En Espa—ol

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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
rate this answer
Not Yet Rated

Thursday - April 10, 2008

From: Rigby, ID
Region: Rocky Mountain
Topic: Poisonous Plants
Title: Fast growing trees in Idaho
Answered by: Barbara Medford


I want to plant fast-growing trees on my property in Idaho. What trees are poisonous to horses and dogs? I am particularly interested in the Royal Empress (Paulowmia) tree and the dogwood tree.


We don't like to start out with discouraging words, but Paulownia tomentosa is NOT a good choice. We have been asked about it several times, and would like for you to read a previous answer from Mr. Smarty Plants on the subject. Next, read this site from the Plant Conservation Alliance "Least Wanted" List. It appears that some have already escaped cultivation and invaded Idaho; but, under the circumstances, we certainly hope you do not contribute to the problem. The tree is a native of China and, as such, is not normally in the purview of the Lady Bird Johnson Wildflower Center. Our focus and concentration is on plants native to North America; however, we are very interested in invasive plants, especially non-native invasives.

Now, on to the dogwoods, genus Cornus. We found fourteen species of Cornus on our Native Plant Database, of which four can apparently be grown in Idaho.

Cornus canadensis (bunchberry dogwood) This is really a low-growing groundcover type of bush, probably not what you had in mind.

Cornus nuttallii (Pacific dogwood) This USDA Plants Profile shows the areas in Idaho where this species is growing naturally. It is a deciduous tree up to 40 feet tall that does best between 3000 and 8000 feet in altitude. Unfortunately, it is very susceptible to dogwood anthracnose, which has killed many larger plants in the wild and also restricts its use as an ornamental tree.

Cornus sericea (redosier dogwood) Both of these sericea dogwoods are recommended for Idaho, and are useful for erosion control.

Cornus sericea ssp. sericea (redosier dogwood)

Since none of these seem to be the perfect choice, how about some alternatives? First, for the Empress Tree. We went to our Invasives website and found four alternatives to this tree; unfortunately, none of them are recommended for Idaho. So, we went shopping in the Recommended Species for Idaho section and have four tree suggestions. We realize that you wanted fast-growing, blooming trees, but it may be that is not going to happen in Idaho.

Acer grandidentatum (bigtooth maple)

Betula occidentalis (water birch)

Pinus contorta (lodgepole pine)

Prunus virginiana (chokecherry)

And, finally, your question about what trees are poisonous to horses and dogs. Rather than reproduce the list, let us refer you to this Poisonous Plants Informational Database from Cornell University.

Cornus canadensis

Cornus nuttallii

Cornus sericea

Cornus sericea ssp. sericea

Acer grandidentatum

Betula occidentalis

Pinus contorta

Prunus virginiana




More Poisonous Plants Questions

Indoor and Outdoor, Fast Growing Plants for California
October 22, 2015 - Iím looking for the best plants for me. I have small kids so they would have to be safe. I would like them to be able to grow inside or outside. I would love for them to grow fast and reproduce fast.
view the full question and answer

How toxic are milkweed (Asclepias spp.)?
November 01, 2011 - 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?
view the full question and answer

Is Parthenocissus heptaphylla poisonous?
October 27, 2009 - Hi, I have a simple question for you, but I can't seem to find the answer to it. Is Parthenocissus heptaphylla toxic the way the VA creeper is? From what I've read, they're very similar in many way...
view the full question and answer

Fast-growing tree for horse arena in Southern California
July 06, 2011 - I live in Trabuco Canyon, CA, and we just lost an old Sycamore in our horse arena. I would like to replace it with some thing that is fast growing, and will be able to withstand life around horses, o...
view the full question and answer

Lantana induced rash
October 20, 2011 - What should I use for a rash caused by a Lantana scratch on my arm
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2015 Lady Bird Johnson Wildflower Center