1919 ^^99^ ^^^ ^^9 Succession 209 



ment in the Puget Sound region to make any detailed statements on this 

 phase of the subject. It is, however, easy to distinguish in the field in 

 this region two groups of Sphagnum based on very obvious characters, 

 the distinction being readily confirmed by microscopic characters (Frye 

 1918). The first group contains the stouter more leafy ones (4< species 

 in all) which were so commonly used for surgical dressings during the 

 late war (Hotson 1918, Nichols 1918). The second group comprises 

 all other species of Sphagnum found in the region, some 20 in number. 

 They are characterized by being more slender in appearance and having 

 much fewer leafy branches. The mosses taking part in the bog develop- 

 ment on the Carlisle prairie, except in rare instances, all belong to the 

 first group. Those in the Maltby bog, the Mud lake bogs, the Sunnydale 

 bog, and the ones growing near Fairfax and along the north fork of the 

 Skykomish river all belong to the second group. The bogs at Poulsbo and 

 Kitsap lake comprise both groups, frequently growing side by side. 



Summary 



1. Numerous instances of early stages of bog succession are to be seen 

 in the Puget Sound region. 



2. Sphagnum often grows in drained places and thus does not form bogs 

 unless drainage is obstructed. Examples are seen at Fairfax and on 

 the north fork of the Skykomish river. 



3. Hummocks of Sphagnum grow on poorly drained prairie and thus 

 form bogs. Examples of this are seen around Carlisle. 



4. An instance is seen at Covington in which Sphagnum is abundant in 

 an undrained depression but no bog is formed. Probably time is the 

 element lacking. 



5. Sphagnum advances upon swamps, growing among or upon sedges 

 and rushes, and the bog thus succeeds the swamp. Illustrations of 

 this are found in Fauntleroy bog, Maltby bog and Poulsbo bog. 



6. Bogs gradually fill lakes, the Sphagnum advancing by the support 

 of woody bog plants. Instances of this are seen at Crystal lake 

 and Mud lake. 



7. Bogs also fill lakes by the aid of herbaceous plants which are not 

 characteristic of later bog stages. Instances are seen at Sunnydale 

 and Mud lake. 



8. Sphagnum often advances directly into shallow water without the aid 

 of other plants. Examples are seen in Henry bog, the IMud lake 

 bogs, at Yakutat in Alaska, and on the Carlisle prairie. 



