THE PTER1DOPHYTES. 203 



flammable. They have been extensively used, under the 

 name of lycopodium powder, to produce flash lights. 



There are about 100 species of the larger Club Mosses 

 in all the world, the greater number growing in the 

 tropics. About eleven species grow within the limits 

 of the United States, the most common ones with us 

 being Lycopodium dendroideum, or Ground Pine, L. clava- 



Fio. 131. Transverse section of stem of Lycopodium complanatum. E, E. 

 E, cortex; N, sclerenchyma; I, fibrovascular bundle sheath; S, phloem 

 portion; 0, xylem portion of the central fibrovascular bundle. (X 60.) 



turn, or Running Pine, and L. complanatum, sometimes 

 spoken of as Ground Fir or Ground Cedar. 



The plants of this order, while somewhat resembling 

 the Mosses in outward appearance, differ from them in the 

 character of their fructification and in their higher organi- 

 zation. The stems show centrally situated, well-defined 

 fibrovascular bundles which may be traced into the 



