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Common milkweed

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  • Native Plants,
  • Annuals, perennials and bulbs
Asclepias syriaca
Photo: Jardin botanique de Montréal (Stéphane Bailleul)

Onglets

Botany

Origin and description

The common milkweed is aptly named, it being the most common of our native milkweeds in Québec.

The scientific name of the species, syriaca, which refers to Syria, is puzzling, because this milkweed is exclusively North American. The name seems to have come about thanks to some confusion when the botanical description was done, in 1635. In French it’s often called “petits cochons” (little pigs) or “cochons de lait” (suckling pigs).

It constitutes a host plant and a nectar-producing plant for the monarch (Danaus plexippus plexippus). The monarch caterpillar feeds exclusively on milkweed leaves. It has broad thick leaves that are produced in opposing pairs on the stem. Its flowers, highly scented, range from pale pink to dull purple, and are arranged in an almost spherical inflorescence. The pod-like large fruit appear bloated when mature. They are lumpy, rough and covered with a wooly pubescence.

The common milkweed grows mostly in poor dry soil, often in environments that have been disturbed, such as roadsides and abandoned fields.

It reproduces easily through seeds, but also through the formation of underground stems (rhizomes) that extend horizontally and produce news plants where they emerge from the soil. It can therefore colonize a space with little trouble, and possibly become invasive. It often forms large colonies in fields and vacant lots from central to eastern Canada and the United States.

Height: 60 to 120 cm
Width: 40 to 60 cm
Flowering: soft pink to dull purple, fragrant, July to August
Attractions for wildlife: attracts butterflies and pollinators. Host plant and nectar source for the monarch butterfly.

See also the Québec's native milkweed.

Common name

Common milkweed

Latin name (genus)

Asclepias syriaca

French common name

Botanical family

  • Apocynaceae
Horticulture

Growing conditions

Exposure: sun
Soil type: dry or fresh, well drained

Observation: may become invasive in small gardens. Set aside a space for it where it can develop without harming other plants. If required, remove the fruit before they open and place a barrier in the soil to prevent propagation through rhizomes. Avoid planting this species close to farm land; in that situation, choose swamp milkweed (Asclepias incarnata) instead.

Hardiness

  • Zone 3

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