Thus, the realization of guayule as a commercial crop may finally become a reality. Guayule is a xerophytic perennial shrub that is a dominant element of the limestone bajadas and hillsides of the Chihuahuan Desert of southwest Texas and northern Mexico. The genus Parthenium is unique in the subtribe Ambrosiinae in maintaining flower pollination by insects. Guayule has the highest rubber content of the genus. Guayule can be distinguished from other species of the genus by a layer of T-shaped tricomes on the leaves.
Polyploids are usually larger and more productive.
Guayule is a facultative apomic and can have both sexually and asexually formed seed on the same plant. Recent evidence indicates there may be a temperature or day length trigger for the different types. Asexually formed seeds are predominant in the spring and fall, while sexually produced seed are more frequent in the summer. Rollins has divided the genus into four groups of species based on plant morphology. In this scheme, guayule is most closely related to the species P. rollinsianum .