Cynanchum (Blue Vine) "Milkweed" unsafe for Monarchs?

[applestar]

Some one just pointed me to this bit at http://www.fs.fed.us/monarchbutterfly/h ... ndex.shtml

A Few Bad Milkweeds

There are a several native and introduced milkweed plants in the genus Cynanchum (swallow-worts) that are also eaten by monarchs. Swallow-worts have similar chemical properties to milkweeds in the genus Asclepias, that fool monarchs into laying eggs on them. Cynanchum species are not suitable food for monarch larvae. Caterpillars fail to develop into pupae when feeding on them. Please do not plant these milkweeds in your garden.

Is it true? I just grew some from seed this spring and the vines are growing nicely, about 5ft high, on my fence and gate arbor....

[Mona Miller]

They can use Cynanchum (Blue Sandvine), it is not toxic.
Cynanchum laeve
http://plants.usda.gov/java/profile?symbol=CYLA

http://www.nps.gov/plants/alien/fact/cylo1.htm
"Cynanchum louiseae (Black Swallow-wort)
Investigations into impacts on the monarch butterfly, which requires milkweeds for reproduction, indicate that the butterfly will cue into black swallow-wort and lay eggs, but the larvae do not survive.
DISTRIBUTION IN THE UNITED STATES
Black swallow-wort has been reported to be invasive in natural areas in California, Connecticut, New Hampshire, New York, and Wisconsin."
http://plants.usda.gov/java/profile?symbol=CYLO11
Looks like C. louiseae is in more states now.

I might have seeds of the C. laeve this year. I'll let you all know.

[applestar]

Oh WHEW! Thanks Mona. I believe that means mine are OK. They definitely have heart-shaped leaves.

[Mona Miller]

Imagine this.... A large corn field grown, adjacent to the Potomac River. The area has a flower garden that is grown by my preschool friend who is earning some summer cash by selling cut flowers. The Monarchs are nectaring on those flowers. She also plants tropical milkweeds. But, in the fields of corn long ago picked and sold are Blue Sand Vine growing. The owner of the corn field is her brother and he knows that the Monarchs are using the Sand Vine so he leaves it until late fall before he turns it over. My preschool friend grows Monarchs with the kids every fall.

[crazymilkweedman]

another case of Internet ..monkey see monkey say...ALOT of Internet(mis) information is out there. people copying bad articles and such. The biggest problem is that the same plant can have 10 different or overlapping (regional common)names from state to state..like a sand vine one place is a blue vine in another and a white vine in yet another..stick with the scientific name an you'll be good to go!

[milkweedman]

I'm desparate for some seeds of Honeyvine/Sandvine milkweed (Cynanchum laeve)!!!
I had some plants growing but they rotted at the roots so unless they miraculously reappear I will need fresh seed.
Can't seem to find seed on ANY commercial seed site accross the USA.
Can someone seed me some and I'll reimburse with concealed cash or bank transfer? I'm in New Zealand though, but getting seeds in the mail hasn't been a problem so far! Thanks for any help!