Black Walnut guild

By Dave Whitinger (dave) on June 10, 2010

Walnuts are toxic to most plants, but some plants will actually grow quite well with walnuts.

Plants are said to be allelopathic when they produce chemicals that influence the growth, survival and reproduction of other organisms. Black Walnuts produce the chemical juglone, which is toxic or growth-stunting to most other plants. The production of juglone is why the genus for Black Walnut is Juglans.

But, we all like to grow Black Walnuts (especially if we already have some on our property) so it seems good to try to find other plants that will indeed grow around them.

Hackberry/Sugarberry (Celtis) are medium-sized trees that produce a small fruit "reminiscent of a date." Hackberries are themselves allelopathic. According to wildflower.org, "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." [Source] I believe in Texas or other areas of the south I would grow Celtis laevigata.

Currant berries are often found growing under and around Black Walnuts, especially when hackberries are also present. [Gaia's Garden]

Elaeagnus is prescribed for nitrogen fixation. The goumi bush (Elaeagnus multiflora) grows berries fit for consumption by man and beast. Red Bud (Cercis ssp) are legumes that are resistant to juglone and would be good for this guild.

Alliums, beans, carrots, corn, and cucurbits, according to http://wihort.uwex.edu/landscape/juglone.htm

Mulberries produce edible fruit and are often found growing alongside them.

One thing that I find interesting and I want to study further on the subject, is mulberry's relationship to Black Walnuts. In my own bottom land (which is completely virgin land, never harvested for timber) I have many black walnuts and almost all of them have mulberries growing next to them. There is talk out there that mulberry is a bridge between the walnuts and other plants, protecting the other plants from the juglone chemical.

Of all plants, the solanaceae (nightshade) family is traditionally known as the most sensitive to juglone. Yet, Gaia's Garden prescribes solanaceae plants in this guild. Especially tomatoes and peppers. I'm not so sure of that but perhaps on the other side of a mulberry you'd be successful. I have lots of wild solanaceaes growing around here and I've never seen any near my walnuts.

My walnut groves are very old and very established. I have a goal to get an identification on all the plants, shrubs, vines and trees that are already growing in these naturally occurring guilds.

This is a useful thread about walnut guilds.

Update: I went for a walk this afternoon through part of the bottom land and took pictures of some of the various communities that are growing around my walnuts.

Celtis laevigata (Sugarberry):

Note here that this Celtis is growing together with a walnut. They have inosculated into each other.

Another sugarberry specimen. This one is gigantic and is right next to an equally sized walnut. Note the massive grape vine growing into it, and pokeweed growing around it. Carolina Cherry Laurel is growing on the far side.

The photo below shows the guild that the sugarberry above is a part of. The sugarberry is on the left and the walnut is on the right. Note the heavy grape foliage in the sugarberry. Cherry laurel on the left. You can also see the trunk of a river birch directly between the two main trees. I am facing west when I took this photo.

Here's the floor of that guild. Pardon the roll of fencing. One thing to note is that there is a river birch growing directly between the walnut and the sugarberry. You can see it on the right side.

Moving on, an Elm (probably Ulmus americana). Thanks to knoxred for identifying it for me.

This short ground covering minty-smelling thing is growing all underneath the above Elm tree:

Below shows Osage Orange (Maclura pomifera), Walnut, and Carolina Cherry Laurel (Prunus caroliniana; related to plums, pears, etc) all packed in together in a nice happy community of plants.

I was surprised to see this cottonwood growing near the walnuts.

I believe the below shows a mulberry. There are a lot of these growing amongst the walnuts.

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Comments and discussion:

Subject Thread Starter Last Reply Replies

Really interesting stuff! knoxred Sep 29, 2010 1:48 PM 15

Great article stormyla Sep 28, 2010 9:18 PM 16

A subject close to my heart CeeDub Jul 19, 2010 11:48 PM 1

How large an area is toxic paulgrow Jun 11, 2010 8:38 AM 3

Interesting Ridesredmule Jun 11, 2010 8:27 AM 0