I can attest from my personal gardening experience that corn poppies (Papaver
rhoeas) are an excellent and attractive source of pollen.  They produce large
quantities of pollen, and are visited by many varieties of bees, but most
especially honeybees, to judge by my observations of my own plants.  Often,
several bees can be observed "wallowing" in the poppy stamens, simultaneously.
Other plants, such as squash, produce larger amounts of pollen, but do not
seem to be as attractive to bees.  (I notice that the bees seem to have
difficulty finding the male squash blossoms before they close up.)  I would
recommend poppies, as they are attractive, produce abundant pollen, produce
large numbers of flowers in a small area, and are ridiculously easy to grow.
(Just throw out a few handfuls of seed, and you'll have poppies for years!)
 
Jane Beckman   [[log in to unmask]]