ABSTRACT
Compositae represent the largest family in the Siberian flora. Its members are extensively distributed in all the zones, from the Arctic to the desertified steppes in the south. These are annual or perennial plants, rarely subshrubs. As a rule, they do not form their own plant communities but, in many habitats, specially in the steppes, are active members of communities, e.g., wormwood, Filifolium and Saussurea. A large number of Compositae owe their propagation to human activity. Some are harmful weeds like yellow thistle (Cirsium setosum), field sow thistle and common groundsel (Senecio vulgaris) while others are roadside plants and plants inhabiting abandoned natural human habitats: mayweed (Matricaria), common dandelion (Tara xacum officinale), common chicory (Cichorium intybus) and others.
