Green Milkweed

Asclepias ovalifolia

Hosts 1 caterpillarSpecialist hostPollinator plant

Growing it

When	Flowers June to July; fruits August to September
Type	wildflower
Sun	Full sun
Water	Low
Soil	pH 6–7.5
Hardiness	zone 3–6
Mature height	0.5 m
Mature spread	0.75 m
Spacing	0.5 m
Years to maturity	3
Bloom	Jun–Jul
Flower colour	Green checked against its common name
In bloom	June July
Fruit	Aug–Sep
Native to	AB, SK

elliptic leaves about 15 cm long in opposite pairs

Where it has been recorded

BothSpecimensObservations

86 squares of about 28 km, each holding at least one record. A square is not a claim that the plant grows throughout it, and an unshaded square is unrecorded rather than empty. Darker squares hold more records, which follows roads and towns as much as it follows the plant. 28 herbarium specimens and 164 field observations this project may redraw. A filled dot is a pressed sheet somebody can re-examine; a hollow ring is a photograph identified by community agreement. Where the dots are dense is where people have looked, not where the plant is commonest, and empty ground is unsurveyed rather than unoccupied. How this map is made.

Which ecoregions the records fall in

Aspen Parkland central AB / SK: 215 records, high confidence
Boreal Transition central AB / SK: 36 records, high confidence
Moist Mixed Grassland south AB / SK: 31 records, high confidence
Mid-Boreal Uplands central AB / SK: 14 records, medium confidence
Peace Lowland north AB: 8 records, medium confidence

These are counts of records collected somewhere in the region, which is the resolution of the evidence: the map above shows where inside it. A region with 3 records is not the same claim as one with three hundred, so the count travels with the region. A region missing from this list means nobody has recorded it there, which is not the same as the plant being absent. Records within 900 m of a border count for neither side, because the border is not drawn finely enough to say which one they are on. Source: GBIF occurrence search + PRESERVED_SPECIMEN pass, retrieved 2026-08-24. Boundaries digitised from the National Ecological Framework for Canada v2.2 (Ecological Stratification Working Group 1995), simplified to about 900 m for display: an outline is accurate to roughly a kilometre, not to the metre. How these counts are made.

See every observation, live and current, on GBIF or iNaturalist.

Documented animals

3 documented relationships, 1 with a specialist that has no alternative.

nectar for

Hummingbird Clearwing Moth Specimen records from iNaturalist.org
Monarch Specimen records from iNaturalist.org

caterpillar host for

Monarch ★Acorn & Sheldon 2006

Also worth knowing

Safety

High toxicity to pets; High toxicity to people

Edible parts

Young shoots, flower buds, young seed pods (cooked only)

Buying it

About $8–$16 per plant (estimate), usually from a native-plant nursery. Estimate (herb default); AB retail as of 2026

Where these numbers came from

Flower detail: not verified, a genus-level estimate