Russian dandelion

The Russian dandelion, which may contain up to 10% of good quality rubber. The plants are harvested and the rubber obtained in the manner of sugar from sugar beet. It is claimed that the yield per acre approaches that of plantation rubber. 

Taraxacum kok-saghyz Crimea Shrub Russian dandelion rubber... 

Polyisoprene occurs in other plants, some of which have been of commercial significance, such as the Russian dandelion and the Mexican guayule shrub. The well-known properties of natural rubber are dbplayed only at temperatures above the glass transition temperature, which is -7(PQ below that temperature it is a brittle glass. Every amorphous pofymer, whether synthetic or natural, providing it is cross-linked, displays comparable properties above its glass transition temperature. These properties are, stated briefly ... 

J. B. van Beilen and Y. Poirier, Guayule and Russian Dandelion as Alternative Sources of Natural Rubber , Critical Review Biotechnology, 2007, 27, 217-231. 

Another possible future source of natural rubber is from the Russian dandelion known as Taraxacum kok-saghyz. These plants can be planted and harvested annually, which would enable one to adjust more effectively to the large swings in supply and demand. 

FIGURE 4.24. NR-producing plants (Russian dandelion photo reprinted with permission from Maureen Whalen, USDA-ARS). 

Other sources of cis-polyisoprene are also interesting, and number in the hundreds. The white sap of milk weed and dandelions are actually a rubber latex. During World War II the Russians were much interested in extracting the rubber from dandelions, especially the roots, which contains 1.25-5% rubber. 

---