2023 Update: Asclepias viridiflora demography

In spring 2023 we planted about 100 Asclepias viridiflora seedlings in plugs to transects at site eth. The planting data sheets with all details are in Jared’s office. We did not monitor these seedlings after planting.

During summer 2023, we collected demographic data on 172 individual Asclepias viridiflora plants across 17 sites. We also collected 52 seed pods from 26 maternal plants.

A very charismatic cryptid

Dathon Maton and Mary Ashley at the University of Illinois at Chicago have made great progress genotyping tissue collected from seedlings and potential parents in remnant populations. These genetic data coupled with our spatial and demographic data will help us understand the genetic structure of milkweed populations and patterns of gene flow within and among remnants.

  • Start year: 2021
  • Location: 17 patches of remnant tallgrass prairie near Solem Township, MN
  • Overlaps with: burnRems
  • Data collected: Spatial and demographic data have been curated and are housed within the remav repo. Harvested pods have been cleaned, counted, and x-rayed but need to be classified.
  • Samples or specimens collected: 2023 harvested seeds are in Jared’s office. Previous year’s seeds were returned to remnant populations.
  • Products: Stay tuned!

You can read more about the Asclepias viridiflora demography experiment, as well as links to prior flog entries about this experiment, on the background page for this experiment.

Hi milkweed, bye Alex, what’s an emergence trap?

On a hill planting milkweed

We know each plant’s mother.

From every milkweed seed,

Distinct one from one another.


Chocolate cake and thin mints

For Alex’s last day!

We’ll try to follow in her footprints

And maybe make her stay.


Experiments in efficiency-

Catching bugs the best way

Practice until proficiency

How do you catch bugs and make them stay…?


Emergence traps! are tents for bugs

That they can not get out of

So we can see each fuzzy mug

And identify and count them up all up so we know which ones appreciate a post fire environment and which ones do not.

2022 Update: Asclepias viridiflora demography

In summer 2021, Team Echinacea collected data on 70 Green Milkweed (Asclepias viridiflora) plants across 8 patches of remnant prairie in our study area in western MN. During summer 2022, we revisited these same individuals and found 58 additional plants. We collected demographic data on all 128 plants and harvested 52 seed pods. We will score ovules to quantify what proportion contain embryos, grow seedlings, and sow seed in western MN to propagate this species.

In addition to our reproductive and demographic work, we began collaborating with Mary Ashley and her group at the University of Illinois at Chicago to learn more about the genetic structure and mating patterns of green milkweed in fragmented prairie remnants. We collected tissue samples from 100 plants in the field. Mary’s research group is now extracting DNA and genotyping plants.

  • Start year: 2021
  • Location: Remnant patches of prairie in and around Solem Township, MN
  • Overlaps with:
  • Data collected: Spatial, demographic, and seed data are housed in the remav Bitbucket repository
  • Samples or specimens collected:
    • Seeds: 2022 harvest has been cleaned, counted, randomized, and X-rayed but still needs to be classified.
    • Tissue samples: tissue samples are at UIC
  • Products: Stay tuned!

You can read more about the Asclepias viridiflora demography, as well as links to prior flog entries about this experiment, on the background page for this experiment.

The Asclepias Project

Here at the Echinacea Project, we have decided that we have more than enough data to answer all of our questions about Echinacea. Echinacea angustifolia is yesterday’s news. We have therefore decided to become the Asclepias project! 

Asclepias viridflora (green milkweed) is similar to angustifolia in that both are self-incompatible perennial forbs native to Minnesota’s tall-grass prairie. Not much is known about viridiflora, including how it reacts to fire. Does fire promote survival, population growth, and reproduction in Asclepias viridiflora, as it does in Echinacea? If it does, that would bolster our assumption that Echinacea is a good model organism for prairie research. It would also provide vital data on the effects of prescribed burns.

For these reasons, we are tracking green milkweed vitality in prairie remnants. Some of the sites we are looking at were burned in the fall or spring, while others have never burned. Last year, 71 green milkweeds were found across 8 remnants. This year we revisited the locations of those 71 plants, most of which were still there. The team also found 41 new plants. All together we’ve found over 80 live plants!! 

Milkweed has clusters of flowers called umbels. At this point in the summer, most green milkweed umbels have senesced and fallen off, and pods are forming. We will revisit and count these pods later in the season. The data we are collecting includes status (present or not); umbel, pod, and stem count; and leaf width. 

Nice big Milkweed pod.

As the only team member without a car, I’ve really appreciated rides from Daytona and Joey out to the remnants. I couldn’t ask for better partners to help me find and stake/survey milkweed.

Daytona ponders Asclepias (and life) at Hegg.
Joey bears the cross at Staffanson.

Daytona, Joey, and I (Johanna) have also been taking turns naming all the new milkweed plants we’ve come across. Here is a comprehensive list: 

Tedward “Teddy”

Mary Jane


Spronkle Axil


Mark Watney

Björn Ironsight


Barbra Lou

Turtle “Turty”


Sammy Simmons

Ilina Anna

Lightning McQueen from Cars 1, 2, and 3

Masterchief from Fortnite

Markiplier “Marky Moo”

Mathilda Ulrike “Math-u”


Dr. Bared Jeck

Chairman Mao

Archie from Riverdale

Brigham Young

Italian Car from “Cars”

Sam Winchester

Henry Kissingmen

Ted Krazinsky (Unabomber)


Tony Hawk, Pro Sk8er


Neutral Radiator Beach House


Not to play favorites, but…Tedward is my favorite.

Stay tuned for more Asclepias updates later this summer!

Green milkweed planting update

Between June 3 and June 12 (2022), members of the Echinacea Project planted 503 Green Milkweed (Asclepias viridiflora) seedlings across four sites in Solem Township. These sites included an area south of Experimental Plot 8 (149 seedlings planted June 3), a hilltop at Hegg Lake WMA (117 seedlings planted on June 9), a disturbed area at Staffanson Prairie Preserve (117 seedlings planted on June 10), and a hilltop at Eng Lake WPA (aka eth, 120 seedlings planted on June 12).

We hope these seedlings grown from locally-collected seed will establish new thriving populations of this declining plant species and provide a reliable seed source for future restorations. They may even provide future research opportunities to learn about the reproductive biology and demography of green milkweed! Thanks to the MN DNR, the Nature Conservancy, and USFWS for giving us permission to plant seedlings.

Planting Asclepias viridiflora

Last summer, we located 71 Asclepias viridiflora (green milkweed) plants in the remnants, and we collected pods from 22 plants. We brought the seeds back to the Chicago Botanic Garden, where Cathy Thomas propagated them at the production greenhouse. We were hoping for 392 milkweed seedlings, but the seeds germinated better than expected, so we now have 505 baby milkweeds!

On Friday, Jared and I planted 149 Asclepias viridiflora plants south of p8. These plants represented 13 maternal lines. We flagged out five 30-m-long transects. Two transects are partially within the west Andropogon pilot plot, and three transects are partially within the east plot. Along each transect, we dug holes with soil knife 1 m apart, watered the holes, and planted the Asclepias plugs. We placed a toothpick 2 cm north of each plant and recorded the toothpick color. We were glad that we decided to add toothpicks; when I returned to water the milkweed plants, they were already nearly impossible to see!

Growing Green Milkweed

This summer we harvested seed pods from 25 Green Milkweed (Asclepias viridiflora) plants in the study area. Green Milkweed is uncommon and seems to be declining in our study area. This species prefers similar habitat to Echinacea. Plants tend to be sporadically distributed across dry prairies on steep hillsides, sandy soils, and well-drained gravelly areas. Our experience has been that flowering plants often fail to produce seed. We rarely find more than a handful of plants that produce pods in a given year.

After harvesting and drying seeds, Jared cleaned seed by removing their fluffy coma. Jared then counted all the seeds and randomly selected a minimum of 30 seeds for x-raying. X-rays revealed variation. Some ovules lacked an embryo , others had whole, intact embryos. Many ovlues fell somewhere in between. They contained embryos that were undersized, shriveled, or fragmented. There was no external evidence of seed predation. The proportion of full ovules ranged from 0 to 100 percent. We are not sure whether “partials” reflect resource limitation and seed abortion, a form of late-acting self-incompatibility, or something else entirely. We are doing some research to help us interpret the biology underlying these patterns.

After cleaning, counting, and classifying, Jared prepared a subset of Green Milkweed seed for germination. CBG’s production greenhouse will germinate and grow 392 milkweed seedlings representing 15 maternal lines. We will plant these seedlings in an area south of P8. Although these plants grow slowly, our hope is that they will be an excellent resource for investigating milkweed pollination in a couple years. We also hope to harvest seed from these plants and include Green Milkweed in our seed mixes for restoration!

2021 Update: Asclepias viridiflora demography

In summer 2021, Team Echinacea searched for and mapped 71 Green Milkweed (Asclepias viridiflora) plants across 8 patches of remnant prairie in our study area in western MN. This denizen of dry prairies is tough to spot and appears to be declining across its range. Our goal is to monitor Green Milkweed individuals in the study area to better understand their demography, responses to prescribed fire, and reproduction. We located and mapped 70 Green Milkweed plants, 59 of which flowered. Of the plants that flowered, 31 produced pods. We harvested pods from 22 plants for further study in the lab and (hopefully) growing some plants from seed.

  • Start year: 2021
  • Location: Remnant patches of prairie in and around Solem Township, MN
  • Overlaps with: NA
  • Data collected: demographic data: ~Dropbox/burnRems/remAv/data2021/ascvir2021.csv
  • Samples or specimens collected: Pods/seed collected during summer 2021 currently reside in Jared’s office. These seeds need to be inventoried, cleaned, counted, and x-rayed.
  • Products: Stay tuned!

You can read more about the Asclepias viridiflora demography project, as well as links to prior flog entries about this experiment, on the background page for this experiment.

The end of summer

As summer’s vibrant greens give way to fall’s golden glow, Team Echinacea remains hard at work in western MN. A skeleton crew is diligently wrapping up the field season. Our most important task is harvesting seed from study species so that we can quantify fire effects on plant reproduction in remnant prairies. Here is a brief update on progress for our focal species:

Echinacea angustifolia harvest: 383/383 plants harvested

Andropogon gerardii harvest: 370/370 plots measured and harvested

Liatris aspera harvest: 202/231 plants harvested

Lilium philadelphicum harvest: 79/80 plants harvested

Asclepias viridiflora: all plants harvested (~30, Jared forgot to check harvest data sheet…)

In addition to wrapping up the harvest, we are beginning to make preparations for fall burns and getting materials organized to implement a seed addition experiment designed to assess fire effects on seedling emergence and survival.