You can’t get much redder than the red of Cardinal Flowers. Their petals act as brilliant red flags beckoning Ruby-throated Hummingbirds, who favor red, to come drink their nectar (and at the same time, pollinate them). Because their chief pollinator has wings and the ability to hover as it drinks, Cardinal Flower has no need for a landing platform, which most insect-pollinated flowers have.
Cardinal Flower has both male and female flowers. Above the red petals is a red tube, at the tip of which the reproductive parts of the flower emerge. First to appear are the male flowers, displaying pollen-bearing stamens. After they die, sticky, Y-shaped pistils extend from the flower, ready to receive pollen. The female flowers thus follow the male flowers (protandry). These flowers mature from the bottom to the top of the spike and you often see both male and female flowers on the same plant (just barely discernible in pictured flower spike).
Male flowers produce more nectar than female flowers, and hummingbirds seem to know this, as they spend most of their time at the youngest, and therefore male, flowers on the top half of the flower spike.
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