Possible Clues:

• Things with sticking points
• Prickly pear and barrel
• Prickly pear and saguaro
• Arctic's not right for their cultivation
• Spiky desert plants in plural
• One after prestige when he's away exhibiting plants
• They often break Wile E.'s falls
• They're hardly spineless
• They may be pointed out in the desert
• Before start of play, cheerleader gets flowers