OBJECTIVETo determine cytology chromosome numbers, doubling, type, karyotype formulae of seven kinds of Taraxacum.

METHODSeven kinds of dandelion in Northeast China were karyomorphologically studied by conventional pressed slice method.

RESULTThe interphase nuclei and prophase chromosomes of all species were found to be of the complex chromocenter type and the interstitial type respectively. The somatic chromosomes showed polysomaty within or among species. The range of chromosome numbers was from 16 to 32, and 24 was preponderant. It is firstly confirmed that the chromosome numbers of T. ohwianum were 2n = 2x = 16 of and those of T. variegatum 2n = 4x = 32 of, and those of other five kinds of dandelion 2n = 3x = 24. Karyotype was diverse and consisted of metacentric, submetacentric and satellites. The relative lengh of chromosome varies from 3.74 to 27.68, asymmetry index was between 59.68% and 64.02%; The karyotype type was belonged to "1A", "2A"and "2B" extensively, to ensure the T. ohwianum and T. variegatum evolutional karyotype type and genetic inheritance pattern.

CONCLUSIONAccording to results of the cytology karyotype we suggest that T. antungense and T. urbanum could be merged, the result was consistent with Flora Reipublicae Popularis Sinicae (FRPS). This paper reports systematically cytology karyotype feature of seven kinds of dandelions in Northeast, provides the cytology theoretical basis for further development and use of the resource and genetic breeding research of dandelions.