SOME SEGREGATES OF OENOTHERA. 133 



with rather conspicuous red midribs; stem leaves also fre- 

 quently with red michibs, otherwise very similar to those of 

 0. Lamarckiana, not always whitish. Petioles of rosette leaves 

 margined for some distance. Sepals usually with conspicuous 

 red stripes varying in width. Hypanthium green. Stem 

 generally less stout than in 0. Lamarckiana, usually with more 

 side branches and sometimes slightly zigzag. 



Oenothera rubricalyx. 



This conspicuous form first originated in my cultures as 

 a mutant from 0. rubrinervis two years ago. The same 

 identical type has since appeared as one of two types in the 

 Fi of 0. nanella pollinated from a certain strain of 0. bien- 

 nis. In both cases it breeds true except for certain indi- 

 viduals which revert to 0. rubrinervis, the percentage of 

 reversions being a simple Mendelian ratio in the last case, 

 and possibly also in the first. A full description of this form 

 will appear elsewhere in connection with an account of 

 Oenothera cultures. 



0. rubricalyx is clearly distinct from 0. rubrinervis and 

 there are no intermediate forms. The only distinguishing 

 feature of this mutant is its greatly increased production of 

 red pigment (anthocyan). It is differentiated from 0. rubri- 

 nervis in having much pigment on the under surface of the 

 rosette leaf petioles, and on the hypanthium as well as the 

 whole of the sepal, including the median longitudinal ridge. 

 This latter makes the buds very conspicuous so that they 

 are distinguishable from 0. rubrinervis at a glance. There 

 is also an increase in pigment production on the stem and 

 in other parts of the plant. 



Oenothera lata DeVries. 



See vinder 0. Lamarckiana. Die Mutationstheorie. 1 : 169. /. 4^, buds; 

 1 : 220. /. 58, leaf; 1 : 288. /. 88, flowering shoot; 1 : 289. /. 89y 

 rosette leaf, bract and terminal rosette; 1 : 294. /. 91, rosette; 1 : 295. 

 /. 9S, rosette; 1 : 321. /. 101, fruits; 2 : 240. pi. 1, colored; 2 : 496. 

 pi. 3, colored. 



Rosette leaves very broad, oblong, with very obtuse tips, 

 lighter green and very much crinkled. Stems often weak 

 and more or less decumbent. Buds greenish, rounded and 



