278 



The Plant World. 



The Alnus-Myrica association, which follows, is here domi- 

 nated by Myrica carolinensis and Kalmia augustifolia. But 

 Alnus incana is abundant. Viburnum cassinoides, Ledum gioen- 

 landicum, Ilex verticillata, Pyrus arbutifolia, and P. sitchensis 

 are frequent, The undergrowth is mainly Aspidium thelypteris, 

 Osmunda cinnamomea, Equisetum pratense, Dicksonia punctil- 

 lobula, Symplocarpus foetidus, and Lonicera canadensis. On 

 drier sphagnum hummocks Chiogenes hispidula and Cornus 

 canadensis are prominent, with Oxalis Acetosella, Rubus hispid- 

 us, Aspidium spinulosum intermedium, and Smilacina trifolia 

 as frequent associates. 



Xear the railroad station at Tusket is an extensive bog which 

 presents a shrub stage not found in the two bogs mentioned 

 above, although seen elsewhere; the Chamaedaphne-Rhodora 

 association. The ground cover is of sphagnum overgrown with 

 Rubus hispidus. Chamaedaphne calyculata, Rhodora canadensis, 

 Ledum groenlandicum, Kalmia augustifolia, Andromeda glau- 

 cophylla, Spiraea salicifolia, and Chiogenes hispidula foim the 

 bulk of the vegetation. Small tamaracks and black spruce are 

 scattered throughout. The accessory species indicate a tendency 

 toward the development of the Alnus-Myrica association, but in 

 this bog the Chamaedaphne-Rhodora association passes directly 

 into the forest formation. The list includes Gaylussacia baccata, 

 Vaccinium oxycoccus, V. macrocarpon, Scirpus cyperinus, 

 Eriophorum gracile, E. virginiana, Sarracenia purpurea, Drosera 

 rotundifolia, Amelanchier canadensis, Alnus incana, Myrica 

 Gale, M. carolinensis, Ilex verticillata, and Xemopanthes mu- 

 cronata. 



Farther to the east the bog has passed over to the tree stage, 

 exhibiting a dense growth of Picea mariana and Larix laricina 

 (the Picea-Larix Formation). There are occasional trees of 

 Abies balsamea and Picea canadensis. The undergrowth is 

 principally the yew (Taxus canadensis), Hypnum Schreberi, and 

 Sphagnum. In the interioi this undergrowth is sparse, but 

 toward the better lighted margins occur many plants alieady 

 listed under the preceding association. 



The transition to the Picea Formation is very gradual as 

 shown at several nearby points. The tamarack occurs as a 

 straggler in the spruce forest even on the higher elevations. 



