IMG 2007-May25 at Grasslands National-Park:  Plains prickly-pear-cactus (Opuntia polyacantha) or Pincushion cactus (Escobaria vivipara)?
2007-May25 at Grasslands National-Park:  Plains prickly-pear-cactus (Opuntia polyacantha) or Pincushion cactus (Escobaria vivipara)?