Russian dandelion (Taraxacum kok-saghyz): one more example of overcollecting in the past?

Taraxacum kok-saghyz is a rubber producing plant that once was a strategic source of natural rubber in Soviet Union but with no current usage as a crop species. In this paper we 1) review the existing literature on kok-saghyz, most of which exists only in Russian; 2) describe kok-saghyz germplasm collecting undertaken in 2005 and 2006 and results of analysis for rubber content in the germplasm sampled. We found the kok-saghyz plants to be very rare in the area where they were common in the past and having very low rubber content. A reason may be overcollecting in general and especially of plants with high rubber content in the 1930ies to 1950ies of the last century.