CH. XV] LEPIDODENDRON 93 



Lepidodeudron. 



i. General. 



The genus Lepidodendron included species comparable 

 in size with existing forest trees. A tapered trunk rose vertically 

 to a height of 100 feet or upwards from a dichotomously 

 branched subterranean axis of which the spreading branches, 

 clothed with numerous rootlets, grew in a horizontal direction 

 probably in a swampy soil or possibly under water. A 

 description by Mr Rodway^ of Lycopods on the border of a 

 savannah in Guiana forming a miniature forest of Pine-like 

 Lycopodiums might, with the omission of the qualifying 

 adjective, be applied with equal force to a grove of Lepidodendra. 

 The equal dichotomy of many of the branches gave to the tree a 

 habit in striking contrast to that of our modem forest trees, but, 

 on the other hand, in close agreement with that of such recent 

 species of Lycopodium as L. cernuum (fig. 123), L. obscurum 

 (fig. 124) and other types. Linear or oval cones terminated 

 some of the more slender branches (fig. 188) agreeing in size and 

 form with the cones of the Spruce Fir and other conifers or with 

 the male flowers of species of Araucaria, e.g. A. imbricata. 

 Needle-like leaves, varying considerably in length in different 

 species, covered the surface of young shoots in crowded spirals 

 and their decurrent bases or leaf-cushions formed an encasing 

 cylinder continuous with the outer cortex. The fact that leaves 

 are usually found attached only to branches of comparatively 

 small diameter would seem to show that Lepidodendron, though 

 an evergreen, did not retain its foliage even for so long a period 

 as do some recent conifers. 



By the activity of a zone of growing tissue encircling the 

 cylinder of wood the main trunk and branches grew in thickness 

 year by year : the general uniformity in size of the secondary 

 conducting elements affords no indication of changing seasons. 

 As the branches grew stouter and shed their leaves the surface of 

 the bark resembled in some degree that of a Spruce Fir and other 

 species of Picea, in which the leaf-scars form the upper limit of 



I Rodway (95) A. p. 153. 



