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

Thursday - April 23, 2009

From: Lebanon, IN
Region: Midwest
Topic: Non-Natives
Title: Toxicity of non-native Royal Empress tree
Answered by: Barbara Medford


We want to plant some fast-growing trees for shade for my horses. My friend wants to use Royal Empress trees. Can you tell me if these are toxic to horses (and also goats)? I have a lot of clay in the soil on my property.


The first thing we want to do is urge you NOT to plant the Royal Empress tree, for reasons you will learn from this Plant Conservation Alliance Alien Working Group website on Paulownia tomentosa. It is a native of western and central China, and can quickly become invasive, crowding out or destroying more desirable native plants. As in the case in other fast-growing trees, it is a weak tree and not long-lived. At the Lady Bird Johnson Wildflower Center, we recommend only plants native not only to North America but to the area in which the plants are being grown. Plants native to an area will be adapted to the climate, rainfall and soils, and require less fertilizer, water and maintenance.

Now, for what plants are poisonous to horses, excerpted from a previous Mr. Smarty Plants answer:

Answer: First of all, Mr. Smarty Plants wants to refer you to some plants to AVOID for your horses.  Please see the lists from the following sources:

10 Most Poisonous Plants for Horses from EquiSearch.com

Poisonous Plants from Trailblazer Magazine

Toxic Plants: Horses from the ASPCA

Horse Nutrition: Poisonous Plants from Ohio State University

Next, Mr. Smarty Plants refers you to our Recommended Species page to find native plants that are commerically available in Indiana.  You can select 'Indiana' from the map or pulldown menu and then NARROW YOUR SEARCH by selecting 'Tree' from the Habit (general appearance) option.

You might also check for recommended species near your area (Boone County) on the Indiana Native Plant Society website.

Finally, Mr. Smarty Plants refers you to some toxic plant databases that you can check for the plants you like.  These would be:  Poisonous Plants of North Carolina, Cornell University Plants Poisonous to Livestock, Texas Toxic Plant Database, and University of Pennsylvania Poisonous Plants.  When you find a tree that you would like to plant in your pasture, you can compare it with these lists to see if it is safe for your horses.  From the Indiana Recommended species list mentioned above, Mr. Smarty Plants has chosen several species and checked them against the toxic plant databases.  These species are:

Carpinus caroliniana (American hornbeam)

Carya ovata (shagbark hickory)

Platanus occidentalis (American sycamore)

Carpinus caroliniana


Carya ovata

Platanus occidentalis

More Non-Natives Questions

Freeze damage to my Norfolk Island Pine in Houston, TX
March 18, 2010 - Houston, Texas experienced a rare 3-day snow event this winter that allowed snow to stay on my 20 ft. Norfolk Pine, in the ground for over 10 yrs. Every branch is now brown with all dead foliage. I ha...
view the full question and answer

What about Asian Jasmine and scrub oaks?
September 01, 2010 - Dear Mr. Smarty Plants, I have several clusters of native scrub oaks in my yard. I planted Asian jasmine under them many years ago. The trees look fine, but an arborist has told me that the Asian ...
view the full question and answer

Problems with non-native bi-color iris from Spring Branch TX
August 18, 2011 - Bi colored iris. I have four plants planted around our water feature last fall. Up until recently they all looked very healthy, yet not blooming. Several weeks ago I noticed that two of the plants ...
view the full question and answer

Baby in a manger plant from Rock Hill SC
June 28, 2010 - I'm looking for the correct name for baby in a manger(It's a plant.)
view the full question and answer

Ways to eliminate non-native bermuda grass from West Columbia SC
July 01, 2010 - Could you kill bermuda grass by heavy over-fertilizing it? Or black, solid plastic cloth? 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