Wildflowers of Toronto's High Park​​

Milkweeds

Genus: ​Asclepias​​
Family: Dogbane
Native to Ontario
Perennial

Milkweed leaves are an essential food for the caterpillars of monarch (and some other) butterflies.
A substance ingested makes both the caterpillar and subsequent butterfly poisonous, so that birds avoid eating them. 

Milkweed flowers are pollinated by bees, butterflies and moths.  When an insect's foot enters a slit between the nectar-filled points in the flower, tiny pollen-coated "pollinia" (which look like saddlebags) attach themselves to the insect's leg.  


​Milkweeds have unusual flowers. The petal-like corolla lobes, known as "horns" are bent backwards exposing the corona - 5 erect "hoods," each containing a stamen, which form a crown enclosing 2 pistils. 

Milkweed, common
​A. syriaca

Habitat: Disturbed areas
Blooms: June to August

Height: up to 1.8 m

​Flower: 1-1.5 cm arranged in dense globular clusters. Colour varies from greenish to yellowish-brown to pinkish-purple. Has a strong sweet fragrance.

​Leaves and stem exude a milky sap. 

​Fruit: 8-12 cm horn-shaped pods containing many seeds with fluffy appendages, dispersed by wind. 


Milkweed, swamp
​A. incarnata

Habitat: Wet places, shorelines
Blooms: June to August

Height: up to 1.5 m

​Flower:  5-7 mm in a flat-topped umbel.
​Deep pink or magenta.

Milkweed, whorled
​A. verticillata

Habitat: Dry fields or woodland
Blooms: June to September

​Flower:  2 mm, green-white in cluster.

Leaves in whorls.

Milkweed, butterfly  or  Butterflyweed
​A. tuberosa

Habitat: Tall grass prairies and savannas 
Blooms: June to August

​Flower:  7-10 mm in flat-topped umbel.

​Fruit: Narrow erect seed-pods.

Unlike other milkweeds, its sap is clear.

Milkweed, purple

​A. purpurascens

Habitat: Dry fields
Blooms: Summer

​This species has been planted in
High Park Nature's OURSpace.