Sex in the garden, better known as plant pollination

by Emily Stone Naturalist/Educator Cable Natural History Museum

“Maybe you should write about pollen,” suggested a neighbor as she brushed yellow dust off of her pants. Remembering the film of gold on my car, the cheery lemon color of my dust rag after wiping off the windowsills, and my co-workers’ recent sneezing fits, I agreed. “That sounds like a great idea!”

Pollen is an amazing substance that has an essential place in nature, but it can also mean a mess of dust and allergies in the summer.

First and foremost, pollen is one half of the equation in plant sex. At a recent pollinator garden workshop at the Cable Natural History Museum, natural landscaper Sarah Boles held up the delightful botanical book “Sex in the Garden,” by Angela Overy. “That’s what it’s all about, really,” commented Sarah matter-of- factly. And it’s true—that yellow dust floating through the air is basically sex on the breeze.

A tiny grain of pollen is a surprisingly complex unit that contains the male genes of the plant. A protective coating keeps the pollen dormant until it is safe inside a female of its own species. Inside the pollen grain, proteins, amino acids, fats, and sometimes carbohydrates, lie in wait to fuel the growth of the pollen tube. The pollen tube grows from where the pollen lands on the stigma, down through the pistil to the ovules, and allows the male gametes to fertilize the ovule (egg). In some species, a single cell can grow into 12-inch long pollen tube! In this case, because of the shape of the flower, size does matter.

Some plants can pollinate themselves, but most plants must cross-pollinate with another individual in order to produce viable seeds. Wind can do it sometimes, but that’s also where the insects, and our Pollinator Garden, come in. Flower nectar is like Kool-Aid, and pollen is more like mixed nuts. These tasty bribes entice bees, butterflies, beetles, flies, and hummingbirds to help transfer pollen from flower to flower while they are vying for a snack.

Because plants must have pollen left over from feeding the masses in order to fertilize their ovules, they make a lot of those pesky little particles. Wind pollinated trees especially must make a lot of pollen in order to ensure that some grains get where they need to go. This is the reason my car, my house, and the inside of my nose are all currently dusted with pollen.

Pine trees have male and female cones instead of flowers, and for a few weeks now, the small, papery, male cones have been releasing light, fluffy clouds of “golden smoke.” But inhale away! Pine pollen comes with a whole host of health claims such as “increasing libido” and “skin rejuvenation.” If you don’t want to scrape it off your windshield, you can buy an 8 oz. bottle online for just $69.99.

Some plants, like orchids, have low numbers of sticky pollen grains instead. Their flowers are specialized, and often only attract one type of pollinator. If one bee is visiting one type of flower, it is pretty easy for the pollen grains to get an accurate transport service. This saves the plant energy on pollen production, and saves our sinuses, too.

Common milkweed, another plant, preferred by many nectarivores and pollinators, has a specialized pollen relay system, and therefore is easy on the nose. Milkweed pollen is shaped like saddlebags, with two pollen grains connected by a black line. The whole thing snaps onto a visiting insect’s leg to catch a ride! Then the pollinium falls off into another milkweed flower. Sometimes the flower gets a bit aggressive, and accidentally lassoes the insect it was trying to hire as a courier.

Goldenrod is a bit less aggressive. While it produces plenty of pollen, the grains are big and sticky; good for hitching rides on bees, bad at making you sneeze. The real culprit for late summer allergies is another wind pollinated plant – ragweed. A single plant, with its inconspicuous spike of green flowers, can produce about a billion pollen grains per season. These tiny spiked balls, shaped disturbingly like medieval weapons, float freely on the breeze and into your nose, causing about half of all cases of allergic rhinitis in North America.

Because of its irritating, wind-blown habits, ragweed is definitely not a member of our freshly planted Pollinator Garden. But many other native flowers are. Our hope is that by providing a wide variety of nectar and pollen producing plants, with ample caterpillar host plants as well, our little garden will offset a tiny bit of the native habitat that’s been plowed under or paved over. Habitat loss is the biggest challenge facing most critters these days, but we can all help in our own back yards.

Sometimes, though, good intentions can end up with dire consequences. Large nurseries (including those that supply big box stores) must use fungicides and pesticides to keep their plants looking healthy. One class of those insecticides, called neonicotinoids, has been found to leave residues in the pollen and nectar of treated plants. Those residues can be directly lethal, or just weaken an insect so that something else can kill it. You can help by purchasing plants from a trusted source, and asking informed questions about their growing process.

Pollen may be a dusty, sneezy, annoying part of summer, but it is also a player in the beautiful (and necessary) game of plant reproduction. By cultivating your own pollinator-friendly plot with pesticide-free plants, you can help increase the summer fun of sex in the garden!

Want more resources? The Xerces Society and the Pollinator Partnership have great websites: www.xerces.org, and pollinator.org. You can also watch our garden grow by following us on Facebook!


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