Pollination Moments

March, 2004

Plant Sex and the Market 

Sexual reproduction in plants requires pollination, that is, the transfer of pollen from one flower to the pistil of another flower.  From the union of the pollen grain and the ovary cells in the pistil comes a baby plant, the seed.  Its swaddling clothes and cradle are the fruit.

Most crops rely on an intermediary to move the pollen around, and bees often act as matchmaker.  It’s been estimated that 1/3 of all of our crops require pollination by bees in one way or another.  Even crops that are not eaten as fruits, such as leafy vegetables, root crops, and herbs, need bees to help create the seed to grow the crop.

Honey bees are our most important commercial pollinators.  An individual honey bee visits many flowers, moving the pollen around as she collects nectar for honey.  But did you know that there are about 5,000 different species of bees in North America in addition to honey bees?  They include the social bumble bees, as well as numerous ground nesting and twig nesting solitary bees: sweat bees, digger bees, carpenter bees, mason bees, leafcutting bees, miner bees and plasterer bees. 

Solitary bees, sometimes called pollen bees, don’t make honey, but they are often as good as or better than honey bees at pollination. Each female solitary bee makes her own nest; there is no division of labor into egg-laying queens and foraging workers as in honey bees and bumble bees.  As a result, most solitary bees are very docile and unlikely to sting.  They won’t risk their life to defend the nest as social species do.

Wander into a garden in the morning and you may hear the high pitched buzz of a digger bee vibrating pollen out of a tomato flower, or you’ll watch a leafcutting bee pick up pollen on the underside of her abdomen as she runs in circles around a sunflower.  You may notice fast flying male squash bees cruising around the zucchini patch waiting to pounce on a receptive young female squash bee when she lands in a flower.  Or perhaps you’ll see a bright metallic green sweat bee collecting pollen on her hind legs from the flowers of a radish or mustard plant that went to seed before you were able to harvest.  You will be surprised at the diversity of pollinators when you look closely.

So, as you roam your local farmers’ market in mid summer or fall choosing the ingredients for a fruit salad, bean casserole, or ratatouille, keep in mind that most of your dinner depends on the labor, not just of the farmer who grew it, but also of bees, both social and solitary.  Think of them as matchmakers for the plant world, and those summer fruits may taste just a little spicier…

Karen Strickler appreciates solitary bees in her market garden and pollination consulting business, www. pollinatorparadise.com.   This essay was first published with the title "Bees: The Vital Link to Plant Reproduction & Human Nutrition", in Harvest Local Foods Guide, 2004/2005, Southern Idaho Edition, published by Harvest, A Division of AgriCents, Limited Co. 2004.