Plant Science Portal 
Victorian Baragwanathia Flora
 Plant Evolution Tour: Part V of XV

Baragwanathia fossils were first discovered in Yea, Victoria in 1875, and were first described by Australia's eminent pioneer botanist, Dr. Isobel Cookson in 1935.

Baragwanathia is a lycopod which was derived from the Zosterophylls. It showed a remarkable degree of specialisation; the process of the development of structures for a particular purpose. It is because of this degree of specialisation that there is dispute over the age of the Yea fossils.

Many palaeobotanists believe that the fossils date from the late Silurian - approximately 420 Ma or early Devonian (410 Ma). If it dates from the early Devonian, then despite its complexity it was present on the land before all other plants with the exception of Cooksonia.
Detail of Baragwanthia longifolia.
Detail of Baragwanthia longifolia. [Image reproduced from Willis & McElwain 2002]
Baragwanathia longifolia had long thick stems which were 1-2 millimetres in radius and which were densely covered with long slender leaves to 4cm in length. The stems could be as long as 1 metre in length. Sporangia grew either along the stems or on the leaf bases (there is some uncertainty about this).

By any measure, it is clear that by 400 Ma, vascular land plants had evolved from the water-dependant algae. What isn't clear is whether there was a single precursor land plant, and the evolutionary path that was followed between the algae and vascular land plants. It is thought that the vascular land plants probably developed from the Green Algae (Chlorophyta). One extant species which is often cited is Fritschiella of the Charophyaceae.
The alga Fritschiella
The alga Fritschiella.
But it was not only the vascular plants (tracheophytes) which colonised the land. Non-vascular plants (bryophytes) also colonised land at this time, however because of their morphology were less amenable to fossilisation and hence the fossil record is incomplete for this group of plants.

Another uncertainty is whether the vascular plants and non-vascular plants had a common ancestor, or whether the vascular plants evolved from the non-vascular plants. Current thinking is that the Charophyaceae contains a common ancestor for tracheophytes and bryophytes.

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