Native Milkweed Seed Needed to Help Save Monarch Butterflies

The Xerces Society needs your help:
  • Monarch butterfly populations are declining, in part due to declining milkweed populations
  • Few commercial sources for milkweed seed are available for the Southeastern regions
  • The Xerces Society has funding to increase seed sources, and is collecting seed now
  • The seed of the aquatic milkweed, Asclepias perennis is scarce this year, and they are seeking our help in locating and collecting seed from this plant
Swamp milkweed, Asclepias perennis

Commonly called 'swamp milkweed' or 'aquatic milkweed,' A. perennis can be found in a variety of wetland habitats, from swamps to roadside swales. It flowers more freely in sunny locations, but tolerates semi-shaded spots as well. The leaves are bright green and lance-shaped and opposite, the height no more than two feet. The white flowers are sometimes tinged with pink.

The species is currently flowering and producing fruit.
If you can locate a plant on private land and are willing to collect some seed and donate it to the project, it would be immensely helpful!  Jeff Norcini, who is helping with the search, has provided some advice  to help determine when the fruits are mature and ready for seed collection.

Immature pod of A perennis     Shirley Denton, FNPS

Maturity checklist 
  • immature pods are grass green and gradually darken a bit as they mature 
  • pods take about 2.5 to 3.5 weeks to mature after the fruit first forms

    • mature pods will pop open when pressure is applied to the pod suture
          Unlike most of the other milkweed species, swamp milkweed seeds are not characterized by feathery white attachments to help them become airborne. Swamp milkweed seeds are hydrochorous, or dispersed by water, and have to be prepared to float to new homes.

          Swamp milkweed in water        Shirley Denton, FNPS

          Brianna Borders, who is now holding the job of Xerces' first dedicated plant ecologist, (insects do need their native plants!) spoke with us yesterday to explain the situation. Intensifying agriculture, development of rural lands, and increased use of herbicide and mowing along roadsides have all reduced the abundance of milkweed in the landscape.  Unfortunately a known source of swamp milkweed was mowed down earlier this month, preventing Dr. Norcini from obtaining seeds there. As most of our readers probably know, milkweed is an obligate host plant for Monarchs. The monarch caterpillars must hatch out on milkweed, which is the only plant they can eat.

          Here in the Southeast, we are somewhat behind our neighbors in the mid-Atlantic and mid-west, where commercial sources of milkweed seed are readily available. In order to increase the commercial availability of milkweed seed, Xerces has obtained funding from several sources, including the NRCS (Natural Resources Conservation Service). They also have joined with the Monarch Joint Venture, a partnership of federal and state agencies, NGOs and academic programs that are working together to support and coordinate efforts to protect the monarch migration across the lower 48 states.

          Fall migration of Monarch butterfly
          There is only one species, but it is divided into an eastern
          and a western population

          The Monarch population is divided into two populations, although they are just one species; the eastern and the western. It is the eastern population that breeds in and migrates through Florida. In addition to Florida, Xerces is also conducting the milkweed seed increase project in Arizona, California, Texas, Nevada, and New Mexico. Brianna tells us that in each state different arrangements and coalitions have been formed. In California and Texas, Xerces is working with private native seed producers to develop new sources of milkweed seed.

          Brianna emphasized that it is extremely important to obtain true Florida ecotype seeds.  If you purchased your plants or seeds from an online vendor, they may not have originated here and would be unsuitable. After the seeds are collected, in Florida they will be grown out by the NRCS Plants Material Center in Brooksville. I had never heard of the NRCS' Plant Materials Program, which Brianna explained as an organization working on developing plants to solve conservation problems. And thank goodness for that!!

          As the seed base is increased, the first recipients will be agencies and organizations that are conducting large scale restoration endeavors, to ensure that the greatest amount of land is covered by the new milkweed plants. Brianna says, "We have a small amount of Asclepias perennis seed that we will use to initiate seed increase for the species, but to maximize our efforts, we could really use some additional seed."

          Here is regional, county-level map from the Florida Atlas of Vascular plant for swamp milkweed:
          Regional map for Asclepias perennis

          You can search Craig Huegel's blog for more ID photos, and other types of milkweed:

          Read about ecotypes:

          Time is short, collecting on public lands requires lengthy permitting processes; please look around and see if you can help. Seed should be saved at room temperature in a paper bag, no plastic, and contact Brianna for instructions on where to ship. She can help reimburse mailing costs if needed.

          Monarch caterpillars MUST have milkweed!
          Toll free: 1-855-232-6639

          Be a part of the solution!

          Monarch migration
          sue dingwell


          Asclepias perennis on the roadside mowed down before it could reseed -- how many times does this have to happen? We need more intelligent roadside vegetation management and more natives on the roadside and YOU can help make it happen. Support the Highway BEE Act:
          daisy g said…
          Sorry, I only have native Florida milkweed, not the swamp variety.
          Anonymous said…
          I have yellow flowered and pink flowered milkweed. I have no idea of the species name, but the Monarchs are currently actively ovidepositing on them! Earlier this year, I had Queen caterpillars feeding on them. I'm in Palm Beach County.
          So right, Cammie,and thanks for bringing the Act to our attention,going on Facebook next. Hope all our readers go and check "I support" Here is part: The bill promotes conservation practices on 17 million acres of highway rights-of-ways (ROWs) by encouraging reduced mowing and native plantings that provide improved habitat for pollinators, ground nesting birds and other small wildlife. No new monies are requested and this bill is designed to save money for states..." Yes!
          Daisy, thanks as always for your loyal following; we know you would give seed if you had it!!

          Palm Beach County milkweed grower, you are so lucky! Send us some pictures if you can! ( If you want to ID your different species, here is link with photos of the kinds that grow in your area:

          Hobo Botanist said…
          Although not commonly cultivated in South Florida, the native Asclepias incarnata is perhaps the best bet for us down here as A. perennis has northern leanings. Native forms of the common A. tuberosa are too difficult to grow, and do not last long in the landscape. (not to mention that I have never seen monarch larva on its leaves in the wild). A. incarnata is large, with good fleshy leaves, its one drawback is that it needs its feet wet, so would be good for a rain garden or a water feature.
          Anonymous said…
          I am in Daytona Beach/Orlando area, and my milkweed has been totally destroyed by fungus. My caterpillars are hungry and almost out of food! If anyone has some milkweed they can donate, I'd really appreciate it, as would our monarch cats! Please email me at: boozapianAThotmailDOTcom. Thank you!
          Jabari Lee said…
          Do you mean that you have Butterflyweed (Asclepias tuberosa) when you say Florida native milk weed? If so, do you have any seeds available that you would be willing to trade? Send me an email at Thank you

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