VEGETATION OF FLATHEAD LAKE 357 



trees, there are several others; yellow pine, lowland fir, birches, 

 cottonwood, hawthorne, maple, alder, and juniper. The islands 

 are covered with the same kind of forest. 



In some places the forest reaches to the very edge of the rock 

 cliffs which rise abruptly from the water of the lake; between 

 the rocky points, some of the bays are rilled with extensive swamp 

 meadows. East of Poison at the south end of the lake is a large 

 swamp. At the head of the lake the delta of the Flathead River 

 extends for a long distance and here there are sandy beaches. 

 The swamps merge into meadows, and are backed by swamp 

 thickets of alder, dogwood, birch and willows. With these ex- 

 ceptions the stony beach is practically continuous around Flat- 

 head Lake and around the islands. 



The successions of shore vegetation may be classed as follows: 



Xerophytic. A, The rock shore succession; B, the stony beach 

 succession. 



Hydrophytic. A, The swamp meadow succession; B, the 

 delta swamp succession. 



All these successions result finally in the climax forest and the 

 transitional stages can be traced. 



A. The rock shore succession 



The first plants to appear upon the rocks are the lichens. 

 The crevice plants are next to appear, followed by mosses and 

 ferns. If the rocks are at a steep angle and exposed to wind and 

 waves the development is very slow. One of the most interesting 

 of crevice plants is a little blue violet seen in the cracks of the 

 bare rocks at Idlewilde and some of the other islands. It also 

 grows among the stones on the beach. The Jacob's ladder is a 

 conspicuous rock plant and with it grows a small hairy mustard, 

 Arabis hirsuta, and the brittle fern, Cystopteris fragilis. When a 

 certain amount of soil has been formed the kinnikinnick takes 

 possession and forms a solid heath mat. This is followed by 

 various woody shrubs; roses, gooseberries, currants, ninebark, 

 and buffalo berry. As the forest plants increase tree growth 

 begins. 



