Prairie Milkweed (Asclepias sullivantii)
Prairie Milkweed does look similar to Common Milkweed, however upon closer examination one will find it to be smaller in stature, have a bit more vertical orientation to its leaves and seed pods, and will find it to be mostly hairless. A somewhat rare native plant of mesic to mesic-wet Illinois prairies. 
 
Acronym: ASCSUL
Life-Cycle: Perennial
Bloom Color: Purple - Pink
Bloom Time: June - August
Typical Height: 36"
Light Preference: Full Sun
Soil Preference: Mesic
Root Structure: Rhizomes
Stratification: Cold & Moist for 30 Days
Seeds per Ounce: 4,500*
 
Other scientific names used for this species:
None
 
Other common names used for this species:
None
 
*Approximate, actual number of seeds may vary slightly by seed lot.