Probably THE MOST popular topic in Florida Native Gardening revolves around Tropical Milkweed and identifying it against native milkweeds. Not only has Florida Native Gardening exploded with interest in recent years, but so has butterfly gardening. Milkweeds fall into both of these categories as there are several native milkweeds and they are the host plant to the most popular butterfly - The Monarch Butterfly. However, there is also a non-native milkweed that has become available basically everywhere. Tropical Milkweed or Asclepias curassavica has flooded nurseries advertising it as an easy to grow butterfly plant. Some growers even purposely label it as Butterfly Milkweed which confuses people even more on if it is one of the natives.

This post is not going to discuss the importance of NOT buying and planting Tropical Milkweed. If you would like more information on that topic Click Here for multiple articles on the topic. Click Here for my explanation of why I got rid of all the Tropical Milkweed in our garden.

Here's how to tell the difference between Tropical Milkweed and the native look-alikes. First start with analyzing the flowers. If they are red and yellow you have Tropical Milkweed. If the flowers are orange, you need to move on to analyzing the leaves, plant height, and seed pods. Break open a leaf first. If you see milky sapp it is NOT native Butterflyweed and most is most likely a variety of Tropical Milkweed. Let's go into more detail.

For the rest of this post, I will be using the scientific names for the different milkweed plants. This is to help encourage people to learn and utilize scientific names to help identify plants in nurseries.

FOR A QUICK SUMMARY please scroll down to see a quick summary of the distinguishing characteristics for these look alike milkweeds.

Flowers

Tropical Milkweed (Asclepias curassavica) commonly has red and yellow flowers. Typically the upright hoods are yellow and the downward facing petals are red. Asclepias curassavica is the only milkweed with red and yellow colored flowers. So you can immediately assume that plant is Asclepias curassavica. This can be the easiest distinguishing feature between Asclepias curassavica and two look-alikes - Butterflyweed (Asclepias tuberosa) and Fewflower Milkweed (Asclepias lanceolata).

However, a variety of Asclepias curassavica has orange hoods and petals. This makes it hard to distinguish them from Asclepias tuberosa which also has orange flowers.

For further identification you should move on to the leaves.

Leaves

Asclepias curassavica has narrow leaves that come to a point at the end at approximately 5" long. Milky white sap inside leaves and stems that seeps when broken.

There is a variegated variety of Asclepias curassavica that are easily identified with their white and green leaves.

Asclepias tuberosa tends to have smaller leaves - both shorter and narrower. Additionally, Asclepias tuberosa does not contain a milky sap that can be expressed when tearing a leaf.

Asclepias lanceolata has longer and fewer leaves in number than both of previously mentioned milkweeds.

Asclepias curassavica leaves can appear similar to Pink Swamp Milkweed (Asclepias incarnata). They are both slender, pointed, and contain the milky sap. But, as you can guess by the name, Pink Swamp Milkweed has easily distinguishable pink flowers.

Mature Height

Mature height is obviously not a useful diagnostic tool when trying to choose plants at the store that are all going to be younger plants. But there is a useful mature height difference between Asclepias curassavica and Asclepias tuberosa in that Asclepias curassavica gets much taller and leggier than Asclepias tuberosa. The mature height of Asclepias curassavica can be up to 4 feet tall whereas Asclepias tuberosa typically maxes out at 3 feet but is commonly only 2 feet tall.

Asclepias curassavica and Asclepias incarnata reach similar heights. Because their leaves and plant shape are similar, this can make plants that have not bloomed yet hard to distinguish. Remember that Asclepias incarnata has soft pink blooms vs orange and red flowers on Asclepias curassavica

Asclepias lanceolata can reach similar heights as Asclepias curassavica and even be taller. However, the leaves and blooms are easily distinguished from Asclepias curassavica that height should not be needed for identification.

Seed Pods

Another tool for identification of Asclepias curassavica vs Asclepias tuberosa is comparing the seed pod. Asclepias curassavica sets a vibrantly green and smooth seeds pod. Contrastingly, Asclepias tuberosa seed pods are a dull green and covered with pubescence (small hairs) easily seen and felt.

Habitat (Outside of Gardens)

Asclepias curassavica can thrive in a wide range of conditions. But, it prefers to be in an area that has moist soil with some shade. Asclepias tuberosa is the opposite. It prefers full sun and dry sandy soils.

Time of Year

Asclepias curassavica is the only milkweed discussed thus far that grows coninously year around. Although native milkweeds are also perennials, most native milkweeds will die back and become dormant in the winter. Therefore, any milkweed resembling Asclepias curassavica seen in the winter is assumed to be just that.

Summary

Tropical Milkweed Asclepias curassavica:

Flower Color: Orange and red; Orange depending on variety

Leaves: Green or Green and white depending on variety; Narrow and terminate into a point; average approx 5" long

Mature Height: 3-4 feet tall and leggy

Seed Pods: Vibrant green, smooth, narrow before drying out and turning brown and releasing seeds

Habitat: Native to Mexico; thrives in almost any condition in Florida

Time of Year: Grows and blooms continously all year long

Butterflyweed Asclepias tuberosa:

Flower Color: Orange

Leaves: Tend to be a little darker green, narrower, and shorter than other milkweeds with a more rounded tip; average approx 3-4" long

Mature Height: 2-3 feet tall average 2 feet tall

Seed Pods: Dull, pale green covered with small hairs that can be seen and felt before drying out, turning brown, and releasing seeds

Habitat: Prefers full sun and dry sandy soils but will tolerate some shade in an understory with dry sandy soil

Time of Year: Blooms appear in summer and late summer before plant goes dormant in the winter

Fewflower Milkweed Asclepias lanceolata

Flower Color: Rich dark red and orange

Leaves: Much longer and narrower than other milkweeds; approx 8" long

Mature Height: 5 feet tall

Seed Pods: Develop under flower's umbell

Habitat: Prefers sunny, wet, swampy habitats, wet pinelands

Time of Year: Bloom late spring into fall before going dormant in the winter

Pink Swamp Milkweed Asclepias incarnata

Flower Color: Pale Pink

Leaves: Green, narrow, and terminate into a point; average approx 5-6" long

Mature Height: 3-4 feet tall

Seed Pods: 4-5" green pod typically produced in the fall prior to dormancy in which they dry out and turn brown before releasing seeds

Habitat: Sunny wetlands, soggy soils, swamps,

Time of Year: Bloom late spring into summer; dormant in the winter

Florida Native Milkweeds You are Most Likely to Find in Nurseries

Swamp Milkweed (Asclepias incarnata)

Aquatic Milkweed (Asclepias perennis)

Butterflyweed (Asclepias tuberosa)

Need Help Finding Florida Natives?

https://www.fann.org/ - Florida Association of Native Nurseries

https://www.fnps.org/ - Florida Native Plant Society

Other Useful Websites related to this topic:

https://bplant.org/compare/261-10009 - Butterfly Milkweed vs Tropical Milkweed

https://www.fnps.org/assets/pdf/palmetto/Palmetto%2038-4_Milkweed_Messec.pdf - Tropical Milkweed: Harmful to Monarchs and Florida Ecosystems

https://xerces.org/sites/default/files/publications/19-020.pdf - Milkweeds of Florida

What are your thoughts? Do you have any useful tips or tricks in identification of native milkweeds? Feel free to comment below to keep the conversation going.