Pond Project: Water-willow

After several years hiatus, I am again growing native wildflowers for restoration projects.

Pond this winter.
Pond this winter.

This year I have a farm pond restoration project. A pond that was dug about thirty-five years ago has become obscured by staghorn sumac to the point where it can no longer be seen, or even visited without a machete. Nothing much else native has come in to colonize it. The idea is to remove the sumac along most of the shore and replace it with diverse native vegetation.

Of course, the scope of the project grew during the winter, after seed collecting season had finished, so the species I am growing for this year are limited to those I happened to have plus a few I needed to buy, minus those that are too fussy to germinate. Once again my refrigerator is home to plastic baggies filled with damp paper towels, wherein seeds that require cold stratification are getting a cool, moist approximation to winter.

A species I have never grown before, Decodon verticillatus, seed purchased from Gardens North, is tiny, requires light to germinate, and needs three months cold stratification – according to the package, which in this case I will trust. Kristl Walek, the owner of Gardens North, is practical and experienced, and I have been able to find almost no other information on growing D. verticillatus. Thus, the seed had to be sown on top of a flat of damp potting soil, bagged up to keep it moist, and put in a refrigerator. I persuaded the client to put it in his refrigerator, so it is not taking up space in mine. (Note to self: do this more often.) Because I didn’t put in my Gardens North order until late February, the flat won’t come out into the warmth and light until June 1st. That’s fine. There is little point trying to push the growing season with natives, especially ones you don’t know well. Chances are seeds in the wild would not begin to germinate until the ground around them warmed thoroughly, perhaps in late May.

I am trying to think of the common name for Decodon verticillatus and the only name I can come up with is water-willow.

Seriously? Water-willow? The plant likes moist soil, has pretty purple-pink flowers all along its herbaceous stems, which arch and trail gracefully, making it perfect for planting at the edge of a pond. It is not at all related to the woody willow family of shrubs and trees. Perhaps it is the misleading common name which has prevented this plant from becoming popular. (Or perhaps it is just another example of the way North American horticulturists ignore North American plants.) I own a lot of books about gardening with native plants and I just got a whole bunch more books about ponds from the library, and none of them even mentions D. verticillatus.

Decodon verticillatus: Pelee Marsh
Decodon verticillatus: Pelee Marsh

I first saw this pretty plant years ago in Pelee Marsh, and because I had seen it in the deep South and not elsewhere, I  just assumed it was a Carolinian species. Then I saw it again, a lot of it, on a Field Botanists of Ontario trip to a wetland  well north of Kingston, on the Frontenac axis. Range maps put water-willow growing well up into southern Quebec, so it is suited to my Zone 4b project. I don’t know why it is not seen more places. Perhaps it is one of those plants whose distribution is just mysteriously spotty and sporadic. Or perhaps the practice of managing water-levels in cottage country for boaters rather than the native inhabitants has eradicated water-willow from places it once grew. I am sure it is doing fine, deep into swamps and marshes, but it would be nice to see it from time to time from a canoe on a day paddle.

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Trish Murphy

Artist: botanical, still life, and natural history illustration. Garden designer: native plants and naturalistic gardens