common milkweed (Asclepias syriaca)




















broadleaf milkweed
common milkweed
purple silkweed
silky swallowwort


Asclepias intermedia Vail
Asclepias kansana Vail
Asclepias syriaca L. var. kansana (Vail) Palmer & Steyermark


CONFIRMATION STATUS: Pending confirmation.


TAXONOMY: The currently accepted scientific name of common
milkweed is Asclepias syriaca L. Common milkweed is highly variable
in appearance. The color of the flowers may be attractive, or faded and
dingy-looking. This plant is often regarded as a weed to be destroyed,
but its flowers and foliage provide food to many kinds of insects. Com-

mon milkweed can be distinguished from other milkweeds by its prickly

follicles (seedpods) –other Asclepias spp. have follicles that are smooth,

or nearly so.


NATIVE STATUS: Native, United States and Canada.




Habit: Common milkweed is a native perennial plant 2-6' tall and un-



Leaves: The leaves are dull green, up to 8" long and 3½" wide, oblong

or oval in shape, and mostly oppositely arranged on the central stem.

There is a prominent central vein along the length of each leaf, and finer

side veins that radiate outward toward the smooth margins. When either

the central stem or leaves are torn, a milky sap oozes out that has variable

toxicity in the form of cardiac glycosides.


Flowers: Umbels of flowers, each about 3-4" across, emerge from the

axils of the upper leaves. These flowers are quite fragrant, with a scent

resembling violets or pansies, and they range in color from faded light

pink to reddish purple. Each flower is about ¼" across, with 5 reflexed

petals that occasionally entrap the legs of insects, and 5 raised hoods

with a horn arising in the middle.


Fruit/Seeds: The seedpods are 3-4" long, rather fat and covered with

soft prickles, and they split along one side when mature to release num-

erous seeds that are individually equipped with large white tufts of hair.

Dispersion of seed is by wind.


Roots: The root system has long creeping rhizomes, promoting the veg-

etative spread of this plant.


REGENERATION PROCESS: Common milkweed propogates itself
through seed dispersal and rhizome spread.


HABITAT TYPES: Habitats include moist to dry black soil prairies,
sand prairies, sand dunes along lake shores, thickets, woodland borders,
fields and pastures, abandoned fields, vacant lots, fence rows, and areas
along railroads and roadsides. This plant is a colonizer of disturbed areas
in both natural and developed habitats.


SITE CHARACTERISTICS: Common milkweed prefers full sun, rich
loamy soil, and mesic conditions, but this robust plant can tolerate a
variety of situations, including partial sun and a high clay or sand content
in the soil. Under ideal conditions, common milkweed can become 6' tall
and spread aggressively, but more typically it is about 3-4' tall. This plant
is very easy to grow once it becomes established.


SEASONAL DEVELOPMENT: The blooming period lasts about a
month from early to mid-summer.


GENERAL DISTRIBUTION: This plant grows throughout the Great
Plains ecoregion from southern Canada south to NE Oklahoma, NW

Georgia, and Texas, and east from North Carolina to Maine and into the

maritime provinces.




IMPORTANCE AND USES: The flowers are very popular with many
kinds of insects, especially long-tongued bees, wasps, flies, skippers, and
butterflies, which seek nectar. Other insect visitors include short-tongued
bees, various milkweed plant bugs, and moths, including Sphinx moths.
Among these, the larger butterflies, predatory wasps, and long-tongued
bees are more likely to remove the pollinia from the flowers. Some of the
smaller insects can have their legs entrapped by the flowers and die. Com-

mon milkweed doesn't produce fertile seeds without cross-pollination.
The caterpillars of Danaus plexippes (monarch butterfly) feed on the
foliage, as well as the caterpillars of a few moths, including Enchaetes

egle (milkweed tiger moth), Cycnia inopinatus (unexpected cycnia), and
Cycnia tenera (delicate cycnia). Less common insects feeding on this plant
include Neacoryphus bicrucis (seed bug sp.) and Gymnetron tetrum
(weevil sp.). Many of these insects are brightly colored – a warning to
potential predators of the toxicity that they acquired from feeding on
milkweed. Mammalian herbivores don't eat this plant because of the
bitterness of the leaves and their toxic properties (see following entry for
swamp milkweed for a more comprehensive discussion of importance and


People have used milkweed for fiber, food, and medicine all over the
United States and southern Canada. Milkweeds supply tough fibers for
making cords and ropes, and for weaving a coarse cloth. Milkweed stems
are collected after the stalks senesce in late fall-early winter. The dried
stalks are split open to release the fibers; milkweed fibers are sometimes
mixed with fibers of Indian hemp (Apocynum cannabinum). The bark is
removed and the fibers released by first rubbing between the hands and
then drawing the fibers over a hard surface. Twisting the fiber opposite
each other and twining them together forms the cord. Often this is accom-

plished by rolling the fibers on the thigh while twisting them together.

The young shoots, stems, flower buds, immature fruits, and roots of
butterfly milkweed were boiled and eaten as a vegetable by various
indigenous groups of eastern and mid-western America. The Meskwaki
steam the flower buds as a food source; they are nutritious but not
considered very flavorful.


The Cherokee drank an infusion of common milkweed root and virgin’s
bower (Clematis species) for backaches. The Cherokee, Iroquois, and
Rappahannock used the sap to remove warts, for ringworm, and for bee
stings. The Cherokee used the plant as a laxative, an antidote for gravel
and dropsy, and an infusion was given for mastitis. The Cherokee took an
infusion of the root for venereal diseases. The Chippewa made a cold
decoction of common milkweed root and added it to food to produce
postpartum milk flow. The Iroquois took an infusion of milkweed leaves
for stomach medicine. A compound decoction of plants was taken to
prevent hemorrhage after childbirth by the Iroquois. The Menominee
ate the buds or a decoction of the root for chest discomfort. The Ojibwa
used the root as a female remedy. The Potawatomi used the root for
unspecified ailments.


Common milkweed was used by the Meskwaki as a contraceptive. A
Mohawk anti-fertility concoction was prepared by boiling a fistful of dried,
pulverized milkweed and three jack-in-the-pulpit rhizomes in a pint of
water for 20 minutes. The infusion was drunk at the rate of one cup an
hour to induce temporary sterility.


Milkweed species as a group are known to contain cardiac glycosides that
are poisonous to humans and livestock, as well as other substances that
may account for their medicinal effect. Resinoids, glycosides, and a small
amount of alkaloids are present in all parts of the plant. Symptoms of
poisoning by the cardiac glycosides include dullness, weakness, bloating,
inability to stand or walk, high body temperature, rapid and weak pulse,
difficulty breathing, dilated pupils, spasms, and coma.


The cardiac glycoside in milkweed has also been useful as a chemical
defense for monarch butterflies (Danaus plexippus). Chemicals from the
milkweed plant make the monarch caterpillar's flesh distasteful to most
predators. Monarch butterflies are specific to milkweed plants; this is the
only type of plant on which the eggs are laid and the larvae will feed and
matures into a chrysalis. Eggs are laid on the underside of young, healthy
leaves. Monarch, queen, and viceroy butterflies are Müllerian mimics; all
are toxic, and have co-evolved similar warning patterns to avoid predation.

Milkweed species are attractive to many insect species, including the large
milkweed bug, common milkweed bug, red milkweed beetle, blue milk-

weed beetle, and bees. Accordingly, this is a wonderful horticultural plant

for landscaping to attract butterflies (particularly monarchs), whose num-

bers are declining and migratory routes changing due to lack of appropriate



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