I was first introduced to lowland loosestrife on a 2022 South Carolina botanizing trip with Zac Hill and Patrick McMillan. I was shocked that I’d never heard of Steironema hybridum before, despite it being a widespread US native from Canada south to Florida. How is it possible that this late season-blooming perennial wildflower is completely unknown by gardeners. The first problem is the name. It was originally named in 1803, and since then, it’s been tossed around between the genus Lysimachia and Steironema, until 2018 DNA test showed it to be correctly assigned to Steironema. The second part of the name that keeps many folks from growing it is the specific epithet “hybridum”. Sadly, there’s a large contingent of native plant fundamentalists, convinced that hybrids are the devils work, despite they are so unreflective to realize that they are each hybrids. We have truly failed in our attempts at such basic education. In this case, the plant is actually not a hybrid, but simply suffers from such a name. Sadly, it will be omitted from gardens simply because people would be riduculed to have a plant named “hybridum” in their gardens.
In the wild, lowland loosestrife is found in wetlands, although we have found it to perform extraordinarly well in typical garden soils, when grown in full sun. For us, it forms a 2′ tall x 3′ wide, non-running patch, that bursts into flower for us in late August. We have plans to propagate this to share sometime next year. Let’s hope there are more than a couple of folks who like it as much as we do.
If it’s adaptable to 10a, I’m in!
This would be an interesting addition to a low lying or wet area in any garden. It is certainly a plant that I would like to add to my garden. I look forward to seeing it as a Plants Delight offering next year.
I’ll buy it.