SPERMATOPHYTES : GYMNOSPERMS 345 



arising from the fact that what were supposed to be sexual 

 organs in Phanerogams have proved not to be such. The 

 name Phanerogam, therefore, is being generally abandoned ; 

 but the name Cryptogam is a useful one when the lower 

 groups are to be referred to ; and the Pteridophytes are 

 still very frequently called the Vascular Cryptogams. The 

 most distinguishing mark of the group seems to be the 

 production of seeds, and hence the name Spermatopliytes, 

 or "Seed-plants," is coming into general use. 



The seed can be better defined after its development 

 has been described, but it results from the fact that in this 

 group the single megaspore is never discharged from its 

 megasporangium, but germinates just where it is devel- 

 oped. The great fact connected with the group, therefore, 

 is the retention of the megaspore, which results in a seed. 

 The full meaning of this will appear later. 



There are two very independent lines of Seed-plants, 

 the Gymnosperms and the Angiosperms. The first name 

 means "naked seeds," referring to the fact that the seeds 

 are always exposed ; the second means " inclosed seeds," 

 as the seeds are inclosed in a seed vessel. 



Gymnosperms 



225. General characters. — The most familiar Gymnosperms 

 in temperate regions are the pines, spruces, hemlocks, 

 cedars, etc., the group so commonly called "evergreens." 

 It is an ancient tree group, for its representatives were 

 associated with the giant club-mosses and horsetails in 

 the forest vegetation of the Coal-measures. Only about 

 four hundred species exist to-day as a remnant of its for- 

 mer display, although the pines still form extensive forests. 

 The group is so diversified in its structure that all forms 

 can not be included in a single description. The common 

 pine (Pinus), therefore, will be taken as a type, to show 

 the general Gymnosperm character. 



