Experimental scheme. Ark = Arkansas, BC = British Columbia, Mar = Maryland, Mon = Montana, Ver = Vermont, Ach = <i>Achillea</i>, Hel = <i>Helianthus</i>, Poa = <i>Poa</i>, and Vul = <i>Vulpia</i>. HeWei-Ming MontesinosDaniel C. ThelenGiles M. CallawayRagan 2013 <p>Single abbreviations (the left panel; e.g., Ark or Ach) represent one plant grown alone (i.e. no competition), and two abbreviations together (the right panel; e.g., Ark+Ach) represent two plants grown together (i.e. competition). There were 14 and eight replicates for <i>Centaurea stoebe</i> populations (i.e. Ark, BC, Mar, Mon, and Ver) and North American species (i.e. Ach, Hel, Poa, and Vul) grown alone (i.e. no competition), respectively; there were seven replicates for the pair-wise competition.</p>