Alien Invasive Weeds by Ranger Dan Small

Please don't try to remove alien invasive weeds without contacting the ranger first!

Volunteer by contacting Ranger Dan Small at 781-477-7123 or by e-mail at

What exactly are alien invasive weeds and are they a threat to Lynn Woods? Alien plants are those that are non-native or nonindigenous. Many alien plants are valuable agricultural crops, such as wheat and soybeans. Others are used as ornamentals, including tulips and many of our favorite shrubs. These plants are not able to compete outside of cultivation and pose little or no threat to natural ecosystems. The key word is invasive, as those plants that have a competitive edge over our native flora. Typically, these plants have some or all of the following characteristics: rapid growth and seed production, effective seed dispersal, rampant vegetative spread, and the ability to reproduce by fragmentation of the roots, tubers or stems.

The spread of invasives has been likened to a slow motion explosion. It is slow enough that you don't really notice it and suddenly it is too late. It has been estimated that nearly 4600 acres per day are being lost to colonization by invasive aliens and that they are the leading cause of extinction among endangered native plant species.

Unfortunately, we have invasive weed species in our woods. Most of them were accidentally introduced by the dumping of yard waste. Some, such as Burning Bush and Norway Maples, were purposely introduced as ornamentals. Invasive species that I have observed in Lynn Woods include Purple Loosestrife, Japanese Knotweed, Norway Maple, Burning Bush, Ailanthus Trees, Multifloral Rose, and Phragmities. Three of these (Burning Bush, Norway Maple and Multifloral Rose) do not appear to be widely established and their eradication should be relatively easy. Phragmities is present in all of the swampy areas of the park and eradication is impossible without destroying the wetlands. Healthy, undisturbed swamp ecosystems have been shown to have the ability to compete successfully with this species and hopefully this will be true in our woods. Purple Loosestrife is widely established in the three ponds, especially Birch Pond.

Eradication would be very time-consuming and would probably not be completely successful. Scientists are currently working on biological control methods for Loosestrife and the results are promising.

The last two on the list, Ailanthus Trees and Japanese Knotweed, are by far the most serious. Ailanthus trees will grow in any soil type, reach maturity rapidly, and are prolific seed producers (an estimated 350,000 per tree). They are ideally suited for the recolonization of the burned areas in Lynn Woods. Knotweed spreads by vegetative growth and has the ability to regenerate from tiny fragments of root and stem. It forms uniform colonies with a height of up to seven feet. These colonies completely shade the ground beneath killing all other plant life. If allowed to spread unchecked, it will eventually cover the banks of all of the ponds and colonize and destroy our wetlands.

We took the first steps toward eradicating these weeds last year, but we need more help. However, this is a case where misguided help can result in making the problem much worse. Extreme care needs to be taken when dealing with these plants to ensure that they aren't spread to uninfested areas.

See Also


Lynn Woods Wildflowers

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