ON VARIETIES IN PLANTS 309 



a previous chapter. Semi-dwarf, early-flowering sports have appeared 

 even more frequently than those of the Cupid type. They have been 

 made the basis of the winter-flowering types of sweet peas. Ordinary 

 sweet peas pass into a semi-dormant condition for a time after germination, 

 growing very slowly until sideshoots have been developed. The winter- 

 flowering sorts, however, promptly send up a central axis which begins 

 blossoming as soon as it has attained a height of from two to four feet. 

 The Blanche Ferry group of varieties apparently had their inception 

 in a mutation of this sort which a woman in northern New York noticed 

 among some plants of the Old Painted Lady. She selected them for 

 about twenty-five years after which they passed into the hands of a 

 seedsman. From this stock a series of early flowering mutations have 

 arisen in the order shown below. Black-seeded varieties are indicated 

 by (6) and white-seeded ones by (10). 



Old Painted Lady (6) 



I 

 Bright-flowered sport (6) 



I 

 (30 years later) Blanche Ferry (6) 



Extra Early Blanche Ferry (6) Emily Henderson (white, w) 



I I 



Earliest of all (6) Mont Blanc (early white, w) 



I I 



Extreme Early Earliest of all (6) Earliest Sunbeams (primrose, w ) 



I 

 Earliest White (6) 



FIG. 125. New varieties of sweet peas which originated by mutation among the progeny 



of Old Painted Lady. 



Hybridization and Selection in Sweet Peas. The era of extensive 

 hybridization in sweet peas dates from about the year 1880, consequently 

 we can say but little of definiteness after that time with respect to the 

 origin of new factors in the sweet pea save in a few particularly favorable 

 cases. Laxton's Invincible Carmine was the earliest recorded new variety 

 which was produced by crossing, and its parents are reputed to have been 

 Invincible Scarlet and Invincible Black. We can easily understand, 

 therefore, how it originated, for it is apparently merely an improved form 

 of Invincible Scarlet resulting from the inclusion of the factor for intense 

 pigmentation of Invincible Black in the factor complex of Invincible Scar- 

 let. Similarly by hybridization it has been found possible to establish 

 families of varieties such as the Spencer, the hooded, the grandiflora, 

 and the winter-flowering sorts. Hybridization has throughout been 

 merely a means of fully utilizing germinal differences which have arisen 

 by mutation. It is true that in most cases we cannot say just when the 



