The endangered Nichol's Turk's Head Cactus (Echinocactus horizonthalonius var. nicholii) occurs in scattered populations throughout southern Arizona. The goal of this group is to monitor the known populations of the Nichol's Turk's Head Cactus in efforts to better understand their biology and hopefully steer future decisions in regards to their protection.

Click here to go to the Nichol's Turk's Head Cactus Working Group's website.