THE PTERIDOSPERMS AND THE SEED 251 



refer to are among the most important ever made in 

 plant morphology. 



In Lecture VIII. I mentioned the name of Binney, a 

 Lancashire lawyer, who had been attracted to the study 

 of fossil trees in the St. Helens Coalfields, as the discoverer 

 (in 1866) of a petrified stem which received the name 

 of Lyginodendron Oldhamium. This stem was described 

 by WilUamson a few years later, and in greater detail 

 by WilUamson and Scott in 1895, when it was shown to 

 possess anatomical characters which connected it with 

 the Cycadaceae, with hints, in the young shoot, of the 

 Osmundaceae. The first step in placing this remarkable 

 plant in its proper category was the recognition of the 

 fact that its foUage was that of a " fern " long known 

 as Sphenopteris Honinghausi, while the superficial pro- 

 minences on both stem and leaves led to the identification 

 of the " fern " petiole, known as Rachiopteris aspera, 

 as the leaf-stalk of Sphenopteris, and hence of Lygino- 

 dendron. The plant was thus seen to combine both 

 Cycadaceous and fern-like vegetative characters, and to 

 such synthetic forms Potonie, in 1897, apphed the group 

 name CycadofiHces. 



Some of these epidermal outgrowths were discovered 

 to be of the nature of stalked glands, and glandular 

 structures of the same character were shown by Oliver 

 and Scott, in 1903, to be developed on the investing 

 cupule of a seed which WiUiamson had found and named 

 Lagenostoma Lomaxi. OHver and Scott, from the occur- 

 rence of these unique -glands, as also from a detailed 

 investigation of the anatomy of the vascular system of 

 the peduncle, had no difficulty in proving that the seed 

 Lagenostoma was the fructification of Lyginodendron. 

 As the seed is now described and figured in every botanical 

 textbook I need not do more than say that it presents 

 all the fundamental features of a Cycad seed, pollen 

 chamber, central nucellus column and all. Here, then, 

 was a fossil tree with pronounced secondary thickening. 



