MUTATIONS OF OENOTHERA SUAVEOLENS DESF. 245 



flower in September only, too late for successful artificial fertilization. 

 The mutations, observed in 1914, 1915 and 1916, belonged to the 

 following types (Opera VII, p. 42): 



(a) Taxonomic changes: Oe. suaveolens mut. apetala. 



(b) Parallel mutations: Oe. suaveolens mut. lata, mut. sulfurea and 

 mut. lutescens. The parallelism is mainly with Oe. Lamarckiana in 

 the first case (fig. 1), with Oe. biennis in the second, and in the third 

 with Oe. grandiflora. 



(c) Narrow-leaved types: Oe. mut. fastigiata and Oe. mut. jacu- 

 latrix (figs 2 and 3). 



Other narrow-leaved types have been grown from seeds of different 

 origin and will be mentioned later on. Narrow-leaved mutations 

 are common in Oe. Lamarckiana and have been observed in some 

 other species. Analogous changes constitute, as is well known, a 

 main difficulty in the cultures of Oe. Lamarckiana mut. gigas. 



These new mutations differ from the parent species by one or two 

 striking marks, and show, besides these, some secondary characters, 

 exactly as in the case of the derivatives of Oe. Lamarckiana and 

 other species. Their main characteristics are: 



(1) Oe. suaveolens mut. apetala. Flowers without petals, leaves 

 narrow, stature low. But this is a half-race, producing also flowers 

 with one or more petals. 



(2) Oe. suaveolens mut. lata. Stature, flowers and fruits of Oe. 

 Lamarckiana mut. lata, but smaller. Some flowers with a small 

 supply of pollen, others without fertile pollen grains. An incon- 

 stant race, splitting into lata and typical suaveolens (fig. 1). Number 

 of chromosomes 15. 



(3) Oe. suaveolens mut. sulfurea. Flowers sulfur. 



(4) Oe. suaveolens mut. lutescens. Foliage pale, especially in spring- 

 time. 



(5) Oe. suaveolens mut. fastigiata. Side branches and flowers 

 erect; foliage narrow in youth (fig. 2). 



(6) Oe. suaveolens mut. jaculatrix. Foliage very narrow throughout 

 the whole life of the plants (fig. 3). 



The four last-named types are constant and uniform from seed, 

 excepting their mutability, which is essentially the same as that 

 of the parent species. To this latter, however, they do not 

 return. 



I will now describe these mutants separately and give their 

 origin, their offspring and the results of some crosses made with 

 them. 



