I apologize in advance. Although I spend a lot of time outdoors, am quite the nature lover, and have made some strides learning about birds, my knowledge of flora and fauna is woefully sparse. Now that I have retired, I hope to learn more, and feel very fortunate to have discovered this site. My question: Why are cherry blossom and magnolia trees not considered invasive species? (I love them, but wondered why they don't fit into the same category as Scotch Broom. My guesses: "Non-fruit-bearing" has something to do with it? Or perhaps, they are all over the city, but don't propagate without help from a gardener? Thank you!
This is more to the point. Broom propagates itself wildly without any outside intervention, as does Vinca (another major offender), Knotweed (Fallopia japonica and its relatives) and most other invasives for that matter. Hence, if one gardener plants an invasive and forgets about it, it takes over and has the potential to spread unchecked, often choking out native flora. Here in Ecuador, blackberries are considered a pernicious invasive threat, particularly on the Galapagos islands, and it's actually possible to get a job that consists solely of digging up and burning blackberry cane - it's a major threat to the archipelago's unique flora, and it's particularly invasive because the seeds are spread by birds. However, the chances of a Magnolia self-seeding in the PacNW is pretty much zilch - so although it's very popular, it's not an invasive. Same goes for flowering cherries. They're aliens, for certain, but they're not threats in any way to the natural ecosystems of the area - the same way that Hibiscus trees are down here; very popular in landscaping, with no chance of escape.
This is another serious, but often overlooked, problem with invasive species - the renaming of plants by those on the receiving end, and subsequent global spamming of those invasive names, which can be very offensive to those for whom the species is a local native. The correct English name for Cytisus scoparius is Common Broom.
