, Volume 86, Issue 1, pp 70–75 | Cite as

Thorns as induced defenses: experimental evidence

  • A. V. Milewski
  • Truman P. Young
  • Derek Madden
Original Papers


We report evidence from controlled experiments that long straight thorns deter herbivory by browsers. Cut branches of three woody species that had their thorns removed suffered significantly greater herbivory by a tethered goat than did paired intact branches. Branches on living Acacia seyal plants that had their thorns removed suffered significantly greater herbivory by a wild population of free-ranging giraffes than did intact branches on the same plants. These differences in herbivory resulted in long term losses of branch length in clipped as opposed to control branches. In addition, branches within reach of giraffes produced longer thorns and a greater density of thorns than did higher branches. These results imply that increased thorn length is an induced defense.

Key words

Induced defense Spinescence Thorns Giraffe Herbivory 


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Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • A. V. Milewski
    • 1
  • Truman P. Young
    • 1
  • Derek Madden
    • 1
  1. 1.School for Field StudiesBeverlyUSA

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