Sorting and blending of unit characters. 223 



ing to the time in the season at which stem development begins. The 

 earlier in the season stem formation and branching- begins, the more 

 nearly normal will the habit be according to my observations. If stem 

 development is postponed nntil August or September the lower branches 

 diverge at a wider angle, and often grow for some distance nearly oj 

 quite parallel with the surface of the ground, the free end usually curved 

 more or less strongly upward. Many of these branches maj' be as long 

 or longer than the central axis, but the upward curving tip may not 

 reach the same height as the main stem. This peculiarity has been 

 observed in hyhrida pycnella, hybrida nutella and the cultures of pycno- 

 carpa referred to above where the seed was sown directly in the soil 

 of the garden in April, 1913; also in early flowering annuals grown 

 from seedlings transplanted to the garden in 1914. The wide spreading 

 habit of the lower branches has not been observed in nutans, no late 

 stem forming annuals of this species ha\äng appeared in 1913. In 1914 

 a few plants flowered as annuals and the basal branches were more 

 wide spreading than in the biennial forms. 



Among the 1913 cultures of pycnocarpa, where seeds were sown 

 in the green house during March, and the seedlings later transplanted 

 to the garden, only 2 out of 120 plants formed stems and flowers during 

 the first season. Stem development began late in the season, toward 

 the middle or last of August. In one plant the main stem was inclined 

 at an angle of about 45°, and tho, branches arising from the base of 

 the stem were wide spreading. In the other plant stem development 

 was somewhat later. The main stem only developed. This stem grew 

 parallel with the ground and was so rigid that it could not have been 

 brought to the erect position without breaking. As stated above, these 

 two annual forms started too late to mature seed, since there was a 

 severe frost September 10th. 



In another race of Oenothera from Ithaca, No. 17 of my cultures, 

 a large percentage of annual forms occurred in transplanted seedlings 

 in 1913. Some of these began stem development early enough to mature 

 seed. The branching of these forms was near the normal. But those 

 which began stem development from about the middle of August pre- 

 sented a wide departure from the normal, due to growth of the lower 

 branches nearly or quite parallel with the surface of the ground, and 

 at a tlistance from the main axis of 3 — 5 dm, and then curved upward. 

 In another species from Ithaca, Oenothera angustissima Gates (1913), 

 in my cultures of 1913, seedlings transplanted to the garden, a very 



