Spiny plants (5)
I believe the answer is:
cacti
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">spiny plants</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for cacti that I've seen before include "They're decidedly prickly" , "growing group" , "Prickly plants" , "Spiny desert plants" , "Plants of dry regions" .)