This is the opposite of the ‘right plant in the right place’. It is something that horticultural professionals should neither promote nor tolerate when feral plants appear in landscapes that they are getting payed to maintain. This example looks like it is more relevant to the topic of ‘Fat Hedges’ from https://tonytomeo.wordpress.com/2018/06/06/horridculture-fat-hedges/ , but there is more to this feral pyracantha than that. Yes, it is shorn too frequently to bloom or produce colorful berries. Yes, it looks like an upside-down and halfway buried Christmas tree. Yes, it contributes nothing to the landscape. What is worst of all is that it does not even belong there. It was certainly not planted there on the edge of the curb. There are others nearby, but they happened to appear in spots where they could have actually been assets to the landscape if they had not also been shorn into this weird upside-down and halfway buried Christmas tree shape.
Pulling or at least cutting weeds is generally one of the responsibilities of maintenance ‘gardeners’. It might be acceptable or even preferred to leave a few feral plants if they happen to appear where they might be useful. Those that appear where they would be a problem must be removed. It really would not have been much work to pull this particular pyracantha if it had been done when it first appeared. Even if it had not been pulled right away, and gotten cut down by a weed whacker long enough to develop strongly attached roots, it could have been dug out while young with only a bit of effort.
Okay, so that is in the past now, just like all the other days, weeks, months and years that this feral pyracantha was not removed. Okay, so if for some reason known only the maintenance ‘gardener’ who likely charges significant fees for the maintenance of this landscape, this specimen is to be salvaged, should it not have been pruned back away from the curb? Of course! Although it is right on the curb, much of the growth could have been directed back away from the curb and over the bare embankment. That area is not used for anything anyway. The emptiness of the embankment is certainly no asset to the landscape. Empty pavement is an asset here.
A chain is only as strong as the weakest link. A driveway is only as wide as the narrowest part. All this asphalt pavement and concrete curb is expensive. It was probably worth it to get a nice wide driveway. However, the usable area is not as wide now as it was originally. The feral pyracantha that looks like an upside-down and halfway buried Christmas tree extends nearly four feet into it. That means that the usable space of the expensive driveway is nearly four feet narrower in that spot than it should be. Just think of all the expense that could have been saved if the driveway had been constructed four feet narrower than it had been!
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.