60 Mutations and Evolution. 



Philadelphia, having larger flowers than in the previous case. (6) 

 Meehan 1 records finding a double on the Wissanickon about 1854. 

 (7) One near Beverly Bridge, Mass., 1 with panicle smaller than 

 normal, the flowers full double, petals replacing both stamens and 

 pistil. (8) Meehan 3 reported a double from North Woburn, Mass. 

 These records, through trivial enough in themselves, acquire 

 interest when considered as a whole. For they show that in a 

 large part of its area and for over a quarter of a century 

 S. Virginiensis was producing sporadic doubles as mutations. It 

 is probably doing so still, and it may be that, as in stocks, some 

 individuals are eversporting, giving rise to fresh doubles in each 

 generation. 



Before leaving Saxifraga we may point out some of the other 

 derivative forms which have been described in this genus. Sterns* 

 describes a form of S. Virginiensis on Manhattan Island which he 

 called var. pentadecandra. In two plants observed nearly all the 

 flowers had 15 stamens, the extra 5 replacing the petals. In these 

 apetalous flowers the stamens were exposed in the bud. Such a 

 change of petals to stamens is relatively rare. Several other 

 plants in this location had apetalous flowers, but the stamens were 

 ill-formed and more or less aborted. Three more specimens were 

 found 8 in the locality in the following year. The same variation 

 occurs in the cultivated European species S.granulata, as recorded 

 by Masters. 



This must be regarded as a case of parallel mutations. In 

 5. crassifolia an abnormal increase in the number of pistils has 

 been repeatedly observed, while 5. Virginiensis var. chlorantha 

 Oakes was described from Topsfield, Mass., 1847, having tiny 

 green pubescent petals.' Var. pentadecandra was found in profusion 

 in a slate rock locality in Essex Co., Mass. The Saxifrages are 

 evidently subject in the wild condition to many mutations besides 

 doubling. 



Thalictrum anemonoides is another species for which there are 

 a number of records of doubling. A semi-double found near 

 Cincinnati, Ohio, in 1834 was taken into cultivation and in five years 



1 Amer. Nat. 2 : 484, 1869. 



1 Russell, J. L., Am. Nat. 3 : 327, 1869. 

 Amer. Nat. 6 : 487, 1872. 



* Sterns, E. E. Some anomalous forms of Saxifraga Virginiensis. Bull 

 Torrey Bot. Club 14 : 122125, 1887. 



1 Bull. Torrey Bot. Club 15; 166, 1888. 



See also Rhodora 19 : 143, 1917. 



