Allergy Alert

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:

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.

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.

1. Avoid planting the most notorious pollen producers, like goldenrod (figure F) (see list below).
2. Create as much diversity in the garden as possible.
3. Stay out of the garden on windy days.
4. Avoid planting pollen-producing plants near areas where you spend a lot of time or near windows that you like to open on nice days.
5. If you're allergic to grass pollen, cut the grass and weeds before they have time to flower.

Mold is another cause of allergies, and you can usually find plenty of it in the garden. The good news is that mold can be somewhat controlled by making sure that your landscape gets plenty of sunlight and good air circulation. The bad news is that one of the key features of any good garden--the compost pile--is also a notorious source of mold. Molds are beneficial catalysts in the decomposition process, so have someone else turn your pile and spread your compost if you're allergic to mold.

Worst trees and plants for allergy sufferers:

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

Allergy-causing flowers and grasses:

Artemisia
Bahia grass
Bermuda grass
blue fescue
bluegrass
buttercup
castor bean
centipede grass
fountain grass
gamma grass
goldenrod
orchard grass
sedge (Carex)
Timothy grass