What characterizes a codominant stem in trees?

A codominant stem in trees is characterized by forked stems that arise from a common union. This condition occurs when two or more stems grow closely together, sharing the same base or trunk, leading to a forked appearance. Codominant stems can create structural vulnerabilities for the tree because the stems may compete for resources and can lead to issues with stability, especially during high winds or heavy snowfall, where the union may fail.

The other options describe different growth patterns. For instance, stems growing from separate root systems would indicate individual trees rather than stems of the same tree. A single stem emerging from the ground describes a typical tree structure with a single trunk, while independent stems not being related suggests isolation, which does not apply to the concept of codominance. Therefore, the defining feature of codominant stems clearly aligns with the presence of multiple stems originating from the same base.