Home » Differences Between Asclepias Incarnata and Asclepias Perennis
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Differences Between Asclepias Incarnata and Asclepias Perennis

White Swamp Milkweed”: A Guide by Johnny Butterflyseed

As an advocate for native plants and the preservation of butterfly habitats, Johnny Butterflyseed is committed to educating enthusiasts about the various milkweed species that support monarch butterflies in Florida and throughout the U.S. Southeast. Today, we focus on two milkweed species that are often the last to be identified in the field due to their subtle differences: Asclepias incarnata and Asclepias perennis.

Identification Key Insights

Based on the USF Atlas of Vascular Plants, here are the critical identification keys for these two species:

Asclepias incarnata:

Leaf blade base: Rounded to short-tapering
Corolla (petals) color: Dull rose-purple

“Rounded”, “short tapering”, and “long tapering” leaf bases are evident in this Asclepias Incarnata.

While there are white flower parts, “dull rose-purple” corolla indicate Asclepias Incarnata.

Asclepias perennis:

Leaf blade base: Long tapering
Corolla color: White to pale pink

With all-white flowers, this can be identified correctly as “Aquatic Milkweed” or as “White Swamp Milkweed” as this image also demonstrates the “long tapering leaf base” associated with Asclepias Perennis.
Perfect, slightly “pale pink” corolla with slender leaves that indicate this Asclepias Perennis likely has “long-tapering” leaf bases, even if they are not visible in the photo. There is no “rose-purple” color at all. Could it simply be Asclepias Incarnata with its flowers bleached and its leaves narrowed by USDA zone 10 full sun?

While these identification keys provide essential guidance, the subtleties in their descriptions can sometimes lead to confusion. Let’s delve deeper into these characteristics.

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