ON VARIETIES IN PLANTS 



303 



Origin of Sweet Pea Varieties. The sweet pea, Lathyrus odoratus, 

 provides an excellent illustration of the origin of varieties by the utili- 

 zation of mutations. Its history as a horticultural plant is known from 

 the beginning and has been thoroughly reviewed in publications of the 

 Cornell Station. The sweet pea was introduced into Holland and 

 England from Sicily via Italy in 1699, and was first illustrated in a 

 description published in 1700. The drawing is reproduced in Fig. 120. 

 It will be noted that in habit it was similar to the cultivated sweet peas 

 of the present day and the height to which it would climb was "6 or 



FIG. 120. Commelin's drawing of the sweet pea in Hort-Medici Amstelodamensis, 1700. 



(After Seal,) 



7 feet," but the flower stems were short and bore only two flowers, while 

 the flowers themselves were relatively small, with erect or reflexed 

 standard and conspicuous, depressed wings. In color the standard 

 was reddish purple and the wings light bluish purple. From this modest 

 beginning there have been developed several distinct types of plant and 

 flower forms and a list of named varieties, even within the most highly 

 developed type of flower (the Spencer or waved form), which includes 

 over 500 entirely distinct colors, tints, shades, and combinations. 

 By far the greatest amount of this work has been accomplished during 

 the past 50 years, during which period hybridization has been used 



