Purpose. To reveal the frequency and intensity of callus formation and organogenesis, the effectiveness of microclonal reproduction of various species of the genus Linum L. (Linaceae) in vitro. Methods. For in vitro induction of callus formation and organogenesis, hypocotyl segments of species Linum usitatissimum L. convar. elongatum and convar. usitatissimum, L. tenue Desf., L. bienne Mill., L. corymbulosum Pchb., L. nervosum Waldst. & Kit., L. flavum L., L. campanulatum L., L. perenne L., L. austriacum L., L. grandiflorum Desf., L. strictum L. were cultivated on Murashige and Skoog medium supplementedwith 0.05 mg/l 1-naphthylacetic acid and 1.0 mg/l 6-benzyl aminopurine at 22–24 °C, relative humidity of 60–80%,with 16 hours photoperiod (2500 flux). For microclonal reproduction Murashige and Skoog, White, Gamborg and Eveleigh media and their modifications were used. The measurement results were interpreted by the arithmetic mean, standard error for the sample mean, the leastsignificantdifference and ranked. Results. Different species of the genus Linum to a large extend are capable of forming callus and regenerating shoots under the specified cultivation conditions. The frequency of callus formation for the studied samples on the 35th day of cultivation varied within 81.25–100%, the mass of callus from one explant – 0.21–1.64 g, the frequency of organogenesis – 12.50–100%, the number of shoots – 1.8–7.6 pcs. and the height of the shoots was 0.82–2.12 cm. The following species: L. usitatissimum convar. elongatum, L. tenue, L. bienne and L. strictum were distinguished by a high intensity of callus formation. Intensive organogenesis was pecular to L. tenue, L. bienne, L. flavum, L. austriacum and L. grandiflorum. The efficiency of somaclone obtaining was quite low in L. nervosum and L. campanulatum. In total, for the microclonal reproduction of species of the genus Linum Murashige and Skoog, Gamborg and Eveleighmedia supplementedwith 12.5 g/l glucose were optimal. At the final stages of microclonal propagation, before transferring microclones in vivo, it is advisable to use White medium, which contributes to a high frequency of rhizogenesis. Varieties of L. usitatissimum convar. elongatum and convar. usitatissimum had diffe­rent responses to in vitro culture. Conclusions. The frequency and intensity of callus formation and organogenesis, the effectiveness of microclonal reproduction depended on the genotype of a particular species; therefore it is advisable to select the composition of the nutrient medium and growth regulators for each of them. Some species of the genus Linum have not yet been studied in vitro, so the obtained results allow expanding the scope of their use in practice, in particular in breeding as a new source material with somaclonal variation, interspecific crosses, and ornamental floriculture.

The article represents results of renewal to officinal pilot models of varieties of long-fibred flax and crown flax to bring in to high-yielding properties to the environmental conditions of areas of Forest Ukraine. There brief descriptions of comparative evaluation of identifications morpho-biological indications plants of varieties to place on control pilot models with plants of varieties to place on standard models. There are installed the authentic of descriptions to officinal pilot models of varieties.