Dogs and humans have been in a symbiotic relationship longer than history can document. Dogs naturally became more domesticated as humans did, and have been more or less selectively bred for a few thousand years.

Dingos are different. No one knows for certain how domesticated they were when they first came to Australia. They probably had been domesticated enough to come on boats with the first humans to migrate to Australia. After arriving in Australia, they became feral, although still symbiotically migrating with humans. They are now considered a native species of Australia.

Many species of plants have lived symbiotically with humans as well. As long as humans have been living with dogs, they have been domesticating and breeding plants. As plants were more extensively bred, they became more dependent on humans for their perpetuation. Some are so overly bred that they are sterile and unable to perpetuate without human intervention to propagate them vegetatively. Others, although unnaturally productive in regard to what humans want from them, are too weak or otherwise inferior to survive in the wild.

However, there are some extensively bred plants that escape their domestic lifestyles, and perpetuate feral descendants who retain some of the domestic characteristics of their extensively bred ancestors. They are not quite like naturalized plants that were merely imported in a more or less natural state from other regions, or those that naturalize and revert to a natural state. Characteristically, they are between wild plants and extensively bred and selected domestic plants. They have developed their own stable but feral lineage that can perpetuate in the wild.

For example, the purple leaf plum has been developed as an ornamental tree for a very long time. Several vegetatively propagated cultivars are now available. The ancestors were likely discovered as mutants with darker bronzed foliage. These primitive mutants were more or less genetically stable, and were likely able to perpetuate naturally. It is difficult to say for certain. From these ancestors, seedlings with even darker foliage were selected, and bred to find more seedlings with even darker foliage, and so on. Because of this selective breeding, purple leaf plum trees grown as domesticated ornamental trees now have darker foliage they would naturally in the wild. They are propagated vegetatively because some are so overly bred that they are sterile, and seedlings from those that can produce viable seed would be likely be more genetically stable, and therefore less genetically ‘developed’. This is why feral seedlings from purple leaf plums that can produce viable seed are not as dark purplish bronze as their parents. Seedlings from the seedling trees are even lighter bronze. They may never be completely green, but they will not be dark purplish bronze either. They are feral purple leaf plums, like dingoes.