2 86 MORPHOL OGY. 



buds which contain rudimentary shoot and root and several thick green leaves. 

 When they fall to the ground they grow into new lycopodium plants, just as 

 the bulbils of cystopteris do which were described in the chapter on ferns. 



583. Note. The prothallia of the species of lycopodium which have been 

 studied are singular objects. In L. cernuum a cylindrical body sunk in the 

 earth is formed, and from the upper surface there are green lobes. In L. 

 phlegmaria and some others slender branched, colorless bodies are formed 

 which according to Treub grow as a saphrophyte in decayed bark of trees. 

 Many of the prothallia examined have a fungus growing in their tissue which 

 is supposed to play some part in the nutrition of the prothallium. 



The little club mosses (selaginella). 



584. Closely related to the club mosses are the selaginellas. 

 These plants resemble closely the general habit of the club mosses, 

 but are generally smaller and the leaves more delicate. Some 

 species are grown in conservatories for ornament, the leaves of 



Fig. 328. Fig. 329. Fig. 330. Fifif.S.i.i. 



Selaginella with Fruiting spike Large spo- Small spo- 



three fruiting spikes, showing large and rangium. rangium. 



(Selaginella apus.) small sporangia. 



such usually having a beautiful metallic lustre. The leaves of some 

 are arranged as in lycopodium, but many species have the leaves 

 in four to six rows. Fig. 328 represents a part of a selaginella 

 plant (S. apus). The fruiting spike possesses similar leaves, but 

 they are shorter, and their arrangement gives to the spike a four- 

 sided appearance. 



