68 Mutations and Evolution 



The ordinary poison ivy, Rhus toxicodendron of North America, 

 has fruits glabrous or nearly so. A. H. Moore, 1 records from 

 Bristol, Maine, a form malacotrichocarpum with fruits abundantly 

 pilose. Oxalis stricta, var. viridiflora was described by Hus from 

 St. Louis, 2 differing from the type in having green petals. The 

 same form was afterwards found in plenty by Bartlett 3 near 

 Thomson, Georgia, doubtless arising from an independent mutation. 

 The petals are broader, apparently owing to a change in the shape 

 of the cells, and the presence of chloroplasts may perhaps represent 

 an independent change. Melica (Avena) stricta Michx. has glumes 

 strongly tinged with purple. Forma albicans Fernald, 4 the 

 prevailing form on some of the mountains of Maine and Eastern 

 Quebec, has glumes whitish or pale straw-coloured. Drosera 

 rotundifolia var. cowosa is a dwarf variety found by Fernald 5 in a 

 bog at the mouth of the Grand River, Gaspe Co., Quebec. It has 

 a sub-capitate inflorescence of few flowers, petals coloured, and the 

 ovary tending to develop into a rosette of grandular leaves. This 

 dwarf occupied a considerable area in abundance almost to the 

 exclusion of the normal. It is evidently a mutational form able to 

 survive in favourable conditions. 



Gaylussacia resinosa, the common huckleberry of America, has 

 black berries without a bloom. Var. glnucocarpa Robinson is 

 common in Eastern Connecticut 6 where it occurs in distinct clumps 

 generally associated with the species, from which it differs in 

 having blue glaucous fruits and also in its greater vigor and glaucous 

 leaves. Fernald (1917) describes a colony of Bidens by Lake 

 Pocotopaug, Connecticut, which differs from the species B. connata 

 of that region in having flat 2-awned achenes like B. heterodoxa of 

 Prince Edward Island. He interprets it as an outlying colony of 

 the northern species, but since its leaves resemble B. connata and 

 its var. petiolata it more probably represents a parallel mutation. 



The American saxifrage, Tiarella cordifolia L., extends from 

 New England to Minnesota and southwards. In Maine, New 

 Hampshire and Vermont two forms are found. 7 The plants differ 



Rhodora, 11 : 162. 1909. 



Rept. Mo. Bot. Garden, 18 : 99, 1907. 



Rhodora, 11 : 118, 1909. 



Rhodora, 7 : 244, 1905. 



Rhodora. 7 : 8, 1905. 



Sheldon, J. L., Rhodora, 4:14, 1902. 



Danforth, C, H., 1911. A dimorphism in Tiattlla cordifolig. Rhodora, 

 13: 192-3. 



