224 



Many more comparative studies will be required before each step in 

 the process can be described in detail. All the conditions necessary for 

 the formation of a tamarack swamp can not now be stated, although two 

 are apparent (1) a relatively deep lake; (2) the destruction of this lake by 

 plant deposition, for this alone can produce the proper substratum for 

 the introduction of the tamarack. 



A list of the orders of plants and the species in each found in the 

 Leesburg Swamp: 



1. NYMPILEACE.E. 



Nuphar advena. 



2. Sarraceniace^e. 



Sarracenia purpurea. 



8. Geraniace^;. 



Impatiens b(fiora. 



4. Ilicine^e. 



Ilex monticola. 



5. Sapindace^. 



Acer rubrum. 



6. Anacardiace^;. 



Rhus venenata. 



7. Rosacea. 



Spirea salicifolia, S. tomentosa, Rosa Carolina, Polentilla Canailensis, P. 

 argentea, Rubus hispidus, Agrimonia. parviflora, Prunus Americana, 

 Pyrus coronaria. 



8. Crassulaceje. 



Penthorum sedoides. 



9. Droserace^. 



Drosera rotundifolia, D. intermedia. 



10. Onagrace.e. 



Epilobium striatum. 



11. CORNACEJE. 



Cornus Canadensis, C. florida, C. sericea, C. stoloni/era, C. paniculata, 

 Nyssa syleatica. 



