94 A Study of the Vegetation of 



viduals of Pseudotsuga and Abies, confined generally to the 

 canyons and rich levels at the bases of north slopes. 



These mountain slopes were overrun by fire on August 21 and 

 22, 1910. As they seemed to represent fairly the average forest 

 conditions for northern Idaho, it was decided that here would be 

 a most satisfactory place to carry on a study of the problem of 

 natural reforestation. 



Among the first pioneers to reclaim the unshaded and charred 

 soil were Funaria hygromWrica and Marchantia polymorpha. 

 Cirsium palousense, Erigeron acris, and Epilobium angustifoUum 

 were the chief herbs, whose wind-blown fruits afforded them an 

 early entrance. Likewise, the numerous seedlings of Sdix 

 scouleriana may be accounted for in the same manner, while 

 numerous others sprang up from the underground parts of the 

 older willows characteristic of more open areas. The presence of 

 Opulaster pauciflorus, Arnica cordifolia, and Erythronium grandi- 

 florum may likewise be accounted for by the fact that the fire 

 left unharmed the rootstocks of the shrub and of Arnica and the 

 corms of the lily. 



In the spring of 1911 and the second year after the fire, Epi- 

 lobium angustifoUum was predominant everywhere. The indi- 

 viduals varied from mere seedlings to plants 12-18 inches in 

 height, often as many as 30 to 50 individuals occurring in a single 

 square meter. Thousands of the smallest were succumbing to an 

 epidemic of Aecidium. Next in importance to the fireweed was 

 the thistle, Circium palousense, which with Antennaria lusuloides 

 and the species enumerated as occurring the preceding year, 

 formed a considerable herbaceous carpet over the burned area. 

 Every inch of the ground otherwise unoccupied seemed covered 

 with Funaria hygrometrica. The following shrubs, Opulaster 

 pauciflorus, Rosa gymnocarpa, and Rubus parviflorus, which were 

 more or less abundant, had, like several of the herbs in the fol- 

 lowing list, been able to survive the fire by means of underground 

 propagative parts. The bulbs of ZygadenusvenenosusandFritil- 

 laria lanceolata, and the corms of Erythronium grandiflorum, all 

 of which were present in considerable abundance, were found at 

 depths of 5-7 inches below the surface of the soil. Other plants 



94 



