MUTANTS AND HYBRIDS OF THE OENOTHERAS. 53 



The hybrid O. lamarckiana X O. cruciata consisted of a single 

 type in which the characters of the pollen-parent were largely domi- 

 nant, although none of them were transmitted unchanged. A singu- 

 lar union of characters was shown in the relative lengths of the sta- 

 mens and pistils, a feature favoring cross and self fertilization. Some 

 of the flowers bore stamens shorter than the pistils, while in others 

 these organs were of equal length. Many of the modifications of the 

 predominating characters were dependent upon and were modified by 

 the alterations in the general stature of the plant. This hybrid corre- 

 sponds quite closely with the descriptions of 0. cruciata varza, a 

 supposed hybrid of 0. cruciata and 0. muricata given by De Vries. 



The hybrid of 0. lamarckiana X 0. biennis was of a pleiotypic 

 character, being composed of four well-differentiated types with no inter- 

 grading forms. This result differs widely from that obtained by De 

 Vries in hybrids with 0. biennis grandiilora and 0. muricata as the 

 pollen-parent. In both of the last-named instances the result of the 

 cross was a unitypic hybrid closely unilateral to the pollen-parent. 

 In 0. lamarckiana X 0. biennis some characters of both parents were 

 transmitted to all of the four types of the hybrid, but the greater num- 

 ber of the active characters were those of the pollen-parent. 



A remarkable predisposition or weakness to the attack of a 

 fungal parasite was exhibited by one of the types. The habit of ine- 

 quality of growth of the laminae resulting in crinkling, characteristic 

 of lamarckiana, was transmitted to all individuals of the four types of 

 the hybrid. The symmetrical form of the terminal rosettes of lamarck- 

 iana was transmitted unchanged to two of the types. No other char- 

 acters of the pistil-parent were inherited in their entirety, although a 

 number of qualities, approximating those of lamarckiana sufficiently to 

 be termed " dominant" by some authors, were seen. Three of the 

 types were goneoclinic to the pollen-parent, while the fourth (No. 2.24) 

 may be fairly taken as furnishing an example of an intermediate form, so 

 far as such estimations may be taken to be of value. The zigzag stem, 

 No. 2.27, is an example of the dominancy of a feature usually latent in 

 the pistil-parent, but exhibited by one of its mutants, rubrinervis. The 

 capacity for self-fertilization was dominant in three of the types, but 

 in the fourth a variability between cross and self fertilization was 

 indicated by the varying relative lengths of the stamens and pistils . It 

 is to be noted in this connection t'iat 0. brcvistylis, one of the mutants 

 of 0. lamarckiana Mas a pistil shoiierthan its stamens, and is therefore 

 adapted to self-fertilization, although no actual physiological predis- 

 position in the matter is found. 



