The article presents the biological features of Arctium tomentosum Mill. in natural and sowing conditions, the changes in morpho-anatomical structure of vegetative organs in ontogenesis. The growth rate of the germinal root was quite active, and the formation of many lateral roots was observed at the juvenile stage of life. There was an increase of the neck of the germinal root in the immature state, the formation of primary and secondary lateral roots in length, and an increase in the level of growth of the germinal root in the virginal age state. In the generative state, in the second year of life, the lateral roots form two distinct layers. The seed shell in the natural environment is lamellar, without protein, the seed is well ripened. In the next juvenile state, it was observed that the components of the xylem and phloem were not fully formed in the leaf-like cotyledon, with an underdeveloped mesophyll, of a homogeneous type. The first anatomical features in the root structure have been clarified. The size and shape of mesophyll cells are stable, columnar and loose parenchyma are determined, conductive tissues are formed. The anatomical structure of the root undergoes a period of over-development. In the generative state, the size of the central cylinder increased in the structure of the root, the layer of cutin thickened on the leaves, and the layer of columnar mesophyll containing chlorophyll grains increased. There was an accumulation of idiotic cells and needle-like calcium oxalate druzes in the root.