33G 



BOTANY: PRINCIPLES AND PROBLEMS 



among the ferns, and the sperms resemble those of bryophytes in 

 being bicihate. After fertiUzation the young sporophytc is 

 carried rather deeply into the prothallial tissue by a long cell, the 

 suspensor, and develops through its early stages largely at the 

 expense of the gametophyte. To this order belongs the large 

 genus Lycopodiutn, the familiar club moss or ground pine. 



Fig. 209. — Lycopodium. A, part of a plant of Lycopodium annotinum showing 

 prostrate stem and leafy, erect shoots bearing cones or strobili (s). B, sporophyll 

 or cone-scale, bearing a sporangium on its upper surface. C, one of the very 

 numerous spores produced in this sporangium, greatly enlarged. 



2. Selaginellales (Fig. 211). — This order is represented by the 

 genus Selaginella, which resembles Lycopodium rather closely in 

 vegetative structures but differs from that genus in being hetero- 

 sporous. Certain of the sporangia (the megasporangia. Fig. 

 211, B) produce four large megaspores each, and the others (the 

 microsporangia. Fig. 211, C) produce an abundance of much 

 smaller microspores. The history of the gametophytes is in 

 many ways like that described for the water ferns. The megas- 

 pore produces a small mass of cells, most of which are still retained 



