MONOHYBRID SEGREGATION IN 

 MALVA SPECIES 



BY KAHL n. KJUSTüFFEIiSON 



INSTITUTE OF GENETICS, ÂKARP, SWEDEN 



THE old opinion that species hybrids })reed true to type is now 

 abandoned. (3n the contrary, most species hybrids have been 

 found to show a very compHcated segregation in Fo — I do not con- 

 sider here the cases, where the constancy may be due to compHcations 

 in the reduction division in Fi (Federley 1913). The de Vriesian 

 idea of the existence of special species characters, which would be 

 constant in the F2-generations of species hybri(^s, whereas the varietal 

 characters would segregate, has also proved incorrect. Most crosses 

 between different varieties of a species show a rather simple segrega- 

 tion in F2. However, the different behaviour of the Fa-generations 

 does not give any clue as to the nature of the hybrid, whether it is 

 a cross between different species or between varieties of one and the 

 same species. On the contrary, very complicated segregations have 

 been found to result when different varieties have been crossed. Some 

 species hybrids, on the other hand, show a rather uncomplicated Fa- 

 segregation. The hybrid Pisum arvense X sativum may be mentioned 

 as an example. The same has been found to be the case with the 

 hybrid here recorded, viz. Malva oxyloba, Boiss. X parviflora, L. 



Both these species resemble each other much. According to 

 BoissiEH (1867) Flora Orientalis the differences lie mainly in the dif- 

 ferent development of the lobes of the leaves and the sepals. The 

 leaves of M. parviflora (fig. 1:2) are circular-cordate with 5 — 7 rather 

 small lobes; the leaf-margin is serrulated. The lobes of the sepals 

 (fig. 1: 1) are rounded and pointed. At the ripening of the fruits 

 the sepals increase considerably in size. M. oxylaba has about the 

 same leaf shape but the lobes of the leaves are divided into lanceolate 

 lobules with serrated margin (fig. 1: 1). The lobes of the sepals 

 (fig. 1: 1) are ovate triangular. The size of the sepals do not increase 

 in such a high degree when the fruits are ripening as is the case with 

 M. parviflora. In examining my material I have not been able to find 

 any additional differences between these species. 



