Differential Polyploidy Within the Blackberries

A LL European Rubi Eubati can be divided into two large groups: rtEubati veri and Rubi Corylifolii.Eubati veri (as well as Rubi Corylifolii) consist of a series of species and microspecies with different taxonomic value.From a practical point of view they may be placed.in six taxonomical groups.The first group comprises the very few main-species, which are sexual and diploid and have a southern area of distribution, namely R. tomentosus and ultnilolius.Both are plainly distinguished from other Rubi Eubati.The first-mentioned species forms a uniform and seemingly depauperated group of biotypes, while R. ulmifolius consists of a large number of forms closely related to each other.In spite of this polymorphy R. ulmifolius is a characteristic and isolated species.In the same group of species FOCKE [(1878 and) 1914] also placed R. caucasicus and incanescens, which so far have not been examined cytologically or genetically.Even R. ccesius -distributed throughout Europe and mostly rather common -is placed by him in this group.LIDFORSS (1914 and earlier) showed, however, that Scandinavian members of this species are obligate apomicts, and GUSTAFSSON (1933 a. and unpublished; cf. also LONGLEY, 1924 and ROSANOVA, 1934) determined that several representatives have the tetraploid chromosome number.Within the remaining Eubati veri there is a great variation due to hybridization.In fact, the different groups (subsectlos ) consist of a large number of transitional forms.Great many localized and endemic microspecies have arisen.Except a few species with a large area of distribution, the different regions display clusters of forms -often vegetatively propagated in a luxuriant manner -which it has been impossible to group together with the non-endemic species occurring in the region.But as has been shown by LIDFORSS, even several so-called good species are heterozygous to a surprisingly great extent.Crosses between them or even segregation products may therefore give origin to floras of blackberries, so rich in biotypes that each limited area con-Hereditas XXl'.3