The flower must provide a large amount of nectar with a substantial sugar content to support the demanding hummingbird life style. The sugar content should average about 26 percent; amazingly enough this is double what you get in a soft drink. The nectar should not be too concentrated and sticky because hummingbirds rely on a long tube-like tongue to draw nectar into their mouth through what is known as wicking action or the force that brings water up a straw when you stick the straw in a glass.
These flowers tend to have red or orange petals or bracts, which help make them easily noticeable to the hummingbird at a long-distance away and thus case the hummingbird to take notice of it.
The flowers are often long and tubular and therefore a long narrow bill and tongue are required to extract the nectar.
The flowers often hang down and point downward thus providing a hovering bird has the easiest access to it.
These flowers generally have long stamens that will cause the pollen to be deposited on the forehead of the unsuspecting bird.