It’s the only food the larva can eat. The
caterpillars absorb toxins from milkweed plants into their bodies.
The toxins will sicken birds, lizards, and mammals, but predators
like wasps and spiders are immune to them.
At the Dana-Thomas House Cottage Butterfly Garden seven varieties of
native milkweed (Asclepias) were planted in 2014. In 2019, only
Common Milkweed remained. Wrong site location or crowding may have
caused the other milkweed plants to die out. There are twenty-four
species of milkweed native to a variety of habitats in Illinois.
Here is information about seven species native to Illinois.
Asclepias syriaca, Common Milkweed, is a robust plant growing
up to 5 feet tall. It is found in old fields, pastures, degraded
prairie, and along roadsides. The flowers are in large rounded
clusters at the tops of the stems and in the upper leaf axils. Each
dark pink flower is about .25 inches across. The plant blooms May
through August. The fruit pods are up to 4 inches long. Give common
milkweed plenty of space to grow as it aggressively spreads by
underground rhizomes.
Asclepias sullivantii, Prairie Milkweed, is found in moist
prairies in the northern part of the state. It grows about 3 feet
tall and produces dark pink flowers. There are from one to several
flower clusters near the top of each stem, blooming in June and
July.
Asclepias incarnata, Swamp Milkweed likes low wet areas in
prairies, ditches, ponds, and marshes. It can grow up to 5 feet
tall. It has narrower leaves than Common and Prairie Milkweed. The
dark pink blooms appear June through August. [to top of second
column] |
Asclepias purpurascens, Purple
Milkweed, is found in prairies, open woods, and thickets throughout the state.
It produces purple flowers from May through July. The flowers are in large
rounded clusters at the top of the stem.
Asclepias verticillata, Whorled Milkweed is a slender single-stemmed
plant with whorled leaves that grows to 18 inches tall. The white to pink
flowers appear in April and May. It grows in dry or rocky open woods in the
southern part of the state.
Asclepias exaltata, Poke Milkweed, got its name because the leaves
resemble those of the pokeweed plant. It is an uncommon plant found in open
woodlands, rich mesic woods, and sandy woodlands and is considered an indicator
of good quality woodland habitat. This upright plant grows to 5 feet tall. It
blooms in June, producing loose clusters of drooping, starry, white flowers with
swept-back green sepals. The flowers may have a tinge of lavender.
Asclepias tuberosa, Butterfly Weed, is a milkweed that can be found at
many garden centers. It grows to 2.5 feet tall and has flowers that range from
orange to pale yellow. The leaves are narrow. It grows in prairies, dry open
woods, savannas, old fields, and roadsides.
[Source: Jennifer Fishburn,
University of Illinois Extension, Horticulture Educator]
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