THE BRYOPHYTES. 177 



In the sexual reproduction Mosses are either monoecious 

 or dioecious. Antherozoids swim to and fertilize the egg 

 cells produced in archegonia growing on the same or on 

 another plant. The result of this fertilization is the spo- 

 rophyte form of the plant, which develops in situ in the 

 archegonium. The capsules containing the egg cells be- 

 come filled with spores that closely resemble the asexual 

 spores of some other plants. The spore, in germinating, 

 produces a branching filament known as aprotonema, which 

 gives off lateral buds from which new Moss plants grow. 



POLYTRICHUM COMMUNE. 1 PRACTICAL STUDIES. 



Polytrichum commune, or Hairy-cap Moss, is one of the 

 largest and most common of the Mosses. It grows in 

 abundance in dark green patches in the woods, fields, and 

 along the road sides. The plants are from three to six 

 inches tall. The stems are usually simple, but sometimes 

 are forked. The leaves are from half to two thirds of an 

 inch long. (See Fig. 103.) 



1. With the naked eye examine some plants of Polytri- 

 chum commune. Find male or antheridial plants, recog- 

 nized by a starlike cluster at the top. (Fig. 103, M.^ 

 These clusters develop in the spring, but remain conspic- 

 uous throughout the season. Some male branches show 

 two or more clusters. After the formation of the lower 

 cluster, the apical bud continued to develop and formed 

 other clusters. This is known as prolification. Find an 

 instance of it. (See Fig. 103, P.) 



Find a female or archegonial branch. In the spring 

 the archegonium is concealed among the leaves of a stem 

 that is more pointed than the male stem. After fertiliza- 

 tion the female stem sends up a long, slender red shoot, or 



1 Similar Practical Studies might be made of any other Moss, as Sphag- 

 num, Mnium, Bryum, Atrichum, orBartramia. 

 CLARK'S BOT. 12 



