46 



DE. E. E. GATES— CONTEIBUTION TO A 



E2 a uniform race numbering 23 plants. They varied in height from one to two feet, 

 but otherwise agreed in having O. grandiflora flowers and general leaf characters. 

 This dwarf race of 0. grandiflora is clearly different from O. nanella. Still another 

 dwarf race had the following history. It arose in another race (No. 49) which closely 

 resembled No. 40, the plant yielding in Pi 80 offspring which were fairly uniform, 

 except one rosette which resembled an overgrown O. gigas, and 2 dwarfs. The next 

 generation from one of the latter yielded a uniform progeny of 20 plants. Unlike 

 the last dwarf races, they averaged only one foot high, and their leaves resembled 

 O. nanella, but they had O. grandiflora flowers and buds. It is evident^ then, that 

 constitutional dwarf races may easily occur in these forms. 



Numerous other types are now being grown in E2 and will be described in detail 

 later. My cultures of these forms furnisli abundant evidence that rather uniform 

 true-breeding races can be obtained from this evidently hybrid progeny. Indeed, my 

 experience has been that most of these races of hybrid ancestry will breed reasonably 

 true, at least, after the Pi, though, as might be expected, there is usually more variability 

 in these races than in the mutants of DeVries which have been inbred for a number of 

 generations. 



In all cases of which I am aware, of crosses between large-flowered and small-flowered 

 Oenotheras (see Section on hybridization, p. 52), the flowers of the Pi hybrids are 

 intermediate, both as regards size of petal and length of style. As showing that an 

 analysis of a mixture of races such as I am describing is possible, I may refer to one 

 race (070.4) derived from a single individual in my sowings of 1908. The first generation 

 of offspring from this plant numbered 60 uniform individuals, and four of these, self- 

 pollinated, yielded in all over 200 for the second generation. They constituted a very 

 uniform race, and a careful comparison showed that their characters were identical in 

 every respect with those of the hybrid 0. nanella X O. biennis, which also breeds true 

 {cf. Section on hybridization where the rosettes are described). The stem-leaves of this 

 race (070.4) were found to be rather exceptionally variable, varying from pointed at 

 both ends and petiolate, to sessile with broad base, uncrinkled. The dimensions of 

 the flowers were as follows: — length of ovary 8 mm., hypanthium 32 mm., cone 



29 mm., sepal tips 5 8 mm., diameter of cone at base 5-7 mm. There is considerable 

 variability in the length of style, the stigma being above the anthers in some, but 

 touched by their tops in others, though it is apparently never so long as in 

 O. Lamarchiana or so short as in 0. biennis. This race much resembles 0. riibrinervis 

 in general appearance, on account of its usually red midribs in the rosette-leaves. But 

 the buds are shorter and more slender (base of cone 9 mm. in diameter), the rosette- 

 leaves are usually less crinkled, and the two forms cannot really be confused, the 

 smaller flowers, of course, making the race distinct. 



The numerous other races I am now cultivating from this source will be described in 

 detail elsewhere. Abundant confirmation is, however, already furnished for the 

 interesting fact that in Oenothera hybrid races with characters intermediate between 

 their parents frequently breed true. The q[uestion of the gametic composition of such 

 races, and the reasons why they breed true, will be referred to in the next section. 



