---
title: Codominant Stems: Two Trunks, One Weak Union
url: https://battleborntreeservice.com/glossary/codominant-stems/
business: Battle Born Tree Service
address: 6301 US Highway 50 East, Carson City, NV 89701
phone: 775.232.8243
hours: Office Monday-Friday 8:30 am-5:00 pm; phones answered seven days a week; 24-hour emergency service
credentials: ISA Certified Arborist WE-11728A on staff; Nevada Business License # 20131580674; fully insured
type: Tree service (removal, crane work, pruning, stump grinding, defensible space, snow removal, firewood)
---

- [Home](https://battleborntreeservice.com/)
- [Arborist glossary](https://battleborntreeservice.com/glossary/)
- Codominant stems

# What are codominant stems?

Codominant stems are two or more trunks of about the same size that grow out of the same point, so neither one is the leader. The fork where they meet is often weak, particularly when bark gets caught between them.

## How to recognise them

Look for a V or a U shape in the trunk. A U-shaped union with a clear gap between the stems is usually stronger than a tight V, because a V leaves no room for the stems to grow side by side. A tight V often traps [included bark](https://battleborntreeservice.com/glossary/included-bark/) and may show a seam or crack running into the fork. Stems that lean away from each other put extra load on the union.

Not every fork is a problem. A tree that has been forked since it was young, with stems that are much different in size, can be perfectly sound. What matters is how tight the union is and whether it shows cracks, decay or movement.

## Why it matters in Northern Nevada

Siberian elm, silver maple, honeylocust and many ash trees are known for forking, and each is common on older Nevada lots. See [Siberian elm](https://battleborntreeservice.com/tree-guide/siberian-elm/) and [silver maple](https://battleborntreeservice.com/tree-guide/silver-maple/). In Washoe Zephyr winds and in heavy wet spring snow, one stem of a fork may peel away from the other. Local homes are old enough, with about half of the homes in Carson City built before 1980, that many of these trees are now very large.

A split stem does not give much warning, and no one can promise a fork is safe. What an arborist can do is judge how likely a failure is and what it would hit.

## What an arborist does about it

Options run from pruning to slow one stem, to installing support through [cabling and bracing](https://battleborntreeservice.com/tree-services/cabling-bracing/), to removing one stem or the whole tree when the fork stands over a house, car or play area. The choice follows the size of the tree, the state of the union and the target below. On a young tree the same problem is solved cheaply by choosing a [central leader](https://battleborntreeservice.com/glossary/central-leader/) and cutting back the rival.

### Sources

- [International Society of Arboriculture, Trees Are Good: Recognizing Tree Risk (brochure)](https://www.treesaregood.org/Portals/0/TreesAreGood_Recognizing%20Tree%20Risk_0721.pdf) (read October 17, 2026)
- [U.S. Census Bureau: American Community Survey 2020-2024 5-year estimates](https://api.census.gov/data/2024/acs/acs5) (retrieved October 1, 2026)

### Talk to the office

[775.232.8243](tel:775.232.8243)

| Monday to Friday | 8:30 am - 5:00 pm |
|---|---|
| Saturday and Sunday | Office closed, phones answered |

Phones answered seven days a week. 24-hour emergency service.

[Free estimate](#quote)

### Keep reading

- [Arborist glossary](https://battleborntreeservice.com/glossary/)
- [Cabling and bracing: when it saves a tree](https://battleborntreeservice.com/guides/tree-cabling-bracing-explained/)
- [Warning signs before a tree fails](https://battleborntreeservice.com/guides/warning-signs-tree-failure/)
- [Siberian elms: the tree on every old Nevada lot](https://battleborntreeservice.com/guides/siberian-elms-old-nevada-lots/)

## See also

[Included bark](https://battleborntreeservice.com/glossary/included-bark/) [Central leader](https://battleborntreeservice.com/glossary/central-leader/) [Branch bark ridge](https://battleborntreeservice.com/glossary/branch-bark-ridge/)

## Read it in context

[Young trees in new subdivisions: the first ten years](https://battleborntreeservice.com/guides/young-tree-care-new-subdivisions/) [Tree risk assessment: what an arborist checks](https://battleborntreeservice.com/guides/tree-risk-assessment-what-arborists-check/)