LYCOPSIDA 



51 



Protolepidodendrales 



Until 1953, when Aldanophyton was described from 

 Cambrian deposits in Eastern Siberia, ^^ Baragwanathia^^ 

 was believed to be the earhest representative of the Lycop- 

 sida, for it occurs along with Yarravia in Silurian rocks of 

 Australia. It had fleshy dichotomizing aerial axes, thickly 

 clothed with leaves, and must have had a most remarkable 

 appearance, for the diameter of the axes ranged upwards 

 from I cm to 6*5 cm (Fig. 8A). In the centre was a slender 

 fluted rod of annular tracheids from which leaf traces passed 



Fig. 8 



Baragwanathia : A, fertile shoot. Drepanophyciis : b, reconstruc- 

 tion; c, sporophyll. Protolepidodendron: d, reconstruction; 

 E, leaf scars on large axis ; F. sporophyll 



(a, after Lang and Cookson; b-f, Krausel and Weyland) 



