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Importance of Milkweed

Milkweed is crucial to the life-cycle of the monarch butterfly. Female monarchs search for milkweed to lay their eggs. Monarch larvae (caterpillars) will only feed on milkweeds in the Asclepias family. There are 108 species of milkweed in North America. Monarchs are only known to use 30 of them, but they may use any or all of them. Below is a list of milkweeds that Monarchs favor in Arizona. We hope to expand the list to the entire southwest. They are labeled whether they are more likely to grow in the low or high desert areas of the state.

Most species of milkweed contain cardiac glycosides. When the caterpillars consume the leaves, they become toxic to many predators. This protection continues when they become butterflies. Predators learn to avoid monarch larvae and butterflies because they taste bad or make them vomit. There is a wide variation in toxin strength in different kinds of milkweed.
Desert Milkweed (Asclepias subulata)

Want to grow your own milkweed from seeds? Click here

Tropical Milkweed (Asclepias curassavica) In The News

Table of contents

Arizona Milkweed (Asclepias angustifolia)
Antelope Horns or Spider Milkweed (Asclepsias asperula)
Tropical Milkweed Blood Flower (Asclepias curassavica)
Engelmann’s Milkweed (Asclepias engelmanniana)
Desert Milkweed (Asclepias erosa)
Rush (Desert) Milkweed (Asclepias subulata)
Narrowleaf Milkweed (Asclepsias fascicularis)
Broadleaf or Popcorn Milkweed (Asclepsias latifolia)
Pine-needle Milkweed (Asclepias linaria)
Mojave Milkweed (Asclepias nyctaginifolia)
Zizotes Milkweed (Asclepias oenotheroides)
Showy Milkweed (Asclepsias speciosa)
Horsetail Milkweed (Asclepias subverticillata)
Butterfly Weed (Asclepias tuberosa)

Butterfly Weed
(Asclepias tuberosa)

AZ mid & low elevations, CO, NM, southern UT
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Pine-needle Milkweed
(Asclepias linaria)

AZ low desert
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Desert Milkweed
(Asclepias erosa)

AZ CA NV low deserts
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Narrowleaf Milkweed
(Asclepias fascicularis)

Northern NV
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Mojave Milkweed
(Asclepias nyctaginifolia)

AZ high and low deserts
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Horsetail Milkweed
(Asclepias subverticillata)

AZ CO NM southern UT
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Arizona Milkweed
(Asclepias angustifolia)

AZ low Desert
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Engelmann’s Milkweed
(Asclepias engelmanniana)

AZ high deserts
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Zizotes Milkweed
(Asclepias oenotheroides)

AZ high and low deserts
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Rush or Desert Milkweed
(Asclepsias subulata)

AZ CA NV low deserts
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Antelope Horns or Spider Milkweed
(Asclepsias asperula)

AZ CO NM southern NV & UT
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Broadleaf or Popcorn Milkweed
(Asclepsias latifolia)

AZ NM southern UT
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Showy Milkweed
(Asclepsias speciosa)

AZ CO northern NV & UT

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