En EspaŅol

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
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

Sunday - March 24, 2013

From: Dallas, TX
Region: Southwest
Topic: Compost and Mulch, Diseases and Disorders, Trees
Title: Allelopathy of American elms from Dallas
Answered by: Barbara Medford

QUESTION:

Are American elms at all allelopathic?

ANSWER:

There are four members of the genus Ulmus (elm) native to Texas and in or near Dallas County:

Ulmus alata (Winged elm)

Ulmus americana (American elm)

Ulmus crassifolia (Cedar elm)

Ulmus rubra (Slippery elm)

Black walnut isn't the only tree that produces juglone. This chemical is also secreted in smaller amounts by English walnut, hickory and pecan trees.Other trees with allelopathic properties include tree-of-heaven, sugar maple, hackberry, American sycamore, American elm, southern wax myrtle, cottonwood, black cherry, sassafras, red oak and black locust.

Certainly, in our experience, members of the Juglandaceae family (most familiar - walnuts, pecans) are the most prominent examples of allelopathy, but the American elm is definitely included as being able to deal with competing plants with chemicals. Please note that it is difficult to impossible to grow anything under any tree, including grass, because of the needs of the tree roots for moisture and nutrients from the soil and because of the shade from the tree. Here in Texas, we would vote for the trees and spread mulch under the shade of the tree. See our How-To Article Under Cover with Mulch.

 

From the Image Gallery


Winged elm
Ulmus alata

American elm
Ulmus americana

Cedar elm
Ulmus crassifolia

Slippery elm
Ulmus rubra

More Trees Questions

Fast growing native hedges for Sachse, TX
March 30, 2007 - I just bought a house in Sachse, Tx and want to plant a privacy hedge. It will be about 220' long and I want it to grow to at least 10'-12' high. I also want it to be fast growing and be evergree...
view the full question and answer

Possible reasons for early leaf drop of post oaks in Austin
October 27, 2004 - I have a post oak tree in my back yard that has been losing its leaves since mid-September. This is my first year in the house, and I am surprised that the tree would lose its leaves while the temper...
view the full question and answer

Plant barrier to block view and noise of Florida Turnpike
August 05, 2009 - I live in Port St Lucie FL and my development backs to Florida turnpike. We want to plant to block noise and view. Any suggestions? thank you
view the full question and answer

Young Bur Oak not Flourishing in Texas
November 06, 2014 - We have a bur oak in our SW Travis County lawn in Texas, planted about 3 years ago as a 6-7' tree. It is now about 12' but has not "flourished". It has put out virtually no horizontal branches, an...
view the full question and answer

Propagation of Mexican olive in Luling, TX
August 04, 2009 - Mr. Smarty Plants: we live in Luling, just south of Austin and have a 4 year old Mexican Olive tree; question: how do we propagate this 'hard to find' tree? Thank you so much.
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2015 Lady Bird Johnson Wildflower Center