Wild Parsnip
(Pastinaca sativa)
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Photo by Paul E. Berry |
DESCRIPTION: Wild parsnip is a member of the Umbelliferae
(parsnip) family. Rosettes grow close to the ground and bear leaves averaging
six inches in height. The plant has a long, thick taproot, which is edible.
Flowering plants produce a single, thick stem that contains hundreds of yellow
umbellate flowers. The lateral flowers often overtop the terminal flowers.
Depending on the habitat and growing conditions, individual flowering plants
range to over four feet in height. Leaves are alternate, pinnately
compound, branched, and have saw-toothed edges. Each leaf has 5-15 ovate to
oblong leaflets with variable toothed edges and deep lobes.
Wild parsnip can be
confused with prairie parsley (Polytaenia nuttallii), a native prairie species listed as
threatened in
DISTRIBUTION AND
HABITAT:
Wild parsnip is tolerant of a wide range of conditions, including dry, mesic, and wet-mesic prairies;
oak openings; and calcareous fens. It is shade-intolerant and prefers sunny
conditions.
LIFE HISTORY AND EFFECTS
OF INVASION: Wild parsnip can cause phytophotodermatitis
to the skin. If the plant juices come in contact with skin in the presence of
sunlight, a rash and/or blistering can occur, as well as skin discoloration that
may last several months.
This species reproduces
readily from seed. Seeds are fairly large and many are produced on one plant.
As a monocarpic perennial, wild parsnip spends one or
more years as a basal rosette. When conditions are favorable, it flowers,
produces seed, and dies. Look for the large, coarse, flower spikes and yellow
flowers from the first of June to the middle of July (although some plants may
continue flowering through late summer). Optimal growing conditions apparently
stimulate an increase in flowering. Apparently seeds take at least three weeks
from flowering to become viable.
Wild parsnip slowly
invades an area in waves following initial infestation. Once the population
builds, it spreads rapidly. This species is an aggressive, Eurasian weed that
frequently invades and modifies a variety of open habitats.
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Photo by Paul E. Berry |
CONTROLLING WILD PARSNIP
CAUTION: Care
should be taken to avoid skin contact with the juices of this plant. Proper
clothing (gloves and a long-sleeved shirt) must be worn to prevent the phytophotodermatitic effects.
Mechanical Control: The best way to control
wild parsnip is early detection and eradication. A very effective control
method is to cut the entire root just below ground level with a sharp shovel or
spade. Cutting below ground level prevents resprouting.
In some soil types in wet
conditions, the plants can be
pulled out of the ground by hand. All seeds must be removed from the site and
disposed of in a landfill or by burning.
If the population is too
large to hand-cut or pull, a power brush-cutter can be used just after peak
flowering and before the seeds set. Plants may resprout
when cut above the ground, and should be cut again a few weeks later to prevent
flowering. Cutting done after seed set will greatly reduce the likelihood that
the plants will be able to resprout and flower.
Plants cut at this time must all be gathered and removed from the site to
prevent mature seed from developing and falling to the ground. Another
effective way to eliminate reseeding is to hand-collect all seeds after they
have set. If control of flowering or seeding plants is carried out over several
years, the population will decrease as the seed bank is depleted.
Burning does not seem to
impact the plants themselves -- they quickly resprout.
However, in the darkened soil following a burn, these rosettes are easy to
recognize and can be controlled by hand-digging. Prescribed burning stimulates
increased growth in prairie species that may potentially decrease parsnip
populations through competition.
Chemical Control: Chemical controls are
effective, but should be used sparingly on quality natural areas. The best
method is to burn the site, then follow with spot application of 1-3% active
ingredient glyphosate. Immediately after a burn, wild
parsnip is one of the first plants to green. Glyphosate
can be spot applied to the basal rosette of the parsnip with little effect on
dormant species.
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More Information on the Web (links exit DNR) |
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There are chemicals in wild parsnip called psoralens (precisely, furocoumarins) that cause what dermatologists call "phyto-photo-dermatitis." That means an inflammation (itis) of the skin (derm) induced by a plant (phyto) with the help of sunlight (photo). When absorbed by skin, furocoumarins are energized by ultraviolet light (present during sunny and cloudy days) causing them to bind with nuclear DNA and cell membranes. This process destroys cells and skin tissue, though the reaction takes time to produce visible damage.
The chemical in wild parsnip may be a defense mechanism, just as healthy, green celery plants will produce higher levels of furocoumarins when they are under attack from pink-rot fungus.
In mild cases, affected skin reddens and feels sunburned. In more severe
cases, the skin reddens first, then blisters rise -- some are impressively
large -- and for a while the area feels like it has been scalded. Places where
skin is most sensitive (arms, legs, torso, face, neck) are most vulnerable.
Moisture from perspiration speeds the absorption of the psoralens.
Ouch! A run-in with wild parsnip can cause blisters and discoloration of
the skin.
© David J. Eagan
Blisters appear a day or two after sun exposure. Soon after blisters rupture and the skin begins to heal. One of wild parsnip's "signature" effects is a dark red or brownish discoloration of the skin in the area where the burn occurred. This hyper-pigmentation can persist in the skin for as long as two years.
Parsnip burns often appear as streaks and long spots. These reveal where a juicy leaf or stem drags across the skin, and is then exposed to the sun. Because of its surface resemblance to the effects of poison ivy, and because wild parsnip is so rarely accurately identified, it nearly always is diagnosed and treated as poison ivy. If you note the six clinical differences (see sidebar), however, you can readily tell them apart.
Treating a parsnip burn
If you get a parsnip burn, relieving the symptoms comes first. The affected area can be covered with a cool, wet cloth. If blisters are present, try to keep them from rupturing for as long as possible. The skin of a blister is "nature's bandage," as one doctor put it, and it keeps the skin below protected, moist and clean while healing occurs. When blisters pop, try to leave the skin "bandage" in place. To avoid infection, keep the area clean and apply an antibiotic cream.
Adding Domeboro powder to cool cloth compresses can help dry weeping blisters. Some doctors recommend a topical or systemic cortisone-steroid for extreme discomfort. For serious cases with extensive blistering, consult a physician.
Avoiding exposure, of course, is the wisest tactic. By learning to recognize the plant in different seasons and in different stages of growth, you can steer clear of it, or protect yourself by wearing gloves, long pants and long-sleeve shirts. Some people pull up the wild parnsips in the evening, when exposure to sunlight is minimal. If you do get the plant juice on your skin, the sooner you thoroughly wash the area, the less you will be affected.
Wild Parsnip
(Pastinaca sativa)
Habitat: wastelands, wet sites, roadsides and pastures, undisturbed ground
Life cycle: biennial
First Year Growth Habit: Rosette of basal leaves. Large, three-lobed leaves resemble celery.
Second Year Growth Habit: 2-5 feet, branched, flowering plant
Leaves: Alternate, pinnately compound with coarse saw-tooth edges; deeply lobed and not hairy. Up to 18 inches long.
Stem: hairy and grooved
Inflorescence: May-August (second year). Small flowers with five yellow or white petals borne in terminal umbels, 2-6 inches across.
Root: fleshy taproot
Similar plants: Second-year plant is somewhat similar to poison hemlock (Conium maculatum). The leaves of poison hemlock are usually more finely divided and its stems are hollow and purplish.
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The problem
is.... wild parsnip produces huge amounts of seed, allowing it to persist
and spread. NOTE: Although wild parsnip has edible roots, it should be
avoided because of the possibility of confusion with poison hemlock.
Additionally, the leaves of wild parsnip cause a painful and potentially
serious rash on some people. Skin sensitivity is greatest at flowering time. Wild parsnip in its first year
of growth. |
Usually wild parsnip has yellow
umbels, as in this picture, but it may |
The leaves of wild parsnip are not
as finely divided as poison hemlock,
however, and its stem is ridged and green.
http://dnr.state.il.us/lands/education/ExoticSpecies/Wildparsnip.htm