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 - March 03, 2007

From: Tyler, TX
Region: Southwest
Topic: Best of Smarty, General Botany, Poisonous Plants
Title: Native plants that will grow under alleopathic black walnut
Answered by: Nan Hampton

QUESTION:

I have a large, beautiful black walnut tree in my yard and have trouble growing the annuals, begonia, impatients, etc., that I have always grown. They don't do well in the ground and I have resorted to putting them in pots in order to have some color in that shady area. Any suggestions as to what soil amendment I can use so they can be planted in the ground?

ANSWER:

Your black walnut tree (Juglans nigra) is defending its space—that's why you are having trouble getting any other plants to grow underneath it. With this defense mechanism, called allelopathy, the tree makes and releases a chemical called juglone that adversely affects many other (but not all) plants. Juglone can be found in all parts of the black walnut tree. If the roots of another plant come within 1/2 inch of the walnuts roots, they can absorb the juglone and sicken and die. Also, walnut leaf litter and walnut fruit on the ground leach juglone into the soil.

Virginia Extension Service has an excellent discussion of the black walnut and its allelopathic effects. Additionally, the article lists common plants that are affected by the juglone of the walnut. There is also a list of plants that will grow near the black walnut. Here are a few attractive native plants that will grow underneath your tree in Tyler:

Black-eyed susan (Rudbeckia hirta)
Pink evening primrose (Oenothera speciosa)
Cardinal flower (Lobelia cardinalis)
Virginia creeper (Parthenocissus quinquefolia)
Inland sea oats (Chasmanthium latifolium)

By the way, allelopathy is one of the reasons some invasive plants, such as spotted knapweed (Centaurea biebersteinii), are so successful.

 

More Poisonous Plants Questions

Toxicity of Fan Tex Ash tree to horses
July 22, 2012 - Is the Fan Tex Ash tree toxic to horses?
view the full question and answer

Getting rid of poison ivy
May 08, 2009 - Dear Mr Smarty Plants, Likewise I also have a shady area in my yard with overgrowth of poison ivy. It borders a small duck pond and we have a Golden Retriever. I too would like to plant soon afterward...
view the full question and answer

Plant identification of tree in North Carolina
September 07, 2011 - I live in North Carolina have found a tree on our property that has thorny branches and round fruit (perfectly round) with a fuzzy outer layer that starts out green but then turns yellow. The inside r...
view the full question and answer

Non Toxic Fruit Plants
April 03, 2015 - I am trying to plant on my backyard. My dog spends about 8 hours a day outdoors and I am afraid she will be poisoned. I am overwhelmed by the information of toxic trees\plants for dogs. However, I ju...
view the full question and answer

Identification of possible toxic plant in Austin, TX
June 20, 2014 - When we hike with our dogs along Turkey Creek in Austin, they seem to make a bee line to a small green leafy plant when they find it along the trail and eat a few leaves of it. We assume it's not dan...
view the full question and answer

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