Part of our large collection of plants at the Australian National Herbarium is dedicated to a group of organisms called cryptogams. This group consists of algae, fungi, slime moulds, lichens, liverworts, mosses and hornworts. The one feature these all have in common is that they reproduce by spores. They do not produce flowers or seeds.
Within this group, the mosses, liverworts and hornworts are collectively called bryophytes. Bryophytes are non-vascular plants which means they do not have internal conducting systems for transporting nutrients and water. They can vary in size from tiny, just over a millimetre tall to those that grow as hanging strands ending up well over a metre in length.
Lichens are in a group of their own. They are a symbiosis between two organisms. They form a mutualistic association between a fungus and a green alga or a cyanobacterium, which simply means the two partners live together closely and happily.
Very useful tiny organisms
In Australia there are approximately 2,000 species of bryophytes, made up of about 1,200 species of mosses, 900 liverworts and 20 hornworts. Of the 20 000 lichens known worldwide, Australia is home to over 3800 of them.
In semi-arid and arid regions, cryptogams are often the predominant vegetation cover, in the form of biological soil crusts. In these habitats, they are important for water retention and nutrient recycling and help prevent soil erosion.Bryophytes and lichens can live in almost all parts of the terrestrial world, from Antarctica to arid Australia. They are found, from sea-level to alpine habitats, and even occur in suburban backyards and on man-made substrates such as brick or concrete walls or paths.
Bryophytes are interesting from an evolutionary point of view, being considered the amphibians of the plant world for the ancient characteristics that link them both to their algal ancestors and to terrestrial plants.
Yet there is still much mystery surrounding the evolution of these important organisms.
Our researchers are using the collection at the Australian National Herbarium to better understand the taxonomy, evolutionary relationships, biogeography and ecology of bryophytes.
This work has built a better picture of the species of the liverwort genus Riccia which make up biological soil crusts in the monsoon tropics of northern Australia compared to those that occur in southern Australia. Or how a tiny salt-tolerant liverwort, Monocarpus sphaerocarpus growing around salt lakes and marshes has managed to spread right across southern Australia. Could it be by spores carried by wind or on the feathers or feet of wading birds?
As scientific techniques have evolved, so too has our ability to study the secrets of symbiosis, expanding our understanding of nature’s unique abilities. Our researchers are looking to characterise the interactions between the organisms in lichens, particularly in lichens that form soil crusts.
Understanding the development of lichens will provide insights into their resilience in the face of changing environments.
And in a new field of exploration called synthetic biology, understanding the interaction of symbiotic organisms could lead to the production of lichens in controlled environments, and to the engineering of symbiotic organisms for other applications such as production of valuable natural products.
Our collections are a vast source of new and as yet untapped genetic potential that we are just beginning to explore.
Interested in tiny things? We’ve teamed up to take a look at microbes in the environment.