En Español

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?


Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

rate this answer
Not Yet Rated

Tuesday - November 01, 2011

From: Austin, TX
Region: Southwest
Topic: Butterfly Gardens, Poisonous Plants
Title: How toxic are milkweed (Asclepias spp.)?
Answered by: Nan Hampton


We are considering a monarch waystation for our local elementary and are concerned about milkweed toxicity. Would it be safe to plant it in reach of children?


The Poisonous Plants of North Carolina database says that all parts of Asclepias species are poisonous, but are "Toxic only if large quantities are eaten."  The Toxic Plant Database of Purdue University Veterinary School agrees with this assessment.  Moreover, the plants are generally unpalatable.  Grazing animals don't readily eat them unless they are confined in a pasture with large numbers of plants or the plants have been included in hay given to them.  The compounds that are toxic in the milkweeds are cardiac glycosides.  The monarch larvae eating the plants sequester these toxins in their exoskeletons where they remain even after they metamorphose into butterflies.  Not only do they make the butterflies taste bad, but the glycosides have an emetic effect that causes a predator, such as a bird, to vomit.  Predators apparently remember and associate the butterflies with the unpleasant taste and learn to avoid eating the monarch.

According to the Botanical Dermatology Database, several species of the family [e.g.,  Asclepias viridis (Green antelopehorn)] can cause dermatitis from the milky sap so you should probably protect the plants to keep them from being broken and exuding the sap.

Since milkweeds are unpalatable and they don't contain attractive fruits that might tempt the children to eat them, I don't think that you should be overly concerned about including them in your butterfly garden. 


More Poisonous Plants Questions

Is mulch from hackberry and chinaberry trees safe for flowerbeds?
September 17, 2014 - We had to remove several large hackberry and china berry trees. Is its mulch safe to use in garden and in flower beds?
view the full question and answer

Cenizo safe for consumption by parrots from Phoenix AZ
April 30, 2012 - Could you tell me if Cenizo, (Leucophyllum frutescens) branches and leaves can be fed to pets? (parrots)I read the leaves were often used for tea for humans, but can't find an information if safe fo...
view the full question and answer

Plant ID from Villa Hills KY
April 21, 2013 - Hello I have this plant but I don't know what it is. I want to know if it's edible or what it is. I think it's catnip.
view the full question and answer

Is Poison ivy always rooted in the ground?
November 11, 2015 - Does Poison ivy on a tree always start at the ground and climb up the tree or can it start producing its vine and leaves by itself at the top of the tree or middle?
view the full question and answer

Toxicity of Texas Mountain Laurel seeds to livestock and dogs?
March 09, 2011 - Are the seeds of the Texas Mountain Laurel poisonous to livestock or dogs? Thanks
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center