Host an Event Volunteer Join Tickets

Support the plant database you love!

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?

Share

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
1 rating

Saturday - August 24, 2013

From: Richmond, TX
Region: Southwest
Topic: Non-Natives, Poisonous Plants
Title: Does non-native Crown of Thorns cause cancer?
Answered by: Nan Hampton

QUESTION:

Does the plant, Corona De Cristo (Crown of thorns) cause cancer?

ANSWER:

First of all, the focus and expertise of the Lady Bird Johnson Wildflower Center is with plants native to North America.  Euphorbia milii (Crown of Thorns) is native to Madagascar and, thus, is really out of our purview.  However, I can point you to several internet sources where you can find out more about it.

Poisonous Plants of North Carolina lists it as being mildly toxic and, according to the University of Florida Miami-Dade Cooperative Extension Service:

"As with other euphorbs, E. milii produces copious quantities of poisonous milky sap that can cause skin irritation, and contains tumor promoting chemicals (diterpene esters).  It would be best to wear gloves when handling the plants, and to wash off any sap that gets on your skin."

Here is more information from Union County College in New Jersey.

There are rumors about the plant having cancer causing abilities and several of the sites listed above note that the sap has chemicals that are known tumor promoters.  However, a study testing the sap on mice skin did not produce tumors.  [Delgado, I. F. et al.  2003. Absence of tumor promoting activity of Euphorbia milii latex on the mouse back skin.  Toxicol. Lett. 2003 Nov 30;145(2):175-80.]

If I were you, I would use caution in handling the plant and, as the advice from Miami-Dade Cooperative Extension Service recommends—wear gloves and wash off any sap that gets on your skin.

 

More Non-Natives Questions

Alternatives to non-native, invasive Pampa grass
August 11, 2006 - Could you please tell me if Cortaderia Selloana is "zone 4" hardy? Also how to start Opuntia Humifusa from cuttings? Do I let them stand upright dry and with no soil until they form the callous? Ple...
view the full question and answer

Seeds of agave attenuata from San Diego CA
April 16, 2012 - After the agave attenuata bloom dried up there are seeds like thing hanging on the foxtail; do I leave it until it dies or do I chop that down. Are those seeds for propagation. The leaves of the plan...
view the full question and answer

Tecoma stans problems in Santa Monica CA
September 20, 2010 - I just purchased a mature 6ft tall potted Tecoma Stance Vine (Honeysuckle), It is placed in an area where it gets at least 3 to 4 hours morning/early afternoon sun and then a shaded sun for the rest o...
view the full question and answer

Japanese lilac trees in Lehi UT
July 31, 2010 - Dear Mr. Smarty Pants, We live in Utah and this past spring planted three Japanese Lilac Trees in the lawn next to the deck hoping they would one day provide some shade. They are planted in full sun ...
view the full question and answer

When to Move Potted Plants Outside in Texas?
July 07, 2016 - When can I move my potted patio plants back outside? I live in Heath/ Rockwall, Texas. I have Horses tail, Croutens, and Money tree.
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.