The tribe Abildgaardieae Lye is composed of 5-7 genera: Crosslandia, Fimbristylis, Abildgaardia (= Fimbristylis section Abildgaardia), Bulbostylis, Nemum, Nelmesia and Tylocarya (= Fimbristylis nelmesii). There has been little disagreement about the general boundaries of the tribe. However, limits of the main genera are disputed and unresolved. Some species and generic boundaries of Crosslandia, Abildgaardia and Australian Bulbostylis require assessment across their morphological and geographical range of distribution. The general aim of this thesis is to test monophyly of and within the tribe Abildgaardieae. To address the aim, the limits for Crosslandia, Abildgaardia and Australian Bulbostylis are assessed to determine the species and generic limits on a global level. Data from morphology, vegetative anatomy and embryo morphology were used in phenetic and cladistic analyses. Phenetic analyses of morphological data were used to test and set species limits. Additional characters from morphology, vegetative anatomy and embryo morphology were used in cladistic analyses to test monophyly of the tribe and previous classifications. Representative samples from Fimbristylis, Nemurn, and the monotypic genera Nelmesia and Tylocarya (= Fimbristylis nelmesii) were added to those species defined in phenetic analyses. Data were polarised using the outgroup method; with outgroup taxa selected from the provisional Arthrostylideae, Schoenoplectus and Schoenoplectiella. Cladistic analysis revealed that the tribe Abildgaardieae is not monophyletic when Nemum, Nelmesia and Tylocarya are included. Members of 'Arthrostylideae' violated monophyly of Abildgaardieae. The limits of Crosslandia and Abildgaardia are revised: Crosslandia 4 spp., all endemic to Australia and Abildgaardia 11 spp., 9 in Australia, 8 endemic. The limits for Australian species of Bulbostylis remain unresolved, with further testing of a wider sample of overseas species needed. A new species of Bulbostylis, B. kakadu ined., is recognised. Species of Nemum are not monophyletic and Nelmesia rendered Abildgaardia non-monophyletic in the full tribal analysis. Tylocarya fonned a clade with Fimbristylis depauperata. Species of Fimbristylis did not fonn a monophyletic group. Suggestions for further work are given.