Ecological Study of Carduus pycnocephalus L. Weed and Associated Species in Hamedan Province, Iran

Slender thistle is one of the species of Asteraceae. It is native to: In the Mediterranean region of southern Europe, North Africa, West Asia, East Europe, Caucasus and the Indian subcontinent are scattered. This study carried out for determination associated species on intraspecific variation of Carduus pycnocephalus L. (Italian Thistle) in Hamedan Province (Iran).In this order, vegetation studied to D.S.S method (Determination of Special Station). Based on, 14 special stations for this species were determined. In this investigation, 59 plant species distinguished as associated species that belonging to 53 genera and 19 families. Among the families, Asteraceae and Poaceae have many species. Most of this species are weed plant. The most life form spectrum showed Therophyte that reflects the region's dry climate. Spectrum of plant species is as follow: Hemichryptophyte forms of the plants indicate the possibility of adaptation of Maditerranean and cold temperate affected them. Decreasing of Chamephytes and Hemicryptophytes species and lacking geophytes Indicates a weakening of the vegetation in this area.