member of the Organization for the Phyto-Taxonomic Investigation of the Mediterranean Area
- Member of the Czech Botanical Society
- Member of the Slovak Botanical Society