About the cover image:

Thorns, spines, and prickles are some of the physical anti-herbivore defenses of plants. This image shows the long conspicuous spines of the flower head of Echinops polyceras (Asteraceae) from the Ramon Creter, Negev Desert, Israel. For more details, see paper by M. Halpern et al., Plant Signaling & Behavior 2007; 2:503-4.

Courtesy of Malka Halpern and Simcha Lev-Yadun (University of Haifa-Oranim, Tivon, Israel).