Any discussion of native plants, whether for your garden, a restoration project, or simple curiosity about the flora on your back forty, has to eventually arrive at the question, “is this plant native or introduced?” You’d think it would be an easy question but it turns out to be more complex than you might imagine.
I’m on the state board of the Washington Native Plant Society. We take the concept of “native plant” pretty seriously and have had long discussions to nail down a definition. Here’s what we came up with, published on the What is a Native Plant? WNPS web page:
“Washington native plants are those species that occur or historically occurred within the state boundaries before European contact based upon the best available scientific and historical documentation.”
That seems straightforward enough. If it was growing in Washington before Europeans arrived it’s native. But what about the influence of native peoples on plants? There is growing evidence that they manipulated the landscape to garden the forests and meadows for optimal food production. Through trade, did they also import California or Oregon plants to Washington? It’s difficult to know for sure, but we can expect DNA testing in the coming years to attempt to answer the question.
The discussion about native provenence is occurring currently on the members-only e-mail list for the Native Plant Society of Oregon. It’s not a new discussion, as we were reminded of an article in the very first issue of Kalmiopsis, the NPSO journal. The issue is online. Scroll through the PDF to page 13.
It’s fairly obvious when traveling across most western states that regional habitats and environments support different plant communities. So a plant native to western Washington counties may not be native east of the mountains. Even with a single county you can find diverse habitats. I live in Whatcom County, Washington. It’s nestled against the Canadian border, has a saltwater shore, and rises to a 10,778’ snow-capped volcanic summit. With few exceptions, what grows at sea level won’t also be found on an alpine ridge. You can also notice differences between the east and west sides of a hill, or between a north and a south slope.
In regions that were settled and farmed by Europeans over 300 years ago much of the landscape has been radically altered and there may not be good records of what was growing here before the first ships arrived. Even in more recently settled farm country, such as Oregon’s Willamette Valley, there may be little of the original vegetation remaining in what was once native prairie.
So where does this leave us, we who care about planting natives in our gardens and landscapes? Where do we go to find out what is native and what has been introduced?
Fortunately, there are now numerous online resources that summarize scientific research. Most of the data ultimately comes from on-the-ground research and is documented in herbarium records. I’ll share the primary tools I used when researching Wildflowers of the Pacific Northwest and that I’m using currently as I work on Trees and Shrubs of the Pacific Northwest (due out in 2014).
For the big picture, I go to the USDA Plants database. I usually have a target species in mind and type the scientific name in the search box. Let’s use coltsfoot, Tussilago farfara, as our first example.
This was one of the first plants to bloom on rocky hillsides near my home in central West Virginia. I grew up thinking it was native. However, in the course of conversation with another east-coaster last weekend I looked it up on PLANTS and discovered that Tussilaga farfara had been introduced. I remember it looking like a native, growing in the wild, with modest populations in specific places and never getting invasive.
The distribution map on PLANTS shows Tussilago farfarain Washington state, but I’ve never seen it out here.
The PLANTS database will also let you search for everything that grows in your state and generate a checklist or do an advanced search. If you haven’t played with the PLANTS database, go exploring some rainy day.
Now let’s consider another coltsfoot, Petasites frigidus.
This is another early-blooming plant, one that’s familiar in the northwest. Is it native? PLANTS says, “yes,” it’s native throughout its range in North America.
You’ll note that the PLANTS database maps show distribution by state. You can click the states and get county-level distributions. I prefer, however, to go to regional or state resources for my localized information because more detail is available.
Working my way south, I can check the status in British Columbia using e-Flora BC, the electronic atlas of the plants of British Columbia. Entering Petasites frigidus in the search box I learn there are four varieties of the species in BC. When I click on the first entry I get a lot of information about this plant, including a point distribution map.
For Washington, I use the Washington Flora Checklist. Both native and non-native taxa are included, differentiated by type face.
Perhaps a bit more user-friendly is the University of Washington Herbarium Image Collection. I usually click on Name Search and then enter the species I’m looking up. Here I can get county-level distribution maps that I can click and see the underlying herbarium records from the same database as the Checklist.
The Washington Native Plant Society website includes plant lists for the entire state and for each county. They’re compiled from field trip reports and make no effort to be comprehensive. They’re a great resource when heading out on a hike to see what others found on the same trail previously. I haven’t found anything similar for other states but that doesn’t mean they don’t exist.
Another portal is the Consortium of Pacific Northwest Herbaria website. There are many ways to refine a search here, which spans the records of 13 individual herbaria.
For Oregon, the go-to reference is the Oregon Flora Project checklist and accompanying plant atlas. The checklist links to PDFs by family, so to find our Petasites I browse the genera beginning with “P,” click Asteraceae, and then use the search function within Adobe Reader to get to the relevant page where I find that P. frigidus is considered native in Oregon.
The Oregon atlas works faster if you browse by name (which opens lists to choose from) rather than typing a name in the search box. The resulting maps are customizable to an extent and are clickable to reveal the source records.
For California I go to CalFlora, usually starting with the search page. Using our Petasites again, I get a page showing there is only one variety in the state. Clicking on the species link yields a page with a clickable distribution map, a couple of photos, and links to further information.
All of the websites cited so far are relatively friendly for ordinary plant lovers. The true plant geek will also want to visit the online Flora of North America. It’s still a work in progress, as is the publication of printed volumes. That means you won’t always find a species you want to learn about, but if it’s been published then FNA is generally the current authoritative source. See the record for Petasites frigidus and prepare to open your botanical dictionary.
The state of the art in online plant databases is constantly evolving. There’s much more information available today than in 2003 when I was working on my wildflowers book.
For other states you’ll have to do a little sleuthing, and not all states have gotten their herbarium records online yet. I searched for “herbarium records West Virginia” and discovered that only some of their records have been databased, viewable on the Flora of the Southeast portal. A similar search for Michigan turned up the Herbarium of the University of Michigan website.
See what you come up with for your state and share the results in the comments.
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