Which of the following is NOT a characteristic used to identify trees?

Identifying trees involves analyzing various characteristics that can distinguish one species from another. Seed color, while it might vary among some species, is not a reliable characteristic for tree identification. This is primarily because seeds are often not readily visible or accessible for examination in live trees, and they can also be influenced by environmental factors or developmental stages.

On the other hand, growth habit refers to the overall shape and structure of the tree, which is highly useful for identification. Leaf scars, the marks left on branches where leaves have fallen off, provide distinct markers for species identification as the patterns can differ significantly between species. Similarly, flower structure is critical for identification because the morphology of flowers can be highly specific to certain species, offering clear traits that can be documented and used in distinguishing one tree from another.

Thus, seed color is typically not a characteristic used for identifying trees, making it the correct choice in this instance.