Butterfly Milkweed vs Tropical Milkweed

These two plants are sometimes confused due to the similar color of their flowers and similar seedpod shape. They are easily distinguished by a close look at the flowers, leaves, or seedpod texture. Tropical milkweed is widely planted in gardens, but in the wild it is restricted to the southernmost parts of North America. Outside of gardens, butterfly weed occurs in dry habitats whereas tropical milkweed is more likely in wetter habitats.

Butterfly Milkweed (Asclepias tuberosa)	Tropical Milkweed (Asclepias curassavica)
Butterfly Milkweed (Asclepias tuberosa) An orange-flowering perennial of dry, sunny areas, favoring sites with acidic soils, especially on sandy or rocky soils.	Tropical Milkweed (Asclepias curassavica) A short-lived, showy milkweed native to the tropical Americas, and widely planted in gardens; in North America it can harm monarch butterfly populations, and has some potential to become invasive.
Butterfly Milkweed (Asclepias tuberosa) Flowers usually orange, occasionally yellow or reddish, but consistent in color on each plant, with little contrast between petals and hoods. Photo © Will Kuhn, CC BY 4.0.	Tropical Milkweed (Asclepias curassavica) Flowers may appear orange at a distance, but upon close examination, petals are deep red contrasting with bright yellow hoods. An exception is an uncommon all-yellow cultivar. Photo © Miguel Angel Ramírez Guillermo, CC BY 4.0.
Butterfly Milkweed (Asclepias tuberosa) Smaller (both narrower and shorter) leaves, thick and leathery in texture on mature plants. Photo © Esben Kjaer, CC BY 4.0.	Tropical Milkweed (Asclepias curassavica) Leaves larger, often both broader and longer, and with a thinner, more delicate texture. Photo © Valerie Anderson, CC BY 4.0.
Butterfly Milkweed (Asclepias tuberosa) Outside of gardens, typically found in dry habitats, often ones with sandy soil. Photo © Marilynn Miller, CC BY 4.0.	Tropical Milkweed (Asclepias curassavica) Outside of gardens, typically found near water or in moist habitats. Photo © Grete Pasch, CC BY 4.0.
Butterfly Milkweed (Asclepias tuberosa) Seedpods pubescent, soft to the touch and pubescence usually visible in photos. Photo © Sandy Wolkenberg, CC BY 4.0.	Tropical Milkweed (Asclepias curassavica) Seedpods smooth, or at least less conspicuously pubescent. Photo © Francisco Farriols Sarabia, CC BY 4.0.

References & External Resources

These short lists show only links helpful for ID. For a complete list of references and resources also covering other aspects of ecology, visit the links section of the full article on each plant, which is the first entry here.