The flowers on this spike are young, and mostly staminate (male) at this point. The arcuate grayish projection from the summit of the flower contains the sexual parts, and when the flowers are new they extend a brushlike clump of stamens capped by the anthers which contain pollen.
The hummers routinely visit cardinal-flowers, which apparently are prolific nectar-makers. The nectaries are deep within the corolla, forcing the bird to plunge its bill far into the flower. In the process, the top of its head makes contact with the downward-curving sexual flower parts. If the flower is in the male phase, pollen will be deposited on the hummingbird. If in the female phase, pollen from some other flower - hopefully from another plant - will transfer from the bird's head to the stigma, and thus pollinate the flower and allow production of fruit.
The coevolution of cardinal-flower and hummingbirds is a particularly showy example of the myriad ways in which plants have forged alliances with animals.