 Hummingbirds are significant pollinators of cacti. Species showing the typical hummingbird-pollination syndrome have flowers with colors towards the red end of the spectrum, anthers and stamens that protrude from the flower, and a shape that is not radially symmetrical, with a lower lip that bends downwards; they produce large amounts of nectar with a relatively low sugar content. Schlumbergera species, such as S. truncata, have flowers that correspond closely to this syndrome. Other hummingbird-pollinated genera include Cleistocactus and Disocactus.
