Download 2/29/2016 - Invasive Species of Illinois

Invasive Species of Illinois
By Lauren Marks
Restoration Technician
Tis the season for the Byron Forest Preserve District’s restoration crew to fuel up
for the cooler seasons. This team does not hibernate! The crew will be focusing on
removing some of the invasive species of Illinois from some of our preserves. Some of
these species include Amur Honeysuckle (Lonicera maackii), Common Buckthorn
(Rhamnus cathartica), and Black Locust (Robinia pseudoacacia).
Amur Honeysuckle (Lonicera
maackii) was introduced from Asia
as an ornamental plant.
Unfortunately, it can invade
cultivated areas and areas that have
the most desirable native plants (high
quality natural areas). It is difficult to
eradicate and it spreads aggressively without management in our natural areas. This
species loves to grow in full sun to light shade and in moist to dry-mesic conditions with
soil that contains loam (a mixture of sand and clay). It can be found in woodlands and
savannas. Amur Honeysuckle’s bark has flat scaly ridges and narrow grooves. Its leaves
are green on the top and a pale green below, which grow up to 3 ½ inches long. In the
late spring, this Honeysuckle produces white flowers that last up to 3 weeks. Berries that
are a shiny red color and are juicy later replace the flowers. Amur Honeysuckle reseeds
itself, causing it to displace native species and destroy the unadulterated landscape.
Common Buckthorn (Rhamnus
cathartica) is native to Europe and
western and northern Asia. It was
introduced to the United States as an
ornamental tree. Once Common
Buckthorn is established in our natural
environments, it replaces the native woody understories of the woodlands. It creates a
thicket, making it very difficult for our native species to survive in its shadow. Common
Buckthorn is difficult to eradicate from our natural environments because it sprouts
vigorously and repeatedly from root collar following cutting and burning. Common
Buckthorn is found in urban and suburban environments, roadsides, median strips, and
forest understories. It is a small tree that grows up to 25 feet tall. It has opposite green
leaves that grow up to 2 ½ inches long. Its bark is thin, dark brown to black, shiny,
smooth, and becoming rough and scaly. This species likes to grow in full sun, but it can
tolerate drought, poor soil, and wind. It is moderately fast growing and is short lived. In
the late spring, you can see its bell-shaped flowers that are a yellowish green color. Its
black round fruits (drupe) grow from August to September. These fruits are nauseating
and poisonous to humans. Birds disperse the seeds from the fruit.
Black Locust (Robinia pseudoacacia) is native to southeastern United States and
can be seen along the roadsides in Illinois. It grows dense thickets and sprouts readily
from roots, especially after cutting. This medium-sized tree grows up to 80 feet tall. Its
dark brown bark is deeply furrowed,
brittle, and thick. This Locust has
extremely hard wood, which is used for
fence posts, lumber, tool handles, boxes,
and crates. It also has paired red thorns
that are found at the leaf base. Its alternate
compound leaves grow up to 10 inches long with 7 to 9 leaflets on each leaf that are a
bluish-green. From May to June, you can see its white showy flowers that grow in a
drooping cluster. These flowers are very fragrant, which smell like honey and/or vanilla.
In late autumn, Black Locust grows smooth dark brown pods that are 7 to 10 cm long and
stay on the tree all winter. It grows better in lighter-textured soils, such as sand, and
thrives on limestone-derived soils. This Locust is shade tolerant; fast growing, and short
lived. Even though it is beautiful, the Black Locust is deadly to native species.
Amur Honeysuckle, Common Buckthorn, and Black Locust are a few of the
different invasive species that our restoration crew will be working on removing during
the upcoming seasons. Our restoration staff will be cutting and removing the invasive
species from all of our natural areas. Then we will herbicide spray the stumps that are
left, in our effort to control the invasive species and to help prevent re-sprouting. By
doing this, the crew gives our native species a better chance to thrive and to reproduce on
our preserves. Please remember these species are similar to an international spy, they can
be incredibly beautiful but extremely deadly.