Pollination Syndromes

Pollination syndromes are a phenomenon witnessed in many species of plants. Essentially, a pollination syndrome entails a plant possessing traits that perfectly suit it to being pollinated by a particular type or species of pollinator.

A good example is the hummingbird pollination syndrome. These plants are typically red, tubular and have large amounts of dilute nectar.

http://upload.wikimedia.org/wikipedia/commons/9/93/Scarlet_gilia_Ipomopsis_aggregata_branch.jpg

Scarlet gilia, Ipomosis aggregata has a hummingbird pollination syndrome.

How bees see flowers

Bees, unlike humans, can see UV light.

So while we see a crocus like the first picture, bees see it like the second!
http://img.dailymail.co.uk/i/pix/2007/08_01/CrocusDM0708_468x643.jpg 

The varied coloration functions as guides for bees, leading them to nectar.