Asclepias syriaca

Asclepias incarnata

plant with a single stem, wide leaves plant with clump-forming stems, narrow leaves
inflorescence with pink, white and purple flowers inflorescence with white flowers (cultivar), wild species with pink flowers
corona filaments as long as corona corona filaments longer than corona
warty seed pod, never upright pod upright and smooth

Photos A. syriaca flowers: J. Schaminée-Sluis