182 BOTANICAL GAZETTE [MARCH 
O. salicastrum and O. salicifolia.* The first plants are as high as 
O. biennis Chicago, attaining 2 and sometimes (1914) almost 3 
meters in height. They differ mainly in having narrower leaves. 
The salicifolia, on the contrary, is different from its parent species 
in almost all respects, being richly branched and rarely attaining 
one meter in height. It has almost linear leaves of a special blotted 
green, small erect flowers and long thin fruits. Analogous muta- 
tions have from time to time been observed in hybrid cultures of 
O. biennis Chicago. 
Under the name of metaclinous hybrids I have described the 
curious phenomenon that heterogamous species from time to time 
produce among their hybrids from one cross, in one or a very few 
specimens, the type which is ordinarily that of the reciprocal 
hybrid.” For instance, the cross O. biennis ChicagoXO. Lamarck- 
tana gives the twin hybrids densa and laxa, while O. Lamarckiana 
XO. biennis Chicago produces the twins O. laeta and O. velutina. 
Now among the first hybrid cultures sometimes a velutina, and 
more rarely a Jaeta, arises, and among the latter sometimes a /axa. 
Evidently some latent mutation, on the part of O. biennis Chicago, 
must be responsible for the production of these aberrant types. 
Analogous metaclinous hybrids have been described for O. atro- 
virens Bartl.*° 
Narrow-leaved mutations have also been seen in cultures of 
O. muricata, and of late (1914) in those of O. suaveolens Dest.* 
Moreover, O. grandiflora, collected by Mr. Barttetr and myself 
at Castleberry in Alabama, throws off aberrant forms, one of which 
has broader and the other almost linear leaves. 
8 For descriptions and figures see Gruppenweise Artbildung. pp. 304-307- 
9 Op. cit. p. 308. 
3% This is the et described in my book esi sacii Artbildung under the name 
of O. cruciata. For its metaclinous hybrids see pp. 310 
3 For the Mite varieties and mutations ay O. muricata see also GATES, R. R., 
A contribution to the knowledge of the mutating Oenotheras. Trans. Linn. Soc. II. 
Bot. 8:1-66. pls. 1-6. 1912. 
# For O. grandiflora see GATES, op. cit. p. 38. If the three types of O. grondifors, 
observed in my garden, occur also at Dixie Landing, Alabama, and have crossed, 
of them, with O. Tracyi, and have perhaps produced twin hybrids and unlike recip- 
rocals, this might explain the large number of forms observed on that spot; see Science 
38:600. 1912. 
