Katharina Urmi-König’s research while affiliated with University of Zurich and other places

A taxonomic revision of the genus Elodea (Hydrocharitaceae) is presented with full descriptions of each species with diagnoses, synonyms with typifications, distribution maps and illustrations also containing information on ecology, floral biology, anatomy, morphology, chromosomes, genetics, physiology and applied aspects, with an extensive bibliography. Five species of Elodea are recognised and one (E. granatensis Humboldt and Bonpland) is replaced in the genus Apalanthe. All species are from the New World, but some have become widely naturalized in the Old World. New morphological, ecological, distributional, genetic and cytological information is incorporated.

A taxonomic revision of Ottelia (Hydrocharitaceae) in Eurasia, Australasia and America is presented with a key, full descriptions, synonyms with typifications, diagnoses, distribution maps and illustrations, also including information on ecology, floral biology, chromosomes, genetics, variation and applied aspects. Within the chosen area eight species and one variety are accepted. Several previously recognized species are reduced to synonyms, and no taxonomic novelties are described.

A taxonomic revision of the genus Egeria (Hydrocharitaceae) is presented with full description, diagnoses, synonyms with typifications distribution maps and illustrations, also containing information on ecology, floral biology, anatomy, morphology, chromosomes, genetics, physiology and applied aspects, with an extensive bibliography. Egeria is considered to contain two species, each native in South America, but one (E. densa Planchon) has become widely naturalized in other parts of the world. New morphological, ecological, distributional, genetical and cytological information is incorporated.

A taxonomic revision of the genus Limnobium (Hydrocharitaceae) is presented with full descriptions, diagnoses, synonyms with typifications, distribution maps and illustrations and including information on ecology, floral biology, anatomy, morphology, chromosomes and variation with a rather extensive bibliography. Two well-defined and allopatric species are recognized: L. spongia (Bosc) Steudel, eastern North America and L. laevigatum (Humboldt & Bonpland ex Willd.) Heine, Central and South America. The genus Hydromystria is not considered to be worthy of recognition and is included within Limnobium. New chromosome counts are reported.

A taxonomic revision of the genus Stratiotes (Hydrocharitaceae) is presented with a full description, diagnosis, synonyms, distribution maps, illustrations including information on 15 fossil species, ecology, floral biology, anatomy, embryology, variation and applied aspects with an extensive bibliography. Stratiotes is considered to be, at the present time, monotypic; the single living species (S. aloides L.) maintains itself mostly through vegetative growth and sets viable seed in a relatively small area within the total geographical range. Fossil seeds are often abundant and extend back to the Middle Eocene (ca. 48 million years ago) and are found more or less within the geographical range of S. aloides today. The seeds show a progressional anagenesis and show an increase in length of about 1 mm every 7 million years. The regulation of the annual floating and sinking of Stratiotes is controlled by the activity of young leaves in spring and their death and consequent waterlogging in autumn.