Figure 2. Color contrast patterns (no units) across the waveband 400–700 nm, between pitcher lid and peristome (pitcher lid and flared inner section of pitcher body for Nepenthes lowii). (A) Nepenthes lowii (n = 33). (B) Nepenthes rajah (n = 31). (C) Nepenthes macropylla (n = 28). (D) Nepenthes burbidgeae (n = 10). The black bars denote the visual sensitivity regions of the S and L cones (sensitive to blue and green light, respectively) of tree shrew retinas.