Minnesota Plant Life. 



•25 



If mosses proceeded no farther in their development than 

 tlie first-stage, tliey would be regarded as algae ; bnt there is 

 the capacity in all of them to develop brandies upon the first- 

 stage, arising from little buds of cells. The branch which thus 

 arises quickly takes the form of the mature moss or liverwort 

 and is known as the second-stage, or mature stage of the sexual 

 plant. Sometimes this mature stage is 

 itself a flattened body as in those broad, 

 forked, green plates which are found so 

 commonly on the damp sides of ravines. 

 More often the second-stage takes the 

 form of a stem upon which are borne 

 leaves. In liverworts 

 this stem is almost in- 

 variably quite pros- 

 trate, bearing two rows 

 of leaves, right and left, 

 and a third row of 

 scales on the under 

 side. Liverworts of 

 this sort are therefore 

 called, in common par- 

 lance, scale-mosses. 



In the moss division 

 of the general group 

 there are no forms in 

 which the second-stage 

 is a flat forking plate of 

 tissue, but \vithout ex- 

 ception the plant-body fig 

 consists of a leafy stem, 

 sometimes unbranched, 

 while in other varieties 

 it may be branched in 



a definite manner, often with some of the branches subordinated 

 to others, building up a fern-like or tree-like branch-system. 

 Very often this leaf-bearing branch-systern in mosses stands 

 more or less erect and then the leaves are generally arranged 

 around the stems in spirals quite as in higher plants. In one 



39. A male moss 

 plant. The sperm- 

 aries are produced in 

 clusters at the end of 

 the stem. After At- 

 kin.son. 



Fig. 40. A female moss plant. 

 The egg-organs are inclosed 

 in the tuft of leaves at the 

 tip of the stem. After At- 

 kinson. 



