pollen – The Garden Professors™

Pollination strategies can lead to allergy woes

This article was originally published in my weekly newspaper column in the Charleston Gazette-Mail. Articles are archived at wvgardenguru.com.

A quick selfie with President Gee. He's perfected the art of the selfie. — A quick selfie with President Gee. He’s perfected the art of the selfie.

A few weeks ago I made my way to South Dakota for the annual meeting of the National Association of County Agricultural Agents (where fellow GP and I made the rounds at the trade show scrutinizing wacky products). It is a fun conference made even more special this year by the fact that WVU President E. Gordon Gee was in attendance as the conference co-keynote speaker and recipient of the Service to American/World Agriculture award. But I digress…..

Two days into the conference something wasn’t quite right. I kept feeling worse and worse, and by Wednesday I was confined to my hotel room (save for a venture out to the conference banquet for dinner). I would not have been functional for the rest of the trip save for the kindness of a co-worker who went through the pharmacy red tape to procure and deliver “the good stuff” to my hotel room.

I thought I had a sinus infection at best (I get them often) and the flu at worst (yes, it was really that bad). But guess what — I’m just really allergic to South Dakota. Two days after my return, I was nearly back to normal (well, my normal, anyway).

Those who know me know that I suffer from the occupational hazard of allergies. Irony dictates that my allergies are only to about two dozen plants and two molds (that occur in mulch/compost). Lucky me!

Lots of corn surrounding my hotel in the outskirts of Sioux Falls. — Lots of corn surrounding the outskirts of Sioux Falls.

My best guess is that I had a reaction to the corn pollen of South Dakota. It makes sense — while we do grow some corn here in West Virginia, the Mount Rushmore State boasts an estimated 4.75 million acres of corn. I don’t think I was tested for corn pollen allergies, but since corn is not a major crop here, it may not be part of the common test.

I tell this story not for sympathy (well, OK, maybe a little) but it brings up a good illustration about pollination strategies of plants.

Scanning electron microscope image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis).

You see, plants like corn rely on chance and wind to spread their genes around. In corn, the pollen drops from the male flowers (the tassel on the top) to the stigma of the female flower (the end of the silk sticking out of the cob). The process relies on lots of pollen being released into the air, since there is a good chance that a lot of it will miss the target. Corn pollen is usually heavy, therefore it doesn’t blow too far from the plant (unless there is lots of wind).

This is why you don’t get a good corn crop if you don’t have a big block of corn in the garden — just one or two rows doesn’t drop enough pollen to pollinate all the flowers. When the silks don’t get pollinated, you’ll end up with incomplete cobs missing kernels. This can also happen if the corn is in bloom during a long period of rain — the rain washes all of the pollen off before pollination can occur.

Most of the major allergen-producing plants are wind pollinators — trees, grasses, ragweed. They all release copious amounts of pollen into the air hoping for it to land in the right place.

Some plants still rely on pollen getting moved from plant to plant or flower to flower, but they remove the chance involved with wind pollination. These plants have a stickier pollen that stays on the flower and waits for something to come along and move it — a bee, a butterfly, a moth, a hummingbird, etc. These plants hold on to their pollen and have the more directed approach of getting a courier to make a direct delivery of their pollen between flowers.

Since these plants don’t leave the pollination to chance, they generally produce less pollen. Some good examples are fruit trees (apples, peaches, pears), sunflowers, squash, goldenrod and roses. Since they don’t release it into the air, they usually aren’t considered major allergens.

Still yet, some plants want to take no chance with their next generation. Self-pollinating plants don’t rely on pollen being spread to different flowers — they take care of business themselves. These plants are perfectly fine without crossbreeding with other plants.

Sometimes, these plants are so dedicated to self-fertilization that they make it difficult for the pollen to leave the flower. Bean flowers have a lower lip that curves upward to protect the reproductive parts inside. Tomato flowers are nearly completely enclosed. You may see bees going from flower to flower, but their search for food is in vain — they can’t get into the flower. Their buzzing does help dislodge the pollen inside the flower, but they don’t have access to spread it around. Producers that grow tomatoes in greenhouses where there is no wind to knock the pollen loose either buy boxes of bumblebees to release in the greenhouse, or use something like a vibrating toothbrush to help the flowers self-pollinate (no joke).

This is why you can plant two different tomatoes just a few feet apart and not have them crossbreed, but you would have to plant squash up to two miles apart (or protect the flowers) to guarantee that you get the same variety if you plan on saving seeds. This is why the most commonly saved seeds, at least in this area, are tomatoes and beans — they are easy to guarantee that you won’t get something other than what you plant.

So if you learn anything from this article, check out how plants pollinate before you save their seeds, and take plenty of allergy meds with you if you go to South Dakota.

Finding agreeable things not sought for

As a graduate student at the University of Georgia many years ago I took a course in research methods. One of the discussions that stuck in my mind all these years centered on the word ‘Serendipity’. The classic definition of the word is “the faculty or phenomenon of finding valuable or agreeable things not sought for.” As scientists we rely heavily on the scientific method as a systematic method of inquiry to make new discoveries. But we also need to need to keep our eyes and minds open to serendipitous discoveries along the way as well.

So what got me thinking about serendipity? A few weeks back I visited a Christmas tree grower in northern Michigan with Jill O’Donnell our state-wide Christmas tree educator. The grower called us in because he had some questions about some unusual trees in one of his Fraser fir plantations. And, not only were the trees unusual, they were gorgeous. The only question was; what were they? The plantation originated from seed the grower had collected himself from some older Fraser fir trees he kept as a seed orchard. He sent the seed to a large forest nursery in the Northwest, which grew the seedlings and sent them back to him. The grower wondered if seed of another species could have been introduced in the process. Possible, I told him, but not very likely. Nurseries that are serious about contract growing are meticulous in keeping seed lots separate – few things are worse in that business than sending the wrong seedlings. Plus, I’ve worked with many species of fir and this was one I didn’t recognize. The trees had many characteristics of Fraser fir but also had attributes of concolor fir; long bluish needles and a slight hint of citrus scent when the needles were crushed. Many fir species can hybridize and all I could think was these trees had to be hybrids. “Are there any mature concolor firs near the seed orchard?” I asked. The grower brightened, “Actually there’s a group of older concolors about a half mile up the hill from the Fraser fir orchard.” We jumped in his pick-up and visited the concolor firs. Many of the trees had cone stalks indicating they were reproductively mature and could produce pollen. Conifer pollen can travel for miles so it’s reasonable to expect that some of the concolor pollen could reach the Fraser firs, which were downhill and downwind based on the prevailing winds in the area.

Excellent tree form of the mysterious hybrids

So what’s next? There are several reasons to follow up on this serendipitous discovery and try to make some additional crosses. First, as evidenced by the photos, the trees look fantastic. Second, Fraser fir and concolor fir are each great trees but they also have some liabilities. A downside of concolor is that they break bud early and often suffer late frost damage – Fraser’s break bud late. Fraser fir need acidic, well drained soils – concolor fir can grower on a broader range of sites. It’s possible that the hybrids will have intermediate characteristics that would make them ‘the best of both worlds’.

Foliage close up

The only thing left is to decide what to call the hybrids. Nurseries like to combine common names. So, Craser fir? Froncolor?

Plastic grass and organic gardens

One of the best cures for writers’ block for a Garden Professors is to spend a little time in front of the tube watching home gardening shows. Now, to be sure, there are useful nuggets of information that can be gleamed from an hour or so of gardening or landscaping on HGTV or PBS Create. But there are moments when I just stare at the TV in disbelief and go, ‘Have these people lost their frickin’ minds?’

A recent case in point, a half-hour gardening show devoted to installing an ‘allergy free’ backyard for a youngster, we’ll call him Billy, with environmental allergies. Let me state up front I am in no way minimizing the seriousness of environmental and related allergies. I suffer wicked seasonal allergies (yes, I know, poor career choice) and I have several close friends whose children have severe allergies. I realize allergies can seriously affect quality of life and, in the cases of some food and insect allergies, can be a matter of life or death. And I realize that a parent will do just about anything to keep their kid healthy. Nevertheless, some of the practices promoted on this show strained all manner of credibility.

First, since Billy is allergic to grass, the landscaper replaced all of the grass in the backyard with synthetic turf. Grass allergies are among the most common allergies but what is it about grass that most people are allergic to? Pollen. According the National Institutes of Health just keeping grass mowed is a simple preventative measure to reduce grass pollen. Synthetic grass may have issues of its own with molds and there are remaining uncertainties regarding the safety of the used-tire derived crumb rubber used in some fake turf. And if Billy has issues with pollen, I saw a much bigger problem looming like an 800 lb gorilla as the camera panned back from the picture-perfect synthetic lawn: Trees, specifically dozens of oaks and pines in the woodlots beyond the backyard. I joined the show part way through but the overall landscape looked like the Southeast, perhaps Georgia or the Carolinas. Even if the fake turf does reduce grass pollen in the back yard, Billy will scarcely notice as a yellow-green cloud of tree pollen envelops his house every spring.

Next, in addition to wanting a place to play, Billy wanted a vegetable garden. Actually, given Billy’s obvious disinterest during this part of the show I don’t think he was really that interested in vegetables but the producers knew they couldn’t fill a 30 minute show with just fake turf. Assuming Billy really was into vegetables the solution, of course, was an organic garden. Why an organic garden is a panacea for allergy sufferers was never explained in the show; apparently pollens and molds don’t hang out in organic gardens. The choice of vegetables was curious as well. Billy got to plant squash and watermelons; guess no one bothered to tell Billy that cucurbit allergies are among the most common food allergies for people predisposed to pollen allergies. For good measure, Billy got to plant some corn – doubt that could ever produce any pollen…

Bottom-line: take the info from the garden shows with a grain of salt and consider the source of the information. Often times these shows are limited to whatever local source they could dredge up. Do you really want to rely on a landscape contractor to make decisions about your child’s allergies and health? Enjoy the shows but keep your skepticism handy and be ready to do some fact checking on your own.