PTERIDOPHYTES 



131 



Figs. 288-293. — Embryo (sporophyte) of Lyco- 

 podiwm clavatum: 288, first division of egg into sus- 

 pensor cell and embryonal cell; 289, 290, division of 

 embryonal cell into four cells (290 being a cross sec- 

 tion); 291-293, further stages in the development of 

 the embryo. — -After Bruchmann. 



Fig. 294. — Young 

 sporophyte of Lycopo- 

 diwm clavatum^ show- 

 ing foot, primary root, 

 and stem bearing 

 scale leaves. — After 

 Bruchmann. 



embryo sporophyte, found in certain pteridophytes, as the Lycopo- 

 diales, but very characteristic of seed plants 



Phylloglossum 



This is an Australasian genus of one species, closely allied to Lycv- 

 podittm and thought by some to be the most primitive pteridophyte. 

 The sporophyte body is a tuberous stem bearing a cluster of small 

 leaves. Some of the sporophytes also develop a short, naked stalk 

 bearing a terminal stobilus (fig. 295). Some species of Lyco podium 

 begin with this type of body, but the strobilus-bearing stalk becomes 

 branching and leafy, and the tuberous embryonic body disappears. 

 The adult body of Phylloglossum, therefore, is like the embryonic body 

 of some species of Lycopodium. In other species of Lycopodium this 

 kind of embryonic body is absent from the life history. The gameto- 

 phyte resembles that of Lycopodium, in which there is a subterranean 



