Common Milkweed

Asclepias syriaca

Description & Overview

Common Milkweed is, well, common throughout the entire state of Wisconsin. Large, thick leaves grow along an upright stem, topped with clusters of fragrant, pink blooms in early summer. It is easily identifiable in that when a stem or leaf is torn the plant will exude a characteristic white latex sap.

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Core Characteristics

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Suggested Uses:

Common Milkweed does not discriminate when it comes to site conditions. Clay, sandy, or rocky soils? Not a problem. Disturbed sites, railways, roadsides, ditches, abandoned pastures, forest edges, and fields are its bread and butter.

Naturalizing: It is best to let Common Milkweed do what it wants to do, which is spread. This is a perfect recipe for populating old empty lots and overgrown areas recently cleared of weeds. Site in a location where it is allowed to spread and it will not disappoint.

Native/pollinator garden: The charismatic and endangered Monarch Butterfly depends on this plant for its survival. The large leaves can sustain more Monarchs! Bees galore also rely on this plant.

Wildlife Value:

Common Milkweed is a host plant to many insects. In fact, more than 450 insects are known to feed on some parts of the plant. A toxic compound in the Milkweed imparts an orange-red coloring to the insects that feed on it and also serves as a warning to birds that, in turn, feed on those insects, signaling that they may be toxic. This offers the insects that use Milkweed as a host plant not only shelter and sustenance but also a form of defense.

The most infamous of these insects is of course the Monarch Butterfly (Danaus plexippus), but others of mention include the Milkweed Tussock Moth (Euchaetes egle), Common Milkweed Bug (Lygaeus kalmii), Large Milkweed Bug (Oncopeltus fasciatus), Swamp Milkweed Leaf Beetle (Labidomera clivicollis), and the Unexpected Cycnia (Cycnia inopinatus). Interestingly, Monarchs prefer young shoots for their larvae, while the Milkweed Tussock Moth prefers older, tougher foliage. This reduces competition on the same plant, allowing the two species to cohabitate with the plant.

Along those same lines, the Common Milkweed Bug (Lygaeus kalmii) feeds primarily on the seeds, but can also feed on Monarch caterpillars. Red Milkweed Beetles prefer Common Milkweed over other Milkweed species, overwintering in their roots.

Milkweed pollination could take up an entire article on its own. Briefly, the flowers have evolved a rather complicated pollination mechanism that is reliant on heavy-bodied insects such as bumblebees and butterflies. Buckle up nerds because it is about to get a little complicated but this information adds to the wonder that is plants and our natural world! So here it goes: The insect is tempted to drink the milkweed’s fragrant nectar from a slippery structure on the milkweed flower called a hood. The flower is structured so that the insect’s leg will slip down the hood and into a crack, which happens to hold the pollen sac. Larger insects are strong enough to pull their leg, along with the pollen sac out of this crack to bring it to the next flower, at which point the pollinator’s leg slips into the crack and drops off the pollen sac while pulling its foot back out, effectively completing pollination. Interestingly, smaller insects such as honeybees may be large enough to get their foot stuck, but too small to get it out and can, in fact, get stuck in the flower, losing a limb while trying to escape, or dying on-site. One might wonder what makes it worthwhile to risk literal life and limb to visit a Milkweed flower but it is safe to assume it is likely due to the high volume of nectar they produce. It is also worth asking if the decline in Milkweed is not just due to dwindling habitat but also due to the decline of bumblebees and others who are the only ones capable of pollinating it!

Many insects visit the flowers for their nectar and pollen including Edward’s Hairstreak (Satyrium edwardsii), Coral Hairstreak (Satyrium titus), Regal Fritillary (Speyeria idalia), Red Admiral (Vanessa atalanta), Painted Lady (Vanessa cardui), Mourning Cloak (Nymphalis antiopa), Common Buckeye (Junonia coenia), Eastern Tiger Swallowtail (Papilio glaucus), Eight-spotted Forester Moth (Alypia octomaculata), Hummingbird Clearwing Moth (Hemaris thysbe), Great Spangled Fritillary (Speyeria cybele), and Sulphur butterflies (Colias spp.).

Western honeybees (Apis mellifera), Leafcutter bees (Megachile spp.), Green Sweat bees (Augochlora spp.), Small Carpenter bees (Ceratina spp.), Small Resin bees (Heriades spp.), Sweat bees (Lasioglossum spp.), Thread-waisted wasps (Prionyx spp.), Cuckoo bees (Coelioxys spp.), Soldier bees (Chauliognathus spp.), Banded Long-horned beetles (Typocerus spp.), Long-horned beetles (Euderces spp., Trigonarthris spp.), Bumble bees (Bombus spp.) and Yellow-faced bees (Hyaleus spp.) are all visitors of Common Milkweed, the smaller species literally risking their lives for some of that sweet nectar!

American Goldfinches use milkweed fiber for nesting material.

Maintenance Tips:

Milkweed will readily reseed and spread if left unchecked. If space is a concern, the seedpods can be cut off prior to opening. Truth be told, Common Milkweed can be aggressive. It is, however, not a weed. If spread is not something you want to deal with, there are other Milkweed species that don’t spread as quickly, such as Purple Milkweed, which looks almost identical except that it has more pointed tips, netted veins, and slightly darker purple/pink flowers.

Pests/Problems:

Black Walnut Tolerant: Yes
Deer Resistant: Yes
Rabbit Resistant: Yes

Milkweeds are prone to aphids. This is normal and not a cause for worry. In fact, quite a few insects eat the leaves. A reality check may be helpful here: as a native plant, this is what we planted them to do!

This species has a long taproot, making transplanting difficult.

Leaf Lore:

This species can be differentiated from other milkweeds by its spiky seed pod, among other characteristics.

Many Indigenous peoples used Milkweed as food and for medicinal purposes. Young shoots, stems, buds, and roots were boiled and eaten. The Meskwaki steamed the flower buds for eating and used the plant as a contraceptive. The Ojibwa ate the young shoots and flower buds and used the fresh flower and shoot tips to thicken meat soups. The Chippewa tribe ate milkweed to increase their appetite, used plants to aid in milk production, and applied the roots to whistles to call deer. The ‘milk’ of milkweed was used as a treatment for warts, bee stings, and cuts by the Iroquois.

May Indigenous peoples used the fiber inside the seedpod to make cords and ropes.

Some other interesting uses:

• In WWII, because the material used to fill life jackets was in such short supply, the floss of milkweed was used as a substitute.
• Milkweed is grown as a hypoallergenic filling for pillows and for insulation in winter coats.
• The silky strands are used in thermal and acoustic insulation and oil absorbents.

Companion Plants:

Create a beautiful, functional butterfly garden by planting Common Milkweed alongside:

• Ironweed (Vernonia fasciculata)
• Smooth Aster (Symphyotrichum laeve)
• Golden Alexanders (Zizia aurea)
• Stiff Goldenrod (Solidago rigida)
• American Plum (Prunus americana)
• Black Willow (Salix nigra)
• Spotted Bee Balm (Monarda punctata)
• White Turtlehead (Chelone glabra)
• White Wild Indigo (Baptisia alba)
• Quaking Aspen (Populus tremuloides)
• Pale Purple Coneflower (Echinacea pallida)
• Sand Coreopsis (Coreopsis lanceolata)

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