Rent Shop Volunteer Join

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

Wednesday - March 25, 2009

From: Austin, TX
Region: Southwest
Topic: Trees
Title: Are hackberries harmful to other trees?
Answered by: Joe Marcus

QUESTION:

A neighbor warned me that a hackberry tree that naturally sprouted up recently will harm the roots of other trees nearby and that it is such a bad tree we should take it down before it gets too big. It is surrounded by mostly cedars and an oak. Do you thinks hackberries can do harm and are worthy of removing for that reason?

ANSWER:

Every plant that puts down roots in the earth compete in some way with its neighbors; some compete more aggressively than others.  The rhizosphere, that is, the soil where roots grow, can be thought of quite accurately (if not a bit simplistically) as a war zone.  Plants, animals, fungi and microorganisms living within the rhizosphere continually struggle with one another for their share of the resources available there.

Many trees and other plants interfere with their competition through one of a multitude of processes known collectively as allelopathy.  Allelopathy typically involves living or dead and decaying plant parts exuding, volatilizing or leaching chemical compounds that are inhibitory or harmful to nearby plants.

Hackberry trees, Celtis spp. are known to inhibit the growth of competing plants through allelopathic processes.  The mechanism used by hackberries involves the release of a witch's brew of chemicals known as phenolic phytotoxins leaching from fallen, decaying leaves.  The leachates from rotting hackberry leaves have been shown to inhibit the germination of seeds and the development of seedlings.  So yes, hackberry can do harm to nearby plants, though it is unclear if it has any effect at all on established plants such as trees, shrubs or even mature perennials. 

Ashe juniper, which is probably the cedar your mentioned in your question, and oaks are also known to be allelopathic.  Few plant species will thrive beneath the canopy of Ashe juniper.  If there are any sycamores, pecans or walnuts in your garden, they're also waging chemical warfare on one another.  Lest you come to think of these trees as "bad plants," you should know that as time goes on we will certainly come to learn that many, if not all, plants employ chemical defenses (and offenses) in one form or another.

As landscape plants, hackberries are not without other problems.  They're messier than most other trees, tend to be short-lived, are prone to breaking in storms and don't often make particularly handsome specimens.  On the other hand, hackberries are extremely important sources of food for wildlife.  Many birds, mammals and some butterflies depend on hackberries for their survival.

On balance. hackberries definitely play an important role and have a place in nature and maybe even in peripheral areas of your landscape.  They are probably best left out of more prominent parts of your garden, though.

 

 

More Trees Questions

Sweet cherry tree for New Mexico
January 23, 2013 - What is the best kind of sweet cherry tree to plant in Santa Fe, NM? I have apple, apricot, peach and pear. Would like cherry unless it is a bad idea.
view the full question and answer

Pin Oak Dropping Leaves Early
December 17, 2015 - I have a large pin oak that's losing it's leaves at this time. Is this too early? I have been watering the tree during the hot, dry weather and overall the tree looks healthy and has a good crop of ...
view the full question and answer

How to tell the girls from the boys in wax myrtles (Morella cerifera)
May 14, 2010 - How would I be able to identify whether my wax myrtles are male or female plants? I was given two plants last fall (that came from a family members back yard) and the person who gave them to me didn'...
view the full question and answer

Leaves falling early from red oaks.
October 08, 2007 - The leaves on my Texas red oaks are dropping off prematurely. This usually doesn't happen until late November/early December. I'm wondering if it has something to do with our wet summer, or if I sho...
view the full question and answer

Names of native plants in Garland, Texas
October 31, 2008 - We are building a new Assisted Living & Memory Care community in Garland Texas. We typically name the different floor plans after trees, plants or flowers indigenous or native to the area. Can you pr...
view the full question and answer

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