Tropical Milkweed (Asclepias curassavica) is now ...Tropical milkweed (Asclepias curassavica) is a fast-growing, non-native perennial popular in Florida for attracting monarch butterflies, reaching 2–4 feet in height with red, orange, and yellow flowers. While it thrives in full sun, it is discouraged by conservationists because it spreads aggressively, can become invasive, and harbors high levels of the harmful protozoan parasite OE (Ophryocystis elektroscirrha) due to its year-round growth.