Cover illustration: The inset cover photograph is a cephalium of Melocactus andinus with open flowers and ripe fruits. Studies of the mating systems of this endangered andean cactus and of a related species, M. schatzlii show that hummingbirds are the only pollinators responsible for outcrossing and gene flow events. In their absence, both melocacti set seeds by selfing. See Nassar et al. pp. 29-38.
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