THE PTERIDOPHYTA 



215 



neither the Hepatics nor Mosses may be considered as worthy of note in 

 commercial pharmacognosy. In the Mosses, the top of the stem or 

 branch bears a number of bracts or modified leaves, which constitute 

 the Perichaetium. From amidst these bracts the Pedicel (Fig. 596, s) 

 rises from the foot and bears the capsule upon its summit. Through 



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Fig. 597 The male organ, antheridium of 

 mosses (Funaria): A, antheridium, with escaping 

 antherozoids (a); B, a single male element b, in 

 mother cell; C, free, with two cilia. 



^^i^sj?^-;^;^^-^, 





Fig. 598. Lycopodium: S, the cone-like spore- 

 bearing leaves; B, an enlarged sporophyll leaf; 

 b, the blade, and sp, the sporangium which con- 

 tains the spores. 



the center of the capsule the Pedicel is continued as the Columella, and 

 at its summit it is closed in until mature by one or more coverings. By 

 a special organ, the Peristome, consisting of a number of teeth, it is 

 possible for the capsule to be closed during wet weather and opened 

 for the distribution of its spores when it is dry. 



The Pteridophyta. — All three groups of this division contribute more 

 or less important articles to the commercial materia medica. 



Equisetaceae. — In this group again we have, as in the flowering 

 plant, a gametophyte which is microscopic, although, unlike that of 

 the flowering plants, it is produced entirely disconnected from the 

 sporophyte. From it develop hollow-stemmed plants which are com- 

 monly known as horse-tails or scouring rushes. The latter name is in 

 allusion to the large amount of silica produced in their superficial 



