Specimen record
Common Milkweed
Asclepias syriaca
Description
The most widespread milkweed in eastern North America and the primary host plant for monarch butterfly caterpillars. Large spherical clusters of fragrant pink-purple flowers attract many pollinators in midsummer. All parts exude milky white latex when broken. The large warty seed pods split in autumn to release seeds attached to silky parachute fibers.
Identification tips
- 1Large spherical flower clusters (umbels) of pink-purple flowers
- 2Thick opposite leaves, oblong, with prominent pale midrib and milky sap
- 3Stout upright stems 1–1.5 m tall exuding white latex when broken
- 4Large warty green seed pods (follicles) 8–12 cm long
- 5Seeds with silky white 'parachutes' for wind dispersal in autumn
Specimen & preservation notes
Press flowering stems — blot the milky sap with paper towels immediately as it stains and creates sticky patches. Press a seed pod halved lengthwise to show seed arrangement. Collect silk-bearing seeds separately in an envelope. Allow extra drying time for the thick stems.
Collection calendar
| Wk | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov |
|---|---|---|---|---|---|---|---|---|
| 1 | ||||||||
| 2 | ||||||||
| 3 | ||||||||
| 4 |
Collection notes
Season check
Guide window is wider than observed records.
Flowering records: 494 iNaturalist observations, Massachusetts · Nearby: 1577 observations within 25 km