THE EVENING PRIMROSES OF DIXIE LANDING, ALABAMA. 553 



found of which the broad leaves were somewhat crinkled, but so 

 slightly so as to suggest that the variation was merely individual 

 or accidental. 



The classification of the types of Oe. Tracy i takes no account of 

 the width of the leaves, or of the degree and kind of pubescence. 

 Of course a more complete analysis of the composition of the Oeno- 

 thera population at Dixie Landing will be made when the rosettes 

 have flowered in Washington and a second generation has been 

 grown from self-pollinated seed of all the forms found in the col- 

 lection. At the present time it is sufficient to point out that no 

 Oenothera from Dixie Landing, however constant it may seem to 

 be when grown generation after generation from self-pollinated 

 seed, can be cleared of the suspicion that it may be of hybrid origin. 

 In other words, the same suspicion that attaches to so many of the 

 strains of Oenothera Lanmrckiana in Europe attaches to any strain 

 of Oenothera grandiflora which is now being used by experimenters. 



It is therefore of some importance to compare the conditions 

 under which Oe. grandiflora grows at Dixie Landing with the condi- 

 tions under which Oe. Lamarckiana occurs at its European stations. 

 The race of Oe. Lamarckiana which occurs at Hilversum is un- 

 mixed, since no other species of Oenothera grows at that locality. 

 Of its mutants only Oe. laevifolia and Oe. brevistylis have been ob- 

 served to flower regularly in the field: the other forms either do 

 not flower at all or only so rarely as to have hardly any influence 

 on the purity of the strain. In the sand dunes of Holland, on the 

 contrary, Oe. Lamarckiana is mixed, as a rule, with European Oe. 

 biennis and is observed to produce the three different hybrids which 

 are obtained when these two species are artificially hybridized. The 

 same statement holds good for many localities where the two species 

 grow in France and England. Every individual from such a station, 

 however closely its external characters may seem to coincide with 

 those of one of the parent species, must always lie open to the sus- 

 picion of having had a hybrid ancestry. 



In connection with the fact that the Dixie Landing types are so 

 sharply divisible into two groups, it is permissible to suggest that 

 they may correspond in a general way with hybrids between Oe. La- 

 marckiana and Oe. biennis "Chicago" which have already been 

 studied. From the cross Oe. Lamarckiana x Oe. biennis "Chicago" 

 and its reciprocal, two pairs of twin hybrids were obtained at Amster- 

 dam in the first generation, viz., Oe. laeta and Oe. velutina, and 

 Oe. densa and Oe. laxa. The first pair of twins, from the cross Oe. 



