Chromosomes and reproductive behaviour of Finnish Taraxacum agamospecies

Abstract

Hyrkas-Lyytikainen, K. 1984. Chromosomes and reproductive behaviour of Finnish Taraxacurn agamospecies. -Nord. J. Bot. 5: 127-141. Copenhagen. ISSN 0107-055X.Material consisting of 157 accessions of 69 Finnish Taraxacum agamospecies, representing 7 sections, was grown in an experimental field for comparison of certain botanical and nutritional characteristics. This paper gives the collecting data as well as cytological and reproductive characteristics of the material. The largest section Taruxacum (Vulgariu) was represented by 60 agamospecies, 59 of them triploid (2n = 24) and one tetraploid (T. penicilliforme, 2n = 32). The tetraploid and 37 triploids were chromosome counted for the first time. The diploid sexual species T. obtusilobum from Sweden was included for comparison. Other sections consisted of 3 triploids and 6 tetraploids, 3 tetraploid species of the section Erythrosperma being chromosome counted for the first time. Seedlings with deviating numbers were occasionally found. A banding technique of the chromosomes was developed but it did not allow the exact identification of other than the satellite chromosomes. Species-specific features were found in the flowering phenology and in several pollen characteristics (stainability, mean and variability of the size). There were indications of genetic variation within certain agamospecies in pollen characteristics. Isolated and emasculated (mostly only isolated) flower heads gave mostly a full seed set, which indicates obligate, autonomous agamospermy. Lower seed sets of T. adami, T. dahlstedtii and T. hamatiforme in isolation may be a sign of facultative apomixis in these species, requiring further study.

New chromosome counts and genome size estimates for 28 species of Taraxacum sect. Taraxacum

“…The tetraploid record for T.mediterraneum Soest, 1954 (Cardona and Contandriopoulos 1983; identified as T.balearicum Soest, 1961) does not refer how the taxon was determined. Rousi et al (1985) published a tetraploid record for T.penicilliforme H. Lindberg, 1907 as a member of T.sect.Vulgaria (= T. sect. Taraxacum ), but this species belongs to T.sect.Borea.…”