Phylogenetics and taxonomy of liverworts and hornworts

The bryophytes (mosses, liverworts and hornworts) are the second largest group of land plants after the flowering plants, with around 20,000 species worldwide.

Ecologically they are important in water conservation, as protectors of soil in preventing soil erosion, as nitrogen and carbon sinks. They are particularly important as biological soil crusts in semi-arid and arid woodlands and grasslands, conserving the top layer of soil in those environments.

We are studying the taxonomy and evolution of Australian hornworts and liverworts to understand the diversity of bryophytes which are found in Australia.

Currently, our team is concentrating on the complex thalloid liverwort family Ricciaceae. The family consists of two genera, the monotypic, semi-aquatic and cosmopolitan Ricciocarpos natans and the biodiverse Riccia. We are presently revising Riccia for Australia, including sequencing all species, identifying and describing new species, and undergoing fieldwork in areas that have been under-collected for the genus.

In the last few years we have published a preliminary phylogeny of Australian Riccia and also a taxonomic revision of species found in the northern monsoon tropics of the Northern Territory.

We are also revising the hornworts of Australia. The anthocerotes are a very small group, with around 200-215 species worldwide. They are distinctive amongst the bryophytes in having such unique characters as a horn-like capsule which produces spores continuously, a symbiotic relationship with cyanobacteria, and typically a single large chloroplast per cell with a special carbon-concentrating organelle associated with it, known as a pyrenoid. While most diversity occurs in the tropics, recent discoveries of new species have been in the dry country of north western New South Wales.

Other groups of interest include the simple thalloid liverwort genus Fossombronia and the complex thalloid liverwort genus Asterella. Both are very common in southern Australia as soil crust components.