Ok, I bet you think this post will be about the human volunteers that come in so handy at many events. Au contraire. Let’s talk about that other biological volunteer, the plant that pops up where you didn’t plant it.
Volunteers come in many shapes and sizes and, yes, in a range of desirability as well. We have the volunteers that propagate and spread from plants on our own property, readily identified. There are those that show up from unknown origins but suspected transport is often birds. These may be native or non-native. And then there are, shudder/groan, those dreaded, unwelcome visitors that appear as bad actors on our individual State’s “Noxious or Invasive Weed List”.
Dealing with the Noxious or Invasive Weeds first, these we really don’t have a choice in options. Many states have a list of weeds that are mandated to be controlled. They are not welcome, they have proven to be invasive to the detriment of an existing plant or ecosystem and, sometimes, there is a zero tolerance with fines involved. I emphasize the need to pay attention to your individual State’s list because not all plants are invasive or noxious in all areas. A rather classic example of this is the Norway maple, Acer platanoides. This popular shade tree has been listed as “invasive, not banned” in Connecticut and “prohibited” in Massachusetts according to the USDA NRCS Plants Database. https://plants.usda.gov/core/profile?symbol=ACPL This site also has a list of federal and state lists for noxious weeds. But to tell you the truth, looking at some of the dates, I would google your state to be sure you get an up-to-date list. For instance, the USDA website has a list dated 2006 for Montana, but a quick google to mt.gov shows a current list dated February of 2017.
Many of these plants were introduced in the past as ornamentals or had the ability to thrive and grow quickly in harsh environments. They have since “escaped” captivity and has no trouble reproducing and surviving all by themselves. Unfortunately, in the case of those declared “invasive”, that ability proved to have negative results in its new home.
Some plants have “naturalized” and are not listed as noxious weeds. The white-leaf poplar, Populus alba, is an example. They make a good field tree where a grove is desirable. They do not make a good landscape plant where above ground space is limited and where there is a managed lawn.
Back to the more acceptable volunteers. At our place, we have a basic philosophical approach: unless it is identifiable as a listed noxious/invasive weed, it can stay until we determine (1) what it is, (2) if we like it and (3) if where it has set up camp is acceptable.
Interpretation of the criteria can produce lively discussions between my husband and I on defining “liking” and “acceptability of site”. He has a tendency to look far into the future as to whether or not the new addition to the property will be appropriate. I am much more inclined to take the “wait-and-see” approach since not all survive anyway.
Example: A box elder, Acer negundo, has volunteered in a garden spot in close proximity to an existing honeylocust, Gleditsia triachanthos. He keeps telling me there is no way a tree of that potential size will work there. MY contention is that I don’t think it is going to survive long term and I want to see how long it does survive. (Pretty sure a seed came in from a job we did in the past as this is in an area mulched with whole tree chips.)
I do like to leave plants until I have identified them. One volunteer my husband wanted me to pull has turned out to be a clove currant, Ribes aureum. Again, he keeps saying it won’t work long term where it is. Ok, it is a shrub with the capacity to get 8 ft by 8 ft and planted itself right next to (another) volunteer (who got there first), an elderberry (of as yet to be determined species) which also gets rather large. Both are fairly close to our house and close to ANOTHER volunteer, an oak-leaf mountain ash, Sorbus hybrida, a cross between the European mountain ash and the Swedish mountain ash, which is a tree with the capability of getting 30 ft tall and 20 ft wide. I just keep telling him this will give him ample opportunity to say “I TOLD you so!” in the future.
The clove currant has a lovely flower with the most gorgeous clove scent. The pollinators have already voted it the Best Newcomer this year. The elderberry had berries its first year (2017), which were a big hit with the birds. The mountain ash was a ladybeetle nursery last year in its first appearance hosting over 14 larvae. Transplanting is an option but I don’t want to chance losing any of these. After all, we can always move the deck.