Q. I want to plant a nice shade tree in my back yard. It seems like every tree I consider has its pros and cons. I am most concerned about the mess—I have installed a beautiful clay paver stone patio that we use like another room in the house. I love Oaks but I don’t want acorns all over the patio. I love Maples, but I don’t want those helicopter things falling either. A medium-fast grower would be great. I live in Minneapolis. (zone 4b, I think.) Any advice? THANKS! Mark Jacobson – Minneapolis, MN
A. I am inferring from your question (since you mentioned maples and oaks) that you want a deciduous tree that provides shade in the summer and then allows light during the winter. So I assume that you are all right with leaf raking duty but just not dealing with a trees fruits/seeds. Since fruit/seed comes from female flowers (or the female part of a complete flower) selecting a species of tree where the trees’ gender is split by individuals would be useful. This setup in a plant is called dioecious (Greek for two houses). So one tree has male flowers only and the other has female only. Oak and Maple (as well as many other well known trees) are monoecious (you guessed it “one house”) so both flowers are present in each individual. There can be either both male and female flowers on the plant or a complete flower that contains both the male and female parts (like a hermaphrodite). The Ginkgo (Ginkgo biloba) is a dioecious shade tree whose cultivars are asexually propagated (cloned) from male trees. This has been propagated this way because the female fruit stinks to high heaven! Another alternative is to find sterile trees that don’t produce fruit or seed like Marshall’s Seedless Green Ash (Fraxinus pennsylvanica) as well as many of the other ash hybrids that are seedless. Now that you know to ask for male or sterile cultivars of shade trees you can also visit your local nursery to find out what selection is available to you locally.