70 Mutations and Evolution. 



Pernald 1 describes Silene antirrhina, L. forma Deaneana as 

 differing from the type only in the absence of the glutinous band 

 found on some of the internodes in the type. This form is 

 occasional throughout the range of the species, and is constant in 

 the colonies where it occurs. A considerable number of mutations 

 in wild species are given by Hus (1911), and a number of others 

 have been discussed by the writer 2 in their relation to phylogeny. 

 Betula nana, L. var. Michauxii, of Newfoundland and adjacent 

 portions of Canada,' differs from the type chiefly in that the bracts 

 of the pistillate aments are commonly simple and oblong instead of 

 3-lobed. Similarly B. alba, L. var. elobata, Fernald, which occurs 

 on Mt. Albert in Gaspe" Co., Quebec, differs from the type in the 

 same respect and is evidently a parallel mutation. Near New 

 Boston, New Hampshire, a tree of B. lenta was found having 

 deeply serrate leaves, 4 a unit variation. Laciniation of leaves and 

 petals is one of the commonly recorded types of variations in plants. 



Rhaninus caroliniana, Walt, is glabrous or glabrate. The var. 

 nwllis, Fernald* differs in having its leaves densely velvety beneath. 

 The pubescent variety occurs in different parts of the range of the 

 species. There is no evidence as to which is the older type. In 

 Erigeron ramosus the reverse change has apparently taken place. 

 Var. septentrionalis. Fern, and Wieg. 6 differs in having greener 

 foliage, the leaves being sparsely hispidulous or nearly glabrous, 

 instead of cinereous-strigose. The glabrous variety is more 

 northern than the species, occurring in Newfoundland, Eastern 

 Canada, New England and Idaho. This may be because it is better 

 adapted to a cold climate, or merely because it happened to arise 

 in a more northern latitude, but the former seems more probable. 

 A number of species have northern glabrous varieties, but in other 

 species a pubescent variety of a glabrous species is more northern 

 in its distribution. A somewhat different case is found in Fragaria 

 Virginiana, var. terra-novce," 1 which differs from the type in having 

 the pubescence of the petioles and leaves closely appressed. The 

 variety is abundant in Newfoundland, Southern Labrador, and 

 the Gaspe Peninsula where the type is a rarity. It occurs as far 



1 Rhodora, 17 : 96, 1915. Also 12 : 129, 1910. 



1 Gates (I917c). 



Fernald, M. L., Khodoi-a, 16: 168, 1913. 



4 Sanford, S. N. P., Rhodora, 4, 83, 1902. 



Rhodora, 12:79, 1910. 



Rhodora, 15 : 59, 1913. 



Fernald and Wiegand. Rhodora, IS : 106, 1911. 



