I’m fascinated by words, their sounds, their rhythms, their meanings. By semantics. Mostly I try not to be pedantic about words, but when the subject is “native” plants, I have to be.
It’s a word and concept that comes up all the time for us botanerds. Like asking if the newborn baby is a girl or a boy, nativity is where our understanding and appreciation of a plant starts.
But why? Why do we care, and what does it really mean, anyway?
Merriam-Webster defines “native” as “living or growing naturally in a particular region”. The USDA offers a more specific definition:
A plant that is a part of the balance of nature that has developed over hundreds or thousands of years in a particular region or ecosystem. Note: The word native should always be used with a geographic qualifier (that is, native to New England [for example]). Only plants found in this country before European settlement are considered to be native to the United States.*1 [emphasis mine]
In an online forum the topic recently came up, with respect to wood poppy (Stylophorum diphyllum, pictured above). Have a look at the USDA PLANTS Database distribution map for it:
The map implies that wood poppy is native to Maryland. Now have a look at the county-level map (same page, zoomed in):
This map shows wood poppy present somewhere in the state of Maryland (the light green color means that there are no county-level records). Note that other than in Maryland, there are only two locations east of the Appalachians where wood poppy is present: southeastern Pennsylvania and the District of Columbia. Considering the rest of the distribution, it doesn’t really make sense that there are “naturally occurring” populations of this species outside the mid-west.
Various sources I’ve checked agree that wood poppy is not native to Maryland. According to Alan Weakley, wood poppy is found in
Moist forests over calcareous rocks (such as limestone). Mar-Jun. S. QU, w. PA, s. MI, and WI, south to sw. VA, e. TN, nw. GA, sc. TN, and AR; introduced elsewhere from horticultural use. [= C, F, FNA, G, K, Mo, Pa, S, Va, W, WV] *2 [emphasis mine]
This is not to say that the USDA PLANTS Database is untrustworthy. It’s an excellent source of good information. My point here is that without the right qualifier, it’s useless to ask if a plant is native. In this example, it’s correct to say that S. diphyllum is native to North America, and it’s correct to say that it’s native to the lower 48 states, but neither of these statements implies that the species is native in every wild place it’s found.
Since wood poppy is not native to Maryland, but is found growing wild here, we need a word other than “native” to describe it. “Alien” would be technically correct but that word is loaded with negative connotations. The correct term is naturalized.
Getting back to that idea of geographic qualifiers, it’s possible to go a little crazy when you’re trying to decide if something is native. Consider Baptisia australis (wild blue indigo), which has a scattered distribution in the eastern US. In Maryland it is known in only a few locations along the Potomac River, including the Potomac Gorge. So if I were being utterly ecologically correct, I wouldn’t grow it in my garden, because my garden isn’t in the Gorge; it’s about a quarter mile away at a different altitude and on a different underlying rock formation.
But that is a ridiculous level of granularity. If I’m trying to build a showcase garden of Maryland native wildflowers, should I exclude these two species because the one is naturalized and the other grows only in very specific locations?
The answer to that question consider the maxim “first, do no harm.” More on that next time.
*1Natural Resources Conservation Service
*2Flora of the Southern and Mid-Atlantic States, page 465
maps from USDA, NRCS. 2018. The PLANTS Database (http://plants.usda.gov, 19 February 2018). National Plant Data Team, Greensboro, NC 27401-4901 USA.