Purple Milkweed

Asclepias purpurascens

ass-KLE-pee-us  pur-pur-ESS-kenz

Synonyms of Asclepias purpurascens  (5) (Updated on 11-16-23 from Plants of the World Online): Asclepias amoena L. (1753), Asclepias compressa Moench (1794), Asclepias dasypus Raf. (1832), Asclepias gonalis Raf. (1840), Asclepias lasiotis Raf. (1840)

Asclepias purpurascens L. is the accepted scientific name for this species of Milkweed. The genus and species name were described as such by Carl von Linnaeus in the first volume of the first edition of Species Plantarum in 1753.

As of 11-16-23 when I wrote this page, Plants of the World Online lists 205 species in the Asclepias genus. It is a member of the plant family Apocynaceae with 376 genera. Those numbers could change as updates are made on POWO.

The above distribution map for Asclepias purpurascens is from Plants of the World Online. Areas in green are where the species is native. The map on the USDA Plants Database is the same. There several maps online to give an idea of there the species may be found. No map is perfect and the species could me more widespread than they show. In some cases, they could only be found in a few areas in the state. Most maps are not up-to-date.

The map on iNaturalist shows where members have made observations. Anyone can join and it is a great website to confirm and share your observations. The maps on iNaturalist are continually updated as members post new observations. I post all my observations on iNaturalist.

THERE ARE SEVERAL LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND TO HELP WITH A POSITIVE ID.

Even though the summer of 2023 was very hot and dry, I still managed to identify several new species on the farm. On June 4 while I was walking through the main hayfield, I spotted this Asclepias purpurascens from a distance. I knew it was different from its bright purple flowers.

Asclepias purpurascens is a North American native perennial easily spotted by its bright purple flowers. They can be found from the Midwestern states into New England and up into Canada. The flowers are a favorite of the Great Spangled Fritillary butterfly.

Information online suggests the species preference is partial sun and mesic-like conditions. They have been found in rocky open woodlands, glades prairies, stream balls, wet meadows and valleys, slopes of prairies, along roadsides. You know, the usual… HOWEVER, I found my first one in the main hayfield in full sun and the beginning of a severe drought. Of course, it had flowers and soon fizzled out after that. 

Asclepias purpurascens usually grows from a single stem, possibly branching out at the top. The stems are green to reddish brown toward the the top, densely pubescent (hairy) mainly toward the tip with fine, soft hairs.

While I was taking photos this magnificent Argynnis cybele (Great Spangled Fritillary) flew in for a visit.

Usually, taking photos of butterflies can be tricky because they are always flying off. This time, it was in no hurry…

It was quite an awesome creature!

Each flower comprises of 5 reflexed green sepals and 5  reflexed corolla lobes (petals). Above the corolla lobes is the corona consisting of 5 hoods each with horns. There is a “slit” between the hoods… Beyond that, I kind of go blank. The corolla lobes and corona hoods can vary in shades of pale to deep purple and reddish purple that are lighter toward the bases. Apparently, the flowers of the lower auxillary umbels start to open first and the others open in succession. 

I found a good write-up called, “The Story of an Organism: Common Milkweed” by Craig Holdrege from The Nature Institute. You Can read it by clicking HERE… It’s quite a story that leaves nothing out about Milkweeds.

Pairs of leaves grow opposite one another and are lanceolate-elliptic, ovate, ovate-oblong, or broadly lanceolate in shape and are up to 6” long and 3” across. The leaves have smooth margins that are sometimes wavy (undulate) and have bluntly-pointed tips. Sometimes the leaves curl upward toward from the central pinkish veins. Depending on light conditions, the leaves can be light to dark green.

The upper surface (adaxial) can have fine hairs (pubescent) or be hairless (glabrous), while the undersurface (abaxial) is lighter green and pubescent (mainly along the veins).

Only a few flowers get pollinated and produce fruit compared to the number of flowers. Pollinated flowers are replaced by seedpods (follicles) that are up to 6” in length. The slightly arched-shaped pods are around 6” long and are smooth or have very fine shorts hairs (so small they appear smooth). The pods contain numerous seeds that have narrowly winged margins and tufts of white hair that are carried away by the wind.

As I mentioned, the flowers are a favorite source of nectar of the Great Spangled Fritillary, but many other species of butterflies also visit. It’s always amazing how many species insects visit milkweeds for various reasons. If you want to photograph and identify many species of butterflies, bees, beetles, etc., find a patch of Milkweed…

I live on the family farm in Windsor, Missouri in Pettis County (Henry County is across the street, and Benton and Johnson aren’t far away). I have grown over 500 different plants and identified over 250 species of wildflowers (most have pages listed on the right side of the page). I am not an expert, botanist, or horticulturalist. I just like growing, photographing, and writing about my experience. I rely on several websites for ID and a few horticulturalists I contact if I cannot figure them out. Wildflowers can be variable from location to location, so that can be a bit confusing. If you see I have made an error, please let me know so I can correct what I have written.

I hope you found this page useful and be sure to check the links below for more information. They were written by experts and provide much more information. Some sites may not be up-to-date but they are always a work in progress. If you can, I would appreciate it if you would click on the “Like” below and leave a comment. It helps us bloggers stay motivated. You can also send an email to me at thebelmontrooster@yahoo.com. I would enjoy hearing from you especially if you notice something is a bit whacky.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
INTERNATIONAL PLANT NAMES INDEX (GENUS/SPECIES)
TROPICOS (GENUS/SPECIES)
FLORA OF MISSOURI (GENUS/SPECIES)
WORLD FLORA ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
USDA PLANTS DATABASE
iNATURALIST
MISSOURI PLANTS
MIDWEST WEEDS AND WILDFLOWERS
MISSOURI BOTANICAL GARDEN
MBG-NATIVE MISSOURI MILKWEEDS…
MISSOURI DEPARTMENT OF CONSERVATION
WILDFLOWER SEARCH
DAVE’S GARDEN
GARDENIA
GO BOTANY
ILLINOIS WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
LADY BIRD JOHNSON WILDFLOWER CENTER
MARYLAND BIODIVERSITY PROJECT
MICHIGAN STATE UNIVERSITY
MINNESOTA WILDFLOWERS
NORTH CAROLINA STATE UNIVERSITY
PFAF (PLANTS FOR A FUTURE)
SEINet
U.S. FOREST SERVICE

NOTE: The data (figures, maps, accepted names, etc.) may not match on these websites. It depends on when and how they make updates and when their sources make updates. Some websites have hundreds and even many thousands of species to keep up with. Accepted scientific names change periodically and it can be hard to keep with as well. Some of the links may use a name that is a synonym on other sites. In my opinion, Plants of the World Online by Kew is one of the most reliable and up-to-date plant databases and they make updates regularly. I make updates “at least” once a year and when I write new pages or add new photos but I do get behind. We are all a work in progress. 🙂