February 18, 2009

Worst Allergy Plants List

I'm interested in knowing which plants cause allergies because I experience allergies to pollen from grass and several trees. Did you know that repeated exposure to large amounts of allergenic pollen can cause you to develop an allergy to it, even if you don't have one now? Both those people who already have allergies and those who could develop allergies (that pretty much covers everyone!) might be interested in the following list.
I went through Thomas Ogren's "Allergy-Free Gardening" book and picked out some of the plants with a rating of 9 or 10 on the OPALS scale. These are the plants that cause the most allergies. The entire list is huge, so I'm just including plants that are common to temperate climates like mine, plus a few that I remember from my Californian neighborhood. If you live in a mild climate, you'll just have to buy the book to find the worst allergy offenders for your area - including many types of allergenic palms and grasses. Actually, I recommend this book for every gardener and designer.
The plants are listed alphabetically by latin name with common names in parenthesis. In many cases just the male forms are the offenders, as females don't produce pollen to cause allergies. Sorry I didn't do the italics thing but I just didn't have the patience for it on this long list.

Acacia (wattle, mimosa, whitethorn)
Acer negundo 'Aureo marginatum', 'Baron', 'Violaceum' (male box elder)
Acer rubrum 'Autumn Spire', 'Tiliford' (male red maples)
Acer saccharinum (male silver maple)
Agrostis (bent grass, redtop)
Ailanthus (stink tree, tree of heaven)
Alnus (alder)
Ambrosia (ragweed)
Anaphalis (pearly everlasting)
Artemesia (dusty miller, sagebrush, tarragon, wormwood)
Aruncus sylvester
Broussonetia papyrifera (male paper mulberry)
Callistemon (bottlebrush)
Carex (sedge)
Carya (hickory, pecan)
Chionanthus (male fringe tree)
Corema (broom, crowberry, poverty grass)
Cryptomeria japonica (Japanese cedar)
Cupressus (cypress)
Cynodon dactylon (Bermuda grass)
Elaeagnus angustafolia (Russian olive)
Elaeagnus pungens (evergreen silverberry)
Fescue glauca (blue fescue)
Fraxinus (male ash tree)
Gymnocladus dioica (Kentucky coffee tree)
Helenium autumnale (flowering sneezeweed)
Juglans (walnut, butternut)
Juniperus (male juniper, cedar, habbel)
Laurus nobilis (male bay, sweet bay, sweet laurel)
Lycopodium (club moss, ground cedar, princess pine)
Mangifera indica (mango)
Morus (male mulberry)
Olea europaea (olive)
Pennisetum setaceum (fountain grass)
Phalaris (canary reed grass)
Phleum (timothy grass)
Platanus (sycamore, plane tree, buttonball tree)
Poa (Kentucky bluegrass) *if mowed often it won't produce pollen
Podocarpus (male fern pine, yew pine)
Populus (male aspen, cottonwood, poplar)
Quercus (evergreen oak, ie coastal live oak)
Rhamnus (buckthorn, coffeeberry)
Rhus (sumac, poison ivy, poison oak)
Salix (male willow)
Schinus (male pepper tree)
Senecio (cineraria, natal ivy, german ivy, wax vine)
Thalictrum (meadow rue, buttercup)
Zelkova (Japanese zelkova)

After perusing the list, do you notice any plants that have given you allergy symptoms? Are there any that you might need to remove from your landscape? When we lived in California, I often walked past a long row of olive trees on my morning walks. By the end of the row, I usually had a headache, but didn't attribute the problem to the olive pollen until I reread Ogren's book and saw that olives are rated as a 10. I turn to his reference book as I'm considering new plants - especially trees - for my landscape. I'm willing to take medicine and put up with the sniffles in order to continue to enjoy time outdoors, but of course I'd like to reduce the problem by reducing pollen levels in my yard and community.

Professor Ogren has released another book, The Allergy-Fighting Garden: Stop Asthma and Allergies with Smart Landscaping, available here.


  1. As a child and as an adult I moved multiple times. I found the worst allergic symptoms I had were when we lived in New York in the Hudson River valley. Here in southern Virginia I pretty much take allergy meds year round.. to quote Rosanne Rosannadanna...It just goes to show, it's always something.

  2. I'm allergic to Oaks (Burr, Red, White), Maples of all kinds, June grass, various fescues, Kentucky bluegrass, Chamomile, and of course, Ragweed. In other words, I generally miserable from March through November. If it spreads by the wind, I'm probably allergic to it.

  3. Oh yes. The dreaded hay fever season. Here in western Oregon's Willamette Valley the conditions are conducive to grass so, opportunists that they are, farmers have laid claim to literally thousands of acres for growing grass, selling the seed for lawns and fodder. Late June and early July is when the grass begins to bloom. You can see "dust" clouds of pollen swirling in the wind. Needless to say it's not a happy place for allergy sufferers. About three summers after moving here, I developed horrific allergies that continued for two more summers and then, poof. Gone. Some residents actually wear surgical masks it's so bad. So I guess what I'm trying to say is, sometimes no matter how many allergen free plants you choose, you're stuck with environmental conditions outside of your control.

  4. I agree with MMD. If it spreads by wind, you might well be allergic. So, try to get female trees. Consider staying away from grasses. And load up on all the beautiful shrubs, perennials and annuals with lots of color that the bees and the butterflies love.

  5. One of those posts filled with good information that I'd still rather not know. It feels like the list of plants that are ok to use based on water, invasiveness, culturally appropriate, allergic, just gets longer and longer.

    This past week, I needed some fast growing, evergreen low water screening trees for an odd shaped property. I recommended Acacias, warning my clients that if they were prone to allergies, this trees could be problematic. The clients wanted to know if their neighbors would complain. "Possibly" was my response. "Good, we don't like them." So, I guess it all depends on your point of view.

    Regarding Olives, an exception is the Swan Hill cultivar as it is the only truly fruitless Olive. It also has a beautiful shape, but it's very pricey.

    1. 'Swan Hill' Olive is sold as non-flowering, non-fruiting and non-allergenic, BUT, it does flower and it does produce allergenic pollen. There are no allergy-free olive trees.

  6. I see a lot I'm allergic to. The Olive trees get me badly. We lived in California around the Olive trees and I couldn't breathe. I was glad when we moved. It was a pretty place but my health was bad while there.

  7. I have many of these but never a problem. I consider myself very lucky as allergies are not fun. Here there seems to be a major issue with grasses and trees more than the perennials.

  8. Acacias...even if they didn't like their neighbors, what a mean thing to plant. Now, since like you said, heavy exposure over time can trigger (new) allergies, then maybe they'll end up with acacia allergy themselves after awhile. It would serve them right.

  9. I declared war on ragweed here years ago. I pull every plant I see. Wouldn't it be great if all the ragweed got pulled out before they ever got a chance to flower?

  10. how interesting - what do these plants have in common I wonder? Do they produce lots of pollen? Or is there a special quality in their pollen? Even if we don't (currently) have allergies it would be good to reduce these plants in the general environment.

  11. Alright, I needed to get my Amazon order up to $25 for the free shipping so I ordered the book. You've recommended this book before, so if you are getting some kind of kickback, go ahead and let the author know you've roped another one in.

  12. I'm sorry but not surprised to read that so many other gardeners suffer from allergies. Thank heaven for meds, eh?
    Susan, I am definitely not getting a kickback from Amazon, though my poor nose will benefit if more people read this book and follow its advice. You notice that I didn't even give into the temptation to put AdSense on my blog and earn an extra buck-fifty a month from annoying ads :-)
    Catmint, these plants do have much in common. The worst allergy plants are generally wind-pollenated, so their pollen is lightweight and dry to allow it to travel long distances and stick well to damp surfaces, like stigmas (the female plant part) and nasal membranes. They also produce copious amounts of pollen. Since their flowers are not meant to attract insects or birds, they're often tiny with pale coloring - in fact, many people don't even think of these plants as flowering at all.

  13. what about a plant redish pink that looks just as a rose?

  14. I've just come on this old blog article and wanted to make a comment or two: Per "Regarding Olives, an exception is the Swan Hill cultivar as it is the only truly fruitless Olive. It also has a beautiful shape, but it's very pricey."
    No, 'Swan Hill' is not the only fruitless olive cultivar sold, there are several others, BUT the point I want to make is that all of them, including 'Swan Hill', that ALL of them produce male flowers and pollen, and that it is extremly allergenic pollen.
    The growers of this selection cheat, lie it you will, when they make it sound like it is an allergy-free tree...it is not!
    Another comment:"Catmint" asked if there is a difference in the allergenicity of certain types of pollen? The answer is a loud YES, some pollen grains are hundreds of times more allergenic than others. The catmints, by the way, often produce plants that are all-female, and thus produce no pollen at all. These all-female catmints have rich nectar sources, and bees and small butterflies love them.
    I am the author of Allergy-Free Gardening, and of the newest book, the Allergy-Fighting Garden...and of course, your VW host here....she gets no kickback on book sales. My best to her, and all readers. Tom Ogren

    1. Well I'm honored to have a comment from you, Mr. Ogren! Forgive me for being slow to publish it as I have been taking a break from blogging for a few months. My garden is a healthier place thanks to your book, and I'm sure many others are grateful for your research as well.

  15. I could not refrain from commenting. Perfectly written!


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