Two Houses: Dioecious Plants, part 1

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The street I grew up on was lined with Sycamore trees. Their leafy masses were a delight in summer and always produced some good-natured grumbling during fall raking. These were small city lots and as time moved on problems developed. Blocked sewer lines became common and sidewalks started to lift and shift, making walking difficult and potentially hazardous. The repair costs were a burden for most owners so my family and most of the other homeowners had their trees removed. The city proposed replanting with new trees of a different type and most of us accepted their offer. The trees they planted were selected for their smaller mature size and evergreen leaves. The homeowners were satisfied but something was lost and the feeling of a neighborhood was gone, at least to my eyes.

After several years of living with the new trees it was apparent something was different with ours. Most of the others remained tidy, growing modestly and seemed unchanging from year to year. Ours insisted on being different. It grew faster than its street mates, always suckering madly. Its branches were longer, its leaves more lustrous and luxurious. The reason it was different was revealed when pods appeared and dropped on everything below it. The city had planted Carob trees and ours was one of the few females around.

Whether for beauty or fragrance or the fruit that may develop, we enjoy flowers for many reasons. Their real purpose, however, is reproduction and continuance of their genetic lines. Most plants have flowers with pollen and seed-bearing parts, their stamens and pistils, in one flower. These types of flowers are described as “perfect”.

Imperfect flowers are unisexual, being either staminate (pollen-producing) or pistillate (seed-producing) but not both. Monoecious (moe-NEE-shus), meaning one house, have separate flowers on the same plant. My alders already have small pollen-laden catkins waiting for spring and their assignations with the cone-like females. Corn, squash, calla lilies and other aroids, and tuberous begonias are common examples.

Dioecious (dye-EE-shus), meaning two houses (see the pattern) are imperfect flowers on different plants. This is a very small group in the floral kingdom and you have to wonder why this was thought to be the path for survival and continuation of their lines. But it works and the plants are still with us. Allow me to introduce you to some of these odd plants. Part 1 of a 6 part series. Tomorrow – part 2

About the Author

I started in 1977 growing plants at wholesale nurseries and a wholesale seed company in California. In 1992 I started volunteering (in the nursery, of course!) at Strybing Arboretum in San Francisco where I met my wife. My wife is originally from upstate and we moved here in 2002. It took at least two years of living here for me to fully understand our property and to take advantage and work with our microclimate. Although growing zone maps show us to be in 5, we are realistically a 4b. I am inordinately proud, in a smarmy kind of way, of how many of the plants we brought with us have thrived. Coming from a zone 9 has been quite an adjustment for all of us. But we are thriving and enjoy the beauty and what the land gives us everyday. USDA Hardiness Zone: 4b/5a Location: rural; Central Leatherstocking near Cooperstown, New York Geographic type: riverine valley Soil type: Chenango alluvial – shallow clay and highly stony Experience level: 28 years professionally wholesale and retail, no longer in the business Particular interests: native plants and ecosystems, flowering and berry producing shrubs, home-grown foods, maples, birches, willows, ornamental grasses, filipendulas, iris, ligularias, persicarias, asclepias, artemisia, asters, arisaemas, hardy geraniums, euphorbias, eupatoriums, origanums, lysimachias, eryngiums, lilies, and visiting nurseries

When dealing with frost it is always best to be paranoid. In the spring never think it is too late for one more frost to come. And in the fall never think it too early.

~Rundy in Frost

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Jim February 8, 2012, 2:07 pm

I learned that the sumacs here are dioecious. Small groves of sumac along our roadsides were either fruiting or completely non-fruiting, which, my research showed, meant that each entire little grove was male or female. Pretty neat to see.

Patrick's Garden January 3, 2012, 1:58 pm

Hey Craig,
Good, meaty info here. I’m aware of typical situations with hollies and fruit but hadn’t6 thought about shade trees and the like. Looking forward to tomorrow.

KL January 2, 2012, 11:03 am

Very interesting and informative article. I would be looking forward to reading all the other parts. In your profile, you have mentioned that you are proud that most of the trees your brought have survived. Do you mean that trees from California are surviving in upstate NY climate? If yes, that’s absolutely incredible. Wow.