Asclepias syriaca (Common Milkweed)

Asclepias syriaca (Common Milkweed) on 6-16-21, #801-22.

Common Milkweed, Butterfly Flower, Silkweed, Virginia Silkweed

Asclepias syriaca

ass-KLE-pee-us  seer-ee-AK-uh

Synonyms of Asclepias syriaca (15) (Updated on 1-2-22 from Plants of the World Online): Asclepias apocinum Gaterau, Asclepias consanguinea Kunze, Asclepias cornuti Decne., Asclepias fragrans Raf., Asclepias globosa Stokes, Asclepias grandifolia Bertol., Asclepias illinoensis Michx. ex Steud., Asclepias intermedia Vail, Asclepias obtusifolia Kunze, Asclepias pubescens Moench, Asclepias pubigera Dumort., Asclepias serica Raf., Asclepias syriaca f. inermis J.R.Churchill, Asclepias syriaca f. leucantha Dore, Asclepias syriaca f. polyphylla B.Boivin

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

As of 1-2-22 when this page was last updated, Plants of the World Online by Kew lists 205 species in the Asclepias genus. It is a member of the plant family Apocynaceae with 366 genera. Those numbers could change as updates are made on POWO.

Distribution map of Asclepias syriaca from Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/. Retrieved on January 2, 2022.

The above distribution map for Asclepias syriaca is from Plants of the World Online. Areas in green are where the species is native and purple where it has been introduced. The map on the USDA Plants Database for North America is similar.

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 and continually updated as members post new observations.

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

Asclepias syriaca (Common Milkweed) on 7-12-19, #600-2.

The Asclepias syriaca, Common Milkweed, has been growing by the lagoon here on the farm for several years. In 2019 I noticed it coming up in the main pasture and in the back of the farm. It doesn’t really have a chance to grow well in the pasture and hayfields because they get eaten or mowed off before they flower (even though they come back fast). The photos from July 12, 16, and 19 in 2019 were taken on a friend’s farm. This species grows fairly tall.

Asclepias syriaca (Common Milkweed) on 7-16-19, #602-3.

I took A LOT of photos

 

Asclepias syriaca (Common Milkweed) on 7-16-19, #602-4.

 

Asclepias syriaca (Common Milkweed) on 7-16-19, #602-5.

As with all milkweeds, their stems and leaves contain a milky sap that has variable toxicity in the form of cardiac glycosides.

Asclepias syriaca (Common Milkweed) on 7-16-19, #602-6.

The stout stems are densely hairy (densely pubescent) but sometimes hairless (glabrous). They are usually unbranched below the inflorescence (flower stems).

Asclepias syriaca (Common Milkweed) on 7-22-19, #604-9.

 

Asclepias syriaca (Common Milkweed) on 7-22-19, #604-10.

The leaves grow in an opposite manner along the stems and are up to 8” long x 3 1/2” wide. Leaves are described as being broad, oblong or elliptic-ovate, rounded or pointed at the tip. The midribs are usually purplish toward the base. The upper surface is usually hairless but can have very fine, short hairs. The undersides of the leaves usually have very fine, short hairs…

Asclepias syriaca (Common Milkweed) on 7-22-19, #604-11.

 

Asclepias syriaca (Common Milkweed) on 7-22-19, #604-12.

The above photo shows the stems with fine hairs giving it a chalky appearance.

Asclepias syriaca (Common Milkweed) on 7-22-19, #604-13.

The veins of the leaves grow outward from the midrib toward the leaf margins.

Asclepias syriaca (Common Milkweed) on 7-22-19, #604-14.

View from the top showing the opposite arrangement of the leaves.

Asclepias syriaca (Common Milkweed) on the bank of the lagoon on my farm on 8-2-19, #609-2.

The rest of the photos were taken on the farm where I live… There is a good-sized patch next to the lagoon and surrounding area. They are also scattered along the south side of the farm from one end to the other and along the street in front of the pasture.

Asclepias syriaca (Common Milkweed) on 8-2-19, #609-3.

The Asclepias syriaca have been growing on the bank of the lagoon for several years. Now they are growing in the fence row and pasture in front of it. Even though I mow around the lagoon every week during the summer, I haven’t photographed their flowers…

Asclepias syriaca (Common Milkweed) on 8-2-19, #609-4.

Unlike most other Milkweeds, Asclepias syriaca have these distinct seed pods with tubercles…

Asclepias syriaca (Common Milkweed) on 8-2-19, #609-5.

Hmmm…

<<<<2020>>>>

Asclepias syriaca (Common Milkweed) on 7-10-20, #710-12.

Starting to bud…

Asclepias syriaca (Common Milkweed) on 7-10-20, #710-13.

Umbels of flowers grow from the upper leaves… I am running out of words. There are better descriptions below of the flowers…

Asclepias syriaca (Common Milkweed) on 7-10-20, #710-14.

 

Asclepias syriaca (Common Milkweed) on 7-10-20, #710-15.

No matter when it is, the Milkweeds always have insects of some kind somwehere on the plants…

Asclepias syriaca (Common Milkweed) on 7-10-20, #710-16.

 

Asclepias syriaca (Common Milkweed) on 7-10-20, #710-17.

 

Asclepias syriaca (Common Milkweed) on 7-10-20, #710-18.

<<<<2021>>>>

Asclepias syriaca (Common Milkweed) in the southeast pasture on 6-15-21, #800-6.

The above photo is of a colony of Asclepias syriaca in the southeast pasture.

Asclepias syriaca (Common Milkweed) on 6-16-21, #801-21.

The above photo and the next four were taken of a small colony along the fence outside of the front pasture.

Asclepias syriaca (Common Milkweed) on 6-16-21, #801-22.

Typical of Milkweeds, the flowers grow in globose umbels, 2-10 per stem, emerging from the axils of the upper leaves. The umbels contain 20-100 flowers.

Flowers are about 1/4” across, with 5 reflexed petals (corolla lobes), 5 raised hoods with curved horns… You can read the descriptions on the Missouri Plants website for much more technical descriptions… Pollination is quite interesting with all milkweed species. There are several links at the bottom of the page with very good descriptions.

Asclepias syriaca (Common Milkweed) on 6-16-21, #801-23.

These plants by the fence flowered earlier than the rest of the plants on my farm…

Asclepias syriaca (Common Milkweed) on 6-16-21, #801-24.

 

Asclepias syriaca (Common Milkweed) on 6-16-21, #801-25.

 Flowers are about 1/4” across, with 5 reflexed petals (corolla lobes), 5 raised hoods with curved horns… You can read the descriptions on the Missouri Plants website for much more technical descriptions… Pollination is quite interesting with all milkweed species.

Asclepias syriaca (Common Milkweed) on 7-23-21, #818-3.

The above and below photos are of the same plant along the south hayfield.

Asclepias syriaca (Common Milkweed) on 7-23-21, #818-4.

Asclepias syriaca have fruits and seed pods similar to other Milkweeds except that they are covered with narrow warty tubercles… Seeds are distributed by wind with their soft fluffy hairs.

Asclepias syriaca (Common Milkweed) on 9-19-21, #832-1.

A research team from the biology department at Augustana University in Sioux Falls, South Dakota asked if I would participate in their Milkweed research. Of course, I agreed. The green seedpod of this plant in the south hayfield was one of two I sent once it was dried (but not open).

Asclepias syriaca (Common Milkweed) in the main hayfield on 9-28-21, #836-3.

Once the hay was cut, the Asclepias syriaca wasted no time growing again. Unfortunately, they were not able to flower…

Asclepias syriaca (Common Milkweed) on 10-7-21, #841-2.

One of these seedpods from a plant growing in the fence along the front pasture was also sent to the research team.

Asclepias syriaca (Common Milkweed) on 10-12-21, #843-2.

Besides milkweeds being host plants for Monarch Butterfly caterpillars, they are beneficial to many other insects as well. Most of the time when I am photographing, there are multiple species on the leaves. They are either feeding or being fed on…

I will continue taking more photos as time goes by.

I live on a small farm in Windsor, Missouri where I enjoy gardening, collecting plants, and identifying wildflowers. The farm is in Pettis County but Henry County is across the street, and Benton and Johnson aren’t far away. I have grown over 500 different plants and identified over 200 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 somewhat variable from location to location, so sometimes it gets 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)
WORLD FLORA ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
USDA PLANTS DATABASE
USDA PLANT GUIDE
DAVE’S GARDEN
MISSOURI PLANTS
MISSOURI BOTANICAL GARDEN
MSU-MIDWEST WEEDS AND WILDFLOWERS
MISSOURI DEPARTMENT OF CONSERVATION
iNATURALIST
WILDFLOWERSEARCH
ILLINOIS WILDFLOWERS
MINNESOTA WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
NORTH CAROLINA STATE UNIVERSITY
PFAF(PLANTS FOR A FUTURE)
GO BOTANY
LADY BIRD JOHNSON WILDFLOWER CENTER
FLORA FINDER
FRIENDS OF THE WILDFLOWER GARDEN
GARDENIA
U.S. FOREST SERVICE
MONARCH WATCH

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 the most reliable and up-to-date plant database and they make updates on a regular basis. 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. 🙂

 

Please leave a comment. I would like to hear from you.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.