Over The Fence Newsletter Bucks County Cooperative Extension

Native vs Non-Native BY Scott Guiser

Can't we all just get along? In the plant world…apparently not. In the text "The Plants of Pennsylvania" it is estimated that one-third (about one thousand) of the plant species in Pennsylvania are not native. Some of these non-native species become invasive and dominate their new environment at the expense of the natives. Japanese stilt grass (Microstegium vemineum) is an invasive, annual grass species that has deviled Bowman's Hill Wildflower preserve and many other shady spaces in Bucks County for years. Japanese knotweed (Polygonum cuspidatum) marches through landscapes and roadways and shrugs off attempts to restrain it. Even Norway maple, a fine street tree in many respects, has become weedy in certain locations. Invasive, non-native plant species displace native plants and millions of dollars are spent managing them every year. Recently, the "invasives" problem has gotten lots of attention. Task forces, symposiums and websites devoted to the subject are plentiful.

But it is important to realize that "non-native' does not equal "invasive". Let me toss out a few names for you….Apples, peaches and pears. Non-native. Wheat, oats, soybeans. Non-native. Heck, depending on where you draw the line, someone might even consider corn to be non-native. Sure it's native to this hemisphere but the experts figure it probably started off in South America. Is it native? Same story for our beloved tomato, potato and pepper.

OK, it's clear that most of our food plants are non-native but I'll bet a few of those surprised you. Let's go to the landscape. How about our cool season lawn grasses such as Kentucky bluegrass, tall fescue, fine fescues and perennial ryegrass? Yep, non-native. When we enter the world of trees and shrubs the list of outstanding non-natives is too extensive to do justice to but here are a few I hope bring a smile to your face…Kousa dogwood, Koreanspice viburnum, Katsura tree and Dawn redwood. I love American elm but until they get one fully resistant to Dutch elm disease I'll take a Zelkova any day.

How about a redemption story? It is estimated that one-in-four trees in the Appalachian Mountains in about 1900 was American chestnut. Huge trees with strong, light wood and bumper crops of tasty nuts for people and wildlife were a few of its attributes. Few people can recall this giant of the woods. It was wiped out at the turn of the century by a fungus introduced from the Orient. (Yes, the fungus hitch-hiked in on a non-native chestnut). Now comes the redemption…plant breeders are on the verge of introducing a chestnut tree that has more than 90% of the American chestnut genes with the balance providing resistance to chestnut blight…from Chinese chestnut. When this new chestnut joins Canadian hemlock (ha, ha) Mountain laurel and common witch-hazel in our Pennsylvania woods it will be a great day.

Ok, what does all of this mean? Native plants should be appreciated, promoted, planted and never lost. However, I think it is short sighted and narrow minded to exclude the non-natives. Should we really create ordinances against non-natives, specify "native-only" in contracts or otherwise limit plant selection to natives? Penn State currently has a research project on Norway maple. Its intent is to determine if all cultivars of Norway maple have the capability of being invasive. The goal is to protect good Norway cultivars, if they exist, so that they can remain an option for those looking for a tough street tree or big shade.

I hate to use the word "global" but when it comes to plants, the word applies. People will continue to move plants around the world. Thousands of non-natives exist in Pennsylvania, alone. I love a good native but don't tell me I can't plant an apple tree (or yew) in my front yard. More on invasives in future issues.

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Horticultural Happenings

Garden Clubs - There are many different garden clubs all across Bucks County. Cooperative Extension compiles information on the Garden Clubs in the county. Most of the garden clubs offer monthly speakers on a variety of gardening topics. You can obtain a copy of the Garden Club list by calling the office at 215-345-3283. If you belong to a garden club and wish to have your club information added to the list, contact Susan Schneck at 215-345-3283.

PENN STATE WEB

Visit the improved Penn State Consumer Horticulture website at:
http://consumerhorticulture.psu.edu

Find Penn State Fact Sheets, answers to garden questions, and links to other Penn State and industry web sites. Search the Resource Library for information about various gardening topics. Learn about the Garden Forums , a day long gardening conferences in State College.

Penn State Cooperative Extension-Bucks County
Neshaminy Manor Center
1282 Almshouse Rd.
Doylestown, PA 18901

Phone: 215-345-3283
Fax: 215-343-1653
E-mail: bucksext@psu.edu

Scott Guiser, Extension Educator/Horticulture
and
Sue Schneck, Master Gardener Coordinator

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March / April 2006