SafePlants

Asclepias curassavica: A Multifaceted Milkweed

Asclepias curassavica, often celebrated as one of the most visually striking milkweeds, goes by a plethora of common names, including Mexican Butterfly Weed (Orange), Scarlet Milkweed, Tropical Milkweed, Blood Flower, Indian Root, Swallow-wort, Red Cottonweed, and Silkweed. It is also sometimes referred to as simply Mexican Milkweed.

Taxonomy and Nomenclature

• Scientific Name: Asclepias curassavica
• Family: Asclepiadaceae (part of the Milkweed family)
• Synonyms: The text also mentions several other species within the *Cynanchum* genus that were formerly included in the Asclepiadaceae family, and some of the same common names overlap.

Considerations for Pets

• This plant is referred to as "swallow-wort".
• The text mentions that plants "can be poisonous to livestock".
• The name "Indian Root" is used to describe it.

Considerations for Children

• This plant is referred to as "swallow-wort".
• The name "Indian Root" is used to describe it.

Distribution and Habitat

This species thrives in warmer climates, where it can naturalize and even become weedy. It is found natively across the desert southwest of the United States, extending into western Nebraska, Arkansas, and Mexico. The plant also has a presence in Mexico, Central America, South America, and Africa.

Ecological Role

• Monarch Butterfly Host: While valued for attracting monarch butterflies, in certain regions, particularly in the US where migratory monarchs are found, planting this species is discouraged. Other species like black swallow-wort (Cynanchum louiseae) are noted for being deadly host plants for monarch larvae and competing with native milkweeds.
• Invasive Potential: The text identifies *Asclepias curassavica* as a naturalized weed in warmer climates, suggesting its potential to spread aggressively. Other *Cynanchum* species can form tangled masses, suppressing other vegetation by blocking sunlight.

Cynanchum Species: Swallow-Worts

Several Cynanchum species are mentioned, often sharing the common name "swallow-wort." These include:

• Cynanchum ligulatum (Benth.) Woodson
• Cynanchum louiseae (Black Swallow-wort, Louise's Swallow-wort, Black Dog-strangling Vine)
• Cynanchum maccartii Shinners (Maccart's Swallow-wort)
• Cynanchum sinaloense (Brandeg.) Woods.
• Cynanchum barbigerum (Bearded Swallow-wort)

Ecological Role

• Invasive Potential: Black swallow-wort (*Cynanchum louiseae*) is specifically highlighted as an invasive species that threatens monarch butterflies and grows over other vegetation, blocking light.