Classification of Plants 



169 



On the under side of most fern leaves you will find little 

 brown spots. Some people cut their ferns down and burn them 

 when they find these spots there, thinking that they are scale 

 bugs. When the spots get quite brown, gently shake a leaf 

 over white paper. A brown dust will appear on the paper. 

 These are the fern spores, contained within clusters of spore- 

 cases forming the dots. A dot is called a sorus (plural, sari). 

 When the spores are ripe and have fallen in moist places, they 

 burst their brow^n walls and begin to grow. In a few weeks a 

 spore will grow into a filmy, green, heart- 

 M W shaped plant. Look under the shelves of 



greenhouses or on the outside of pots in 

 which ferns are growing. The little hearts 

 are often abundant there. People call 

 them " Moss," but we know that moss 

 leaves are borne on stems. Each one of 

 these little hearts grows by itself. 



I. 



II. 



III. 



Fig. 174. — I. A moss plant (^Bryuj/i ar^cniejif//^. II. Capsule enlarged. III. Capsule 

 open for the spores to escape. (From Thome and Bennett's " Structural and Physio- 

 logical Botany.") 



How does the fern plant come ? On the under side 

 of the plants which are called prothallia are rhizoids and 

 two kinds of little pockets, resembling those in the liverwort 

 and the moss. The germ- or egg-cells are in the pockets near 

 the notch in the prothallium ; those containing the sperm-cells 

 are down near the point among the rhizoids. A sperm-cell 

 swims into the germ-pocket, unites with the germ-cell, and then 



