Systematics and Evolution (HA)
Bryophytes
Liverworts and Hornworts studies
Young sporophytes of hornwort Phaoeceros |
Project Leader: Christine Cargill
(CSIRO: lw69)
This is a brief introduction for those who are perhaps unfamiliar with bryophytes. The mosses, liverworts and hornworts were traditionally lumped together under the division Bryophyta, as a consequence of these plants sharing very similar habit and life cycles. In general they are small herbaceous plants with an alternating life cycle consisting of a dominant, persistent vegetative gametophyte, and a short-lived sporophyte which is nutritionally dependent upon the gametophyte. More recently they have come to be recognised as three distinct divisions or phyla, arising from three distinct ancestors. They are now known as the Bryophyta (mosses) the Marchantiophyta (liverworts) and the Anthocerotophyta (hornworts). The liverworts are in turn divided into three morphologically and developmentally distinct groups. These are the leafy liverworts, which as the name suggests possess a simple stem and two or three rows of leaves; the complex thalloids, whereby the thallus is differentiated into distinct layers with airpores on the upper surface; and the simple thalloids which can appear either like the leafy liverworts or like the complex liverworts.
My research interests lie with the liverworts and hornworts, and one of the aims of my work is to bring into axenic culture as many of the liverworts and hornworts that I will be working on, for molecular and experimental work.
My previous research involved a partial revision of the simple thalloid liverwort suborder Fossombroniineae, revising the genus Fossombronia and Sewardiella for Australia, Africa, Southwest Asia (the Middle East) and the subcontinent of India. Future projects will look into the taxonomy, phylogeny and phylogeography of the genus Fossombronia as well as the suborder.
Within the genus Fossombronia I am wanting to establish whether differences occur at the molecular level between those populations which are currently conspecific but which occur worldwide as well as in Australia. Much of the diversity of the suborder is still unknown within Australia, and in particular in Western Australia, South Australia and New South Wales. Two other genera within the suborder; Austrofossombronia and Petalophyllum are also understudied for Australia and these genera will also be included in my studies.
Asterella is a complex thalloid liverwort, which is a widespread species, both within Australia and worldwide. A recent revision of this genus for the Northern Hemisphere by David Long has revealed that the Australian species are not as clear cut in their delineation as thought but may involve a complex. Molecular and morphological parameters would be used.
In terms of the hornworts, genera are still not clearly defined and the interrelationships between each of the genera are also somewhat unclear. I am involved in a collaborative project using both morphology, molecular and biogeographic work to clearly define the genera and to determine the phylogeny within the group itself.
|
