Honey-Vine Climbing Milkweed,  Sand Vine, Honey Vine, Blue Vine Milkweed, Honeyvine Milkweed

Cynanchum laeve

sigh-NAN-chum  LEE-vey

Synonyms of Cynanchum laeve (10) (Updated on 11-17-23 from Plants of the World Online): Ampelamus albidus (Nutt.) Britton (1894), Ampelamus laevis (Michx.) Krings (2001), Ampelamus riparius Raf. (1840), Enslenia albida Nutt. (1818), Enslenia cinerea Spreng. (1824), Gonolobus laevis Michx. (1803), Gonolobus nuttallianus Spreng. (1824), Gonolobus nuttallii Decne. (1844), Gonolobus viridiflorus Nutt. (1818), Vincetoxicum gonocarpos var. laevis (Michx.) Britton (1894)

Cynanchum laeve (Michx.) Pers. is the accepted scientific name for the species. It was named and described as such by Christiaan Hendrik Persoon in Synopsis Plantarum in 1805.

The genus, Cynanchum L., was named and described by Carl von Linnaeus in the first volume of the first edition of Species Plantarum in 1753.

Ampelamus laevis (Michx.) Krings is another commonly used scientific name for this species that is now considered a synonym. It was named and described as such by Alexander Krings in Sida; Contributions to Botany in 2001. It was first named and described as Gonolobus laevis by André Michaux in Flora Boreali-Americana in 1803.

The genus, Ampelamus Raf., was named and described by Constantine Samuel Rafinesque in American Monthly Magazine and Critical Review in 1819.

As of 11-17-23 when I am updating this page, Plants of the World Online by Kew lists 262 species in the Cynanchum 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 Ampelamus laevis is from Plants of the World Online by Kew. Areas in green are where the species is native. The map on the USDA Plants Database is the same but shows the species as introduced in Ontario, Canada instead of being a native.

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.

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

When I was a kid, I remember morning glories coming up in the garden and climbing on the sweet corn. The same is true here in the garden… The first “weeds” to come up after the garden is tilled are the morning glories. Ummm. Except for one thing… In 2021, there was one climbing on the asparagus, and a few were on the sweet corn. I thought they were morning glories and I could get some photos so I let them grow. Well, when they flowered, they were NOT morning glories at all. They turned out to be Cynanchum laeve, the Honey-Vine Climbing Milkweed. I didn’t get good photos in 2021, but they came up in the ditch along the street in front of the garden in 2022 so I took photos.

When I first identified this species as Cynanchum laeve from iNaturalist, most websites and databases were using that name… Except for Plants of the World Online. POWO was using Ampelamus laevis at the time, so I pretty much stuck with that name until the other sites made updates. Then on 11-12-22 when I was making updates, POWO had changed to Cynanchum laeve so I had to change the name back again… They are usually the first to update name changes, which they did. The other sites just hadn’t changed from Cynanchum laeve. For some reason, POWO switched back… You just never know…

Cynanchum laeve is a native perennial fine in the plant family Apocynaceae (Milkweeds). It is found throughout much of Missouri and common to scattered from the central part of the U.S. eastward and up into Canada. This species can be identified by its vining habit, fairly long heart-shaped leaves, and clusters of small aromatic flowers. 

Plants prefer growing in full to part sun in a variety of soil types. They like damp conditions but can be quite drought-tolerant. They can be found in a variety of habitats including bottomland forests, thickets, streambanks and pond margins, fields, gardens flowerbeds, fencerows, and so on. They like vining on just about anything they can climb on. They are sometimes grown as a vining and flowering ornamental… 

The vines grow from a root system consisting of a taproot and long rhizomes. The vines can grow fairly long, at least 20’ or more, are light green to reddish green, and can have longitudinal lines of hairs (especially toward the tips). Vines can be hard to eradicate because plants can grow from the roots left behind when pulling them up. The stems produce a clear to cloudy toxic latex sap, so it is best to use gloves if you pull them up and avoid skin and eye contact.

The opposite leaves grow to about 6” long and 2” wide on petioles (leaf stems) that are about 3” in length. In shape, the leaves are mainly long heart-shaped (triangular-ovate, triangular-cordate) with deeply cordate bases. The area (sinus) between the basal lobes is nearly square (quadrate). The leaves are glabrous (not hairy) except maybe along the veins. The leaves do not have sap.

Clusters of 5-40 flowers grow from 1-3” long peduncles from the axils of the leaves. These peduncles are fairly hairy (pubescent). 

Each flower is surrounded by a light green calyx with 5 lanceolate lobes, a white corolla with 5 lobes that are narrowly oblong to lanceolate that are sometimes pink tipped. The corolla lobes are kind of twisted and semi-erect. In the center is a corona that surrounds the reproductive organs and is divided into 5 segments, each segment having 2 linear lobes that are also twisted.

The blooming period is from July through September. The flowers attract various species of small bees, flies, wasps, and butterflies. Monarch Butterfly caterpillars feed on the leaves.

If pollinated, the flowers produce fruit called a follicle. The follicles are about 4” long and 1” across and splits open once it dries and turns brown. The seeds have large tufts of hair that carry them through the wind.

Missouri Plants is my number one website for verifying wildflower species on the farm and other areas close to where I live. The website has great photos and descriptions and has been a great help. Photos can be used for non-commercial educational uses with proper captioning. There is a link below for their page for Cynanchum laeve, or you can click HERE.

The above photo is of Cynanchum laeve (Honey-Vine Climbing Milkweed) on the right, and Convolvulus arvensis (Field Bindweed) on the left. They were growing together in the ditch.

I plan to take more and better photos in 2024 so I can replace what I have borrowed.

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
DAVE’S GARDEN
MISSOURI PLANTS
MSU-MIDWEST WEEDS AND WILDFLOWERS
MISSOURI DEPARTMENT OF CONSERVATION
UNIVERSITY OF MISSOURI-WEED ID GUIDE
iNATURALIST
WILDFLOWER SEARCH
ILLINOIS WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
IOWA PLANTS
MARYLAND BIODIVERSITY PROJECT
IN DEFENSE OF PLANTS
SEINet
SIDEWALK NATURE
VIRGINIA TECH

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. Plants of the World Online by Kew is a very reliable and up-to-date plant database 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. 🙂