Horned Poppy or Rugosa Rose: Which One is Invasive in Massachusetts?

Now here are a couple of alluring, exotic lovelies - and can't you just hear the hot whir of seamy search engines drawn to that opening like ants to a picnic?  They are certainly attractive plants, among their other qualities, and are among the estimated 10,000 plant and animal species introduced to North America since European settlement.  Unlike the overwhelming majority of introduced species, the behavior of these two made them candidates for listing as Invasive in the Commonwealth of Massachusetts.  Both were assessed by the Massachusetts Invasive Plant Advisory Group or MIPAG, on which I had the honor of serving for nearly 6 years.  Only one made the cut.

Yellow Horn Poppy or Sea Rocket (Glaucium flavum, above) has been in this country for hundreds of years.  Thomas Jefferson planted it at Monticello.  Native to Mediterranean Central Europe and the Black Sea region, Glaucium flavum in New England is established south of Cape Cod along Buzzards Bay, in Rhode Island, and (historically) in Connecticut.  It is also present as far south as Virginia, along the West Coast, and in several other states including Colorado and Oklahoma.  It has likely been repeatedly introduced in contaminated ship ballast and has been documented escaping from ornamental plantings.

Full disclosure compels me to reveal that I had more than a nominal role in getting documentation on Glaucium flavum in Massachusetts habitats for its evaluation.  The photo above was taken this June at the family home in Wareham on the shores of Buzzard's Bay.   If you look at the page for this species in the Invasive Plant Atlas of New England, you will see a number of photographs taken at my invitation by researchers John Silander, Leslie Mehrhoff and their UCONN students at the beach at "Windrock".  I asked them to visit because MIPAG was having trouble finding documented field evidence of the behavior of Glaucium flavum in Massachusetts habitats and we've been living with the stuff for decades.  My mother, in fact, recalls when it first appeared on the cobble shore after one of the Hurricanes in the 1960s.  I did not have a particular animus toward this species, but did feel it warranted additional, non-anecdotal evidence for the group's consideration.

We reviewed Glaucium flavum in MIPAG's first phase of invasive species assessment.  It was in the same company as plants generally regarded as "known thugs" even by members of the group who were leaders in the nursery and landscaping industry.  As I have previously written, MIPAG developed assessment criteria in collaboration with a wide group of stakeholders in the public, non-profit and private sectors and was determined to put every candidate species through the same transparent process before calling it invasive.  Here are the criteria:

For a species to be designated as "INVASIVE", "LIKELY INVASIVE" or "POTENTIALLY INVASIVE" it must meet certain base criteria (#1-4 below). The species must:

(1) Be non-indigenous to Massachusetts, (2) Have the biologic potential for rapid and widespread distribution and establishment in minimally managed habitats, (3) Have the biologic potential for dispersing over spacial gaps away from site of introduction and (4) Have the biologic potential for existing in high numbers away from intensively managed artificial habitats.

If a species does not meet all four of the previous criteria, stop here.  The species cannot be listed at this time.  If a species meets all 4, go on to #5.

(5) Be naturalized in Massachusetts (persists without cultivation in Massachusetts).

If a species meets criteria 1-4 and criterion 5, it may be considered "INVASIVE" or "LIKELY INVASIVE" in Massachusetts.  Go on to criteria 6-9. 

If it does not meet criterion 5, it may be considered "POTENTIALLY INVASIVE" if it meets criteria 13-15.

(6)  Be widespread in Massachusetts, or at least common in a region or habitat type(s) in the State, (7) Have many occurrences of numerous individuals in Massachusetts that have high numbers of individuals forming dense stands in minimally managed habitats, (8) Be able to out-compete other species in the same natural plant community and (9) have the potential for rapid growth, high seed or propagule production and dissemination, and establishment in natural plant communities.

If a species meets the initial 5 criteria and Criteria 6-9 it may be considered an "INVASIVE" species in Massachusetts.

If a species meets the initial 5 criteria, but does not meet all of Criteria 6-9 at this time, it may be considered a "LIKELY INVASIVE" species in Massachusetts if in addition it meets at least one of the following three Criteria (#10-12).

(10)  Have at least one occurrence in Massachusetts that has high numbers of individuals forming dense stands in minimally managed habitats, (11) Have the potential, based on its biology and its colonization history in the Northeast or elsewhere, to become Invasive in Massachusetts and (12) Be acknowledged to be Invasive in nearby states but its status in Massachusetts is unknown or unclear.  This may result from lack of field experience with the species or from difficulty in species determination or taxonomy.

If a species meets the basic criteria for invasiveness (Criteria 1-4) but is not naturalized in Massachusetts (Criterion 5), the species may be considered "POTENTIALLY INVASIVE" in Massachusetts in it meets the following three criteria (#13-15):

(13)  The species, if it become naturalized in Massachusetts, based on its biology and biological potential, would pose an imminent threat to the biodiversity of Massachusetts, and (14) Its naturalization in Massachusetts is anticipated, and (15) the species has a documented history of invasiveness in other areas of the Northeast.

A lot of data and documentation went into answering these questions, and in the end the assessment determined Glaucium flavum met the criteria for listing as Invasive in Massachusetts.  Although it was more geographically restricted than some of the other invasive plants we assessed, it still met Criteria 6-9.  Massachusetts is the first of the fifteen states where there are records of this species in minimally managed habitats to declare it Invasive, and it is now on the list of regulated species prohibited from introduction, importation or sale in the Commonwealth.

The other beauty at the top of this post, the enticing Rosa rugosa, went through the same assessment but in Phase II.  I took this photograph about three feet from the Glaucium flavum specimen with which it is paired in this post.  It is a widely planted urban and coastal plant and occurs in many of the same minimally managed habitats as Glaucium flavum.   MIPAG decided not to list this plant as invasive, offering the explanation that

"Listing it as Invasive or Likely Invasive does not accurately reflect all the properties of this plant; there are no data at this time to suggest that this species is disruptive to native plant habitats in Massachusetts."

Now this is not a kiss and tell post, nor am I interested in undermining what I believe is the best collaborative assessment and most transparent criteria used to determine invasiveness in the United States today.  The process and the criteria, however, were new when applied to these species and I wonder whether my colleagues still on MIPAG today would consider Glaucium flavum or Rosa rugosa in the same light if reviewed a second time.  In both cases, the hardest questions to answer were whether the species were out-competing native species in minimally managed habitats.  It has been several years, but I can't recall that the evidence was overwhelmingly convincing that Glaucium flavum was doing this.  Nor am I convinced today that Rosa rugosa does not satisfy Criteria 1-5, making it at least a candidate for "POTENTIALLY INVASIVE" as it is listed in Connecticut (which uses similar but not identical criteria to Massachusetts for assessment of invasive species).

MIPAG's work is not finished, however, and species that have already been reviewed may be reassessed as new documentation becomes available.  I do not feel there is a burning need to put that on a fast track with either of these species. As invasives go, they are far less disruptive than others that come immediately to mind.  But even a scientific assessment tool is only as good as the data that goes into it, and some of the measures in the criteria are more qualitative than others.  The important thing is that there is a transparent process in place and that it is able to adapt at least as well as the species under assessment.

Comments

[GreenmanTim]

Thanks for catching that, Vertalio. The comma was right, now corrected to read 10,000. And I agree, damn the grass.

[Vertalio]

Um, that 10,0000...is that 10,000, or 100,000? Comma wrong, or period?

And, lawns? I let creeping jenny and blue bugels and violets and false heather and hawkweed expand there, because they grow three inches tall and stop. Damn the grass, anyway.

[GreenmanTim]

My friend Tim Simmons at Mass DFW used to cock a bushy eyebrow at me and ask if our research was going to appear in the non-existant "Journal of Minimally Managed Habitat." Folks on the MIPAG didn't care for "natural" as a modifier, but nor did we wish to be regulating dandilions that are only a problem in lawns. My lawn, mind youy, might well qualify as minimally managed at this time of year...

[Jenn]

Great post!

When I worked on a project that used a slightly modified version of this risk assessment in 2006, specifically for the island of Nantucket, both of these species had "Yes" across the board for 1-9 (complete species list is at http://efg.cs.umb.edu/nantucket ).

We has some issues with the vagaries of such phrases as "minimally managed habitat" and "dense stands" so erred on the conservative side. But still, because both of these species do well in coastal habitats (salt tolerant), they are doing well in established wild populations on the island. Rosa rugosa is still cultivated there, of course, and scarily grows 10 feet high (I have never seen it like that on the mainland, even when planted).

Note that the assessment says the species must "Be able to out-compete" other species, it does not require that explicit evidence be provided that it is outcompeting...perhaps because we do not realistically have the resources to do that kind of research for every species evaluated?