Soul Scientist

Romans 12:8a If someone has the gift of speaking words of comfort and help, he should speak.

Proverbs 25:11 A word fitly spoken is like apples of gold in a setting of silver.

Have you happened to notice that nothing will grow under the leaf canopy of a black walnut tree? No matter how much fertilizer you put on or how many times you reseed, there’s nothing there except bare ground and the leaf and nut residue from the tree itself. There’s not even that much insect, mole, or vole activity under these trees either.

Have you noticed that the grass or other plants will slowly resume growth at the outer edge of where the leaves extend from a black walnut tree? Then they get thicker, stronger, and denser further and further out from the tree, as does the insect and small ground animal activity.

This phenomenon is called allelopathy.

Black walnut and other trees including some maples, pines, and eucalyptus give off chemicals from their roots, bark, fruit, or leaves that are toxic or inhibitory to other plants. Other plants including sumac, rhododendron, and forsythia do the same which is why the ground underneath them is usually bare soil except for what has come from the plant itself. These chemicals give allelopathic plants advantage over other plants in survival and reproduction by effectively removing their competitors from their little part of the world, currently and in the future.

For even if a black walnut tree or forsythia bush has been cut down and removed from an area, it still takes time and diligent work for other plants to grow, much less thrive, in this area. The allelopathic chemicals can persist in soil for years, even if they are not being actively made by a growing plant. The chemicals bind with soil clays and soil organic matter (SOM) in ways resistant to removal both by water movement and breakdown by microbial or chemical pathways. Moreover, their innate chemical structure is complex which also makes them resistant to natural pathways of decay and removal from soil. As importantly, the secondary or tertiary products which the primary allelopathic chemicals degrade to can be as toxic (or more so) than the original chemicals. These products can also be very persistent in the environment as well.

Since SOM, along with some clays, is so small, the products can travel with the soil in water moving in a stream or lake or over the soil surface during flooding. Thus, these chemicals can be transported and deposited elsewhere and have the same effect (though not as strong) as they did in their place of origin. Having said all that, how appropriate that the Greek root words for allelopathy are allelo “of each other” and pathos “suffering”.¹

Another interesting point about allelopathic chemicals is that they are not inhibitory to other plants of the same species. In other words, the presence of a black walnut tree will not inhibit or prevent the germination and growth of another black walnut tree. However, the chemicals from one allelopathic species will inhibit the germination and growth of a different allelopathic species.

Not all allelopathic interactions are toxic or inhibitory between species. Some are actually mutually beneficial by one plant species supplying another with needed nutrients or enhancing soil microbial growth. However, at this point in our limited knowledge of the many and varied relationships between plant species, most allelopathic interactions are not mutually beneficial.

In nature, often one species flourishes while another suffers.

Unfortunately, I often see this relationship mirrored in my own life.

Far more than I’d like to admit, I am in an allelopathic relationship with people in my life. My natural inclination is emitting words, actions, and responses which inhibit others’ pursuit of Christ. My words often exude selfishness, arrogance, and greed instead of love, grace, and mercy (see Psalm 59:12). And all of my toxic responses can be even more hurtful than a black walnut tree to the grass in my front yard. To me, the presence of allelopathic species in soil remind me of this verse: The good person out of the good treasure of his heart produces good, and the evil person out of his evil treasure produces evil, for out of the abundance of the heart his mouth speaks (Luke 6:45).

I can’t take back words; I can only ask for forgiveness (see 1 John 1:9).

I can’t retract responses; I can only pray for God to use them for good (see Genesis 50:20).

I can’t change choices; I can only make different ones afterwards (see Romans 7:15).

Instead, I can pray for those words, responses, and choices yet to come to be ones which display Christ, not me (see Proverbs 22:5). As importantly, I can fervently pray for all those hurt by allelopathic me and look with expectation for His work in their lives (see James 5:16). 

Only my Good Gardener God is powerful enough to overcome the guilt, shame, regret, and pain of all of my toxic words that have spewed out into others’ lives in the past and still try their best to seep up from deep inside my heart yet today (see Genesis 18:14).

Often, the closest people to me in my life are the most likely recipients of my toxic words.

Their closeness to God and to me can be inhibited by my toxic responses. Just as bad, my lack of words and compassion for others in their times of need can stunt their faith or return to Christ for health and life (see Hosea 6:1). I’m learning those times when I only see myself are often those times when I most need to be seeing others in their pain (see Luke 15:11-32, specifically v. 20).

All of us have the natural tendency to operate out of the pain in us, rather than the Jesus in us.

Just like Hagar in the desert, we all have times we need to be seen by others like Hagar was by her El Roi, the God Who sees me (see Genesis chapter 16). Also, like her, those times when I’m most needing people close in my life is when I’m most likely to spew evil out into their lives from fear, lack of repentance, and guilt in my life.

So, why am I surprised when others do the same to me?

Times like these are especially true to the saying of “two wrongs don’t make a right.” I can react to them with more suffering as expected from allelopathic me. Or I can choose to respond to their suffering by exuding the gift of His mercy made new every morning (see Lamentations 3:22-23). If I choose faith over fear, I can give off nourishing bits of the grace that keeps me from doing the same to them (see 1 Corinthians 15:10).

I’m learning that in these choices, my own allelopathic life is slowly being transformed into a fresh newness (see Romans 12:1-2).

A newness where words can be those apples of gold in settings of silver (Proverbs 25:11). A freshness where opportunities for bringing comfort and help do abound right there in the straight paths He sets before me as I trust Him (see Romans 12:8a and Proverbs 3:5-6).

God can change naturally toxic me from the ground up. And He can do the same for you, too.

God can and He will, if we ask and submit to His good cultivation in the garden of our hearts and lives. God alone can replace toxic words, actions, and reactions with helpful words, choices, and responses. God alone is strong enough to remove those persistent tendencies towards evil and bring good in their place.

God alone can make all of us live a life like that described in Psalm 1:3 CEB They are like a tree replanted by streams of water, which bears fruit at just the right time and whose leaves don’t fade. Whatever they do succeeds.

written by and copyrighted to Beth Madison, Ph.D., 2025

This was an excerpt from my book Good Seed which will hopefully be released in 2028. If you want to guarantee you don’t miss any further excerpts or announcements, please use the sign up for the blog here button. I’d love for you to join us in this journey of grace to our Good God. And please make sure and bring a friend or two along for the ride, too!