ipiSl BARTLETT— MUTATION IN OENOTHERA 95 



linear-lanceolate. The stems were simple. No. 7 died just 

 before flowering, when only 7 cm. high. No. 12 flowered at a 

 height of 10 cm. The ovary was 7 mm. long; hypanthium 10 mm. 

 long; calyx segments 4 mm. long, excluding the distant free tips, 

 which were i mm. long. The calyx differed from that of the typical 

 form not only in having distant calyx tips, but also in being densely 

 soft-pubescent. Unfortunately, this plant was sterile and pro- 

 duced no seeds. As far as the writer is aware, mut. pusilla repre- 

 sents the extreme of nanism in the subgenus Onagra. 



With a single exception, the 7 suspected dwarfs developed as 

 quite normal plants, indistinguishable from the mass of the culture. 

 One plant, no. 19, differed from the rest in that it had stiff, distant 

 calyx tips 5 mm. long which were continued on the angles of the 

 squarish bud as a marked carina. The buds were ahnost glabrous, 

 as in the type form of the culture, but in marked contrast to some 

 of the other mutations. This plant was self-sterile, but produced 

 abundant seeds when pollinated with typical 0. pratincola. 



The Lexington C culture which was grown to maturity in 

 1913 included, besides the 9 plants from the first sowing and the 

 mutations and suspected mutations of the second sowing, all the 

 plants from two pans in which there appeared to be no variation. 

 There were 72 of these plants, nos. 23-94.'* When they matured 

 two mutations were found which had not been detected in the 

 early seedling stages. With these two exceptions, the plants were 

 absolutely uniform among themselves, and exactly the same as 

 Lexington A, Lexington B, and Lexington E. (Of each of these 

 three strains 30 plants were grown to maturity.) The two muta- 

 tions were not alike and were different from any of the other new 

 types which had been obtained. .Both, however, were almost 



18 The culture numbers of these plants are all given here in order to avoid lengthy 

 repetition in subsequent papers which will deal with the same strains. It may be 

 well to explain that every plant in the writer's garden is designated by the name of 

 the strain (for which a number has often been substituted) followed by a succession 

 of numbers which indicate the pedigree and number in the culture of each individual. 

 Subscripts are used when it is wished to distinguish between sister plants grown in 

 different years, or to indicate the years in which the successive generations were 

 grown. "Lexington C-1113," for example, would be the complete designation of the 

 plant of mut. niimmularia which is shown in fig. 6. Plants of the Fa generation, grown 

 in 1914, would be "Lexington C-1I13-I14," "Lexington C-11-2," etc. 



