Produced by the Population Genetics and Evolution class, Furman University

The Silurian: Baragwanathia
Originally discovered in Australia and dating from the late Silurian period, Baragwanathia is one of the earliest known vascular land plants (Lang and Cookson 1935). This extinct genus is considered a member of the lycopsids, or club mosses, occuring before the emergence of members of the modern genus Lycopodium (Kaslev 2002). There is some controversy surrounding its temporal placement due to its greater complexity than the vascular plants found in the northern hemisphere, but this has been mostly resolved by grouping with animal organisms from the period, such as graptolites (Kaslev 2002). Baragwanathia longifolia, one of the better-known species, was composed of long, thick stems covered in slender leaves. Sporangia may have grown either along the stems of leaf bases, although this is uncertain. Though a mere 1-2mm in radius, these stems could reach up to a meter in length (Dimech 2009). This species represents an important period of transition from water-dependent algae to tracheophytes, the vascular plants adapted to life on land. It has similar branching properties to some species of green algae, and is postulated to have descended from them. More of the fossil record, though, will be required to confirm this (Dimech 2009).

Page by Will Towler
Baragwanathia longifolia. Photo by Yvonne Arremo at Naturhistoriska riksmuseet .

Kaslev M. 1999. Drepanophycales. www.palaeos.com. Accessed Feb. 7, 2010.

Lang W, Cookson I. 1935. On a flora, including vascular land plants, associated with Monograptus, in rocks of Silurian age, from Victoria, Australia.” Philosophical Transactions of the Royal Society of London. 224: 421-449.

Dimech A.2009. Adam Dimech’s Plant Evolution. Accessed Feb 18, 2010.