Is some pollen more likely to provoke an allergic reaction than others? We are thinking of planting a tree or shrub like a smoke bush Cotinus and would like to know if this means more sniffing in our house when it flowers?

2 Answers 2


Here's one list (source):

10 worst plants for your allergies:

  • Ragweed,
  • mountain cedar,
  • ryegrass,
  • maple,
  • elm,
  • mulberry,
  • pecan,
  • oak,
  • Pigweed/tumbleweed,
  • Arizona cypress.

And from here (See below for more from this source):

  • almond
  • ash (male)
  • Arizona cypress
  • aspen (male)
  • bald cypress
  • black acacia
  • catalpa
  • Chinese elm
  • cottonwood
  • elm
  • eucalyptus
  • fringe tree (male)
  • Kentucky coffee (male)
  • mango
  • mountain laurel
  • mulberry
  • oaks
  • olive
  • Osage orange (male)
  • pecan
  • poplar (male)
  • privet (male)
  • red cedar
  • Russian olive
  • silver maple (male)
  • smoke tree
  • sumac (male)
  • sycamore
  • walnut
  • willows (male)
  • zelkova

This list does include smoke tree.

What I thought was interesting was that most (but not all) of these are inconspicuous flowering wind pollinated plants. Most trees that get insect pollinated don't produce allergies as much because not so much pollen is drifting off the plant. One good seach before buying a plant is how it gets pollinated.

Apparently, at least American smoke trees are insect pollinated, but dioecious. I haven't found anything yet on the pink smoke tree. Again, from here, dioecious trees will cause more allergies because the pollen must be transported farther. If the people at your house suffer from pollen allergies, you might want to plant the trees a good way from the house, although this page says it shouldn't be an issue.

Below is copied information from the allergyware.wordpress.com site for those who cannot access the page.

Only male plants produce pollen, which means that only male plants can produce the symptoms associated with pollen allergies. It's not always easy to identify male and female plants, and in many cases there's no real way of knowing what sex your plant/tree is, since gender is rarely indicated on nursery tags. To further complicate the matter, you can't always tell the sex of a plant just by looking. Here are a few general guidelines to help you sort it out:

Within the world of gardening there are male plants, female plants and plants that are both male and female.

  1. Monoecious plants have separate male and female flowers on the same plant–examples include oak trees (figure A) and corn. The male tassels at the top of the corn plant (figure B) contain the pollen that floats down to pollinate the female ears of corn. Because monoecious plants often rely on the wind to move pollen from the male portion of the plant to the female portion, they are notorious for causing allergies.

  2. Dioecious plants–plants that are either all male or all female–also rely on wind to transfer pollen from a male plant to a female plant.

  3. Many plants, such as roses (figure C), have what's called perfect flowers, which means they contain both male and female parts; as a result, the pollen doesn't have to travel far–this means that these plants rarely cause allergies.

The only way to know the sex of a given plant is to consult references, but there are clues to look for that will give you an idea about whether or not a plant is likely to cause allergies.

  1. Small flowers with little color tend to cause more allergies than large, brightly-colored flowers.

  2. Off-white and greenish-colored flowers cause more allergies than all the other flower colors combined (figure D).

  3. Trumpet-shaped flowers (figure E) seldom cause allergies because their pollen is held deep within the flower.

  4. Fragrant plants–as a rule–don't produce as many pollen allergies, but they may cause an allergic reaction in people who are sensitive to certain odors.


Well technically, anything that flowers and has pollen could be an issue - it would be safer to choose something with double flowers and avoid the pollen altogether, since double flowers either don't produce pollen, or it can't get out or be got at.

I was told the commonest pollen reaction is to grass when it flowers, followed by some trees like birch, but reactions to different pollens seem to be quite individual in some ways, meaning that some people seem to react to any pollen, but lots of others only to very specific ones. Unfortunately, I can attest to that fact myself - I have a significant problem when Tilia is in flower, but not otherwise, unless you count pollution related 'hay fever' affecting nose and eyes, which I find is a problem almost year round here. And you won't find out if Cotinus causes a significant problem when in flower unless you try, its certainly no worse or better than anything else. You could plant the Royal Purple version of this shrub instead - it produces fewer flowers and is a thing of beauty when in leaf, but doesn't have that hazy, smokey effect of the plain green version when in flower.

Really, its down to whether pollen is transported by the wind from particular plants, or whether it sits tight inside the flower unless disturbed by an insect - that's a bit of a big research project!

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.