Come out for a CITO event to remove an invasive plant. We are
going to join forces with The Nature Center at Friendship Woods to remove
an invasive specie, Garlic Mustard. Buckets will be provided to
collect the plants as well as on how to identify the Garlic Mustard
plant. Bring your own gloves, knee pads, etc. as you see fit. If
you have one of those dandelion picker, that would be a great tool
to bring as the Garlic Mustard has a tap root. Garlic Mustard is a
ground hugging biennial that will be green at this time of the
year.
When
Saturday April 10, 2010
From 2:00 - 3:30 pm
Where
The Nature Center at Friendship Woods
30300 Hales
Madison Heights, MI 48071
(248) 585-0100
And now for some information about this plant.
Background
Garlic Mustard was first recorded in the United States about 1868,
from Long Island, New York. It was likely introduced by settlers
for food or medicinal purposes.
Description
Garlic Mustard [Alliaria petiolata] is a cool season
biennial herb with stalked, triangular to heart-shaped, coarsely
toothed leaves that give off an odor of garlic when crushed.
First-year plants appear as a rosette of green leaves close to the
ground. Rosettes remain green through the winter and develop into
mature flowering plants the following spring. Flowering plants of
Garlic Mustard reach from 2 to 3 1/2 feet in height and produce
button like clusters of small white flowers, each with four petals
in the shape of a cross.
Garlic Mustard Biology and Life Cycle
It most often grows in the forest understory or along forest edges
but is also able to invade undisturbed forest habitats. It
tolerates low light levels and is adapted to take advantage of
disturbed habitats such as trails, roadsides and areas where trees
have been removed. Garlic Mustard has no significant natural
enemies in North America, although a diverse community of
herbivores feed on it in its native range in Europe. Populations of
Garlic Mustard can spread rapidly. In a study of high quality
woodlots, i.e. typically old growth or undisturbed forest habitat
in Illinois, Garlic Mustard advanced an average of about 20 feet
per year, expanding as much as 120 feet in one year. When
established, Garlic Mustard becomes a permanent member of the
community, often dominating the ground layer habitat over extensive
areas.
Garlic Mustard appears to alter habitat quality for several
species of salamanders and mollusks through changes in forest
litter layer depth and composition. Insect communities are also
impacted by the presence of Garlic Mustard. The native woodland
butterfly Pieris napi oleraceae, utilizes the native toothworts
Cardamine concatenata [Dentaria laciniata] and C. [Dentaria]
diphylla, which produce the chemical attractant sinigrin. This
compound is also present in Garlic Mustard. Because Garlic Mustard
grows taller than the native hosts, in mixed stands the butterflies
can mistakenly lay their eggs on Garlic Mustard where their larvae
are unable to develop. The impacts of Garlic Mustard on vertebrates
are largely unknown, however, ground foraging birds, amphibians and
reptiles may be impacted by changes in habitat quality.
First Year Plants
Garlic Mustard reproduces only by seed. Most seeds germinate within
the first or second year after being produced but can remain viable
in the soil seed bank for up to five years. Seeds require prolonged
exposure to cold before they can germinate. Seeds germinate in the
spring and form low growing rosettes of dark purple to green,
kidney-shaped leaves with scalloped edges. Leaves grow on stalks
that are a half to 2 inches long called petioles. Young leaves
smell distinctly of garlic or onion when crushed, although the odor
becomes less intense as plants grow older. Seedling density in
infested areas can reach nearly 17,000 per square yard in the fall,
although overwintering mortality is high and rosette density in the
spring averages 25 to 70 per square yard, but occasionally reaches
as high as 375 per square yard.
Second Year Plants
Leaves on second year plants are roughly triangular and sharply
toothed, a little over one to three inches wide and long becoming
gradually smaller towards the top of the stem. As with first year
plants, young leaves smell distinctly of garlic or onion when
crushed, although the odor becomes less intense as plants grow
older.
Shoot elongation from the rosette occurs in the spring, with the
plant growing as rapidly as three-quarters of an inch per day.
Flowers are continuously produced at the top of the long stalk.
Flowering occurs in late April through June in southern Michigan.
Flowers are white with four petals that form a cross. The flower is
similar to others in the Mustard family with six stamens: two long
and four short. Petals taper sharply toward the base of the
flower.
Individual plants produce from 350 to 7,900 seeds and grow to 3
to 4 feet in height. Seeds are produced inside slender pods called
siliques. Each silique is approximately 1/16 of an inch wide and
one to two and a half inches long and forms off the stem just below
the flowers.
Siliques grow on short, rugged stalks and radiate out from the
stem. Wind dispersal is limited and most seeds fall within a few
yards of the plant. Dense stands can produce about 12,500 seeds per
square yard each year. Humans transport seed on boots, clothing,
hair, by mowing, in automobiles and trains. Birds, rodents and
whitetail deer are likely seed dispersers in woodland habitats.
Garlic Mustard seeds can remain viable in the soil seed bank for up
to five years.
Ecological Threat
Garlic Mustard poses a severe threat to native plants and animals
in forest communities in much of the eastern and midwestern U.S.
Many native widlflowers that complete their life cycles in the
springtime (e.g., spring beauty, wild ginger, bloodroot, Dutchman's
breeches, hepatica, toothworts, and trilliums) occur in the same
habitat as Garlic Mustard. Once introduced to an area, Garlic
Mustard out competes native plants by aggressively monopolizing
light, moisture, nutrients, soil and space. Wildlife species that
depend on these early plants for their foliage, pollen, nectar,
fruits, seeds and roots, are deprived of these essential food
sources when Garlic Mustard replaces them. Humans are also deprived
of the vibrant display of beautiful spring wildflowers.
In West Virginia, the white butterfly (Pieris virginiensis) lays
it's eggs on a plant of spring wildflowers known as "toothworts"
(Dentaria), also in the Mustard family. These plants are the
primary food source for the caterpillar stage of this butterfly.
Invasions of Garlic Mustard are causing local extirpations of the
toothworts, and chemicals in Garlic Mustard appear to be toxic to
the eggs of the butterfly, as evidenced by their failure to hatch
when laid on Garlic Mustard plants.
