Rosin Weeds are not weeds at all. They are really fine ornamental herbs that provide for substantial wildlife activity and add lots of pizzaz to a garden. Silphiums are some of the more shining, luminous jewels you can incorporated into your prairie-meadow if you’ve got one. Several Silphium species are native to our region and all are easily grown, adaptable, dependable, and extremely persistent garden plants. That is, if you can find them in the nursery trade available for purchase or …if can get some seed. Most all of mine were originally grown from seed.
Silphiums are no minor player when it comes to garden boldness. My friend Gail calls them “tall boys”, and puts them in the same category as Joe Pye Weed, Iron Weed and Big Bluestem. All are adaptable, long to establish but long-lived, and permanent plants that almost never need care.
They’re exquisitely beautiful organisms. Excellent garden plants, no doubt. They have a huge capacity in the landscape for specialized ecological function. They feed good-weird bugs and stuff (they’re highly attractive to butterflies and other very specialized pollinators, y’all).
I’ve heard some of my northern gardener-friends say that they are weedy, but I have not had that kind of luck yet. In the fifteen years or more I’ve grown Silphiums, I have never had enough show up via re-seeding and they have rarely become prolific in a planting, only somewhat, maybe. But they seem to be more than prolific above the Mason-Dixon line. Dumb luck, I guess.
Rosinweeds are for royalty. They are for refined gardens and wildscapes, too! They are horticultural clout. Vertical botanical bling! Some of Europe’s most visited gardens have American Silphiums in them. The Brits Dunnett and Hitchmough use them in their famous wildflower work. And where we live they are tame, yet seductive.
Most Silphiums grow as large-leaved herbaceous plants, big leafy rosettes with tall terminal stalks laden up-top with big butter-yellow ‘ray and disk’ flowers. In the best conditions, during the best year for rain, the tallest ones, the Compass Plant and Prairie Dock, both can grow flower stalks to eight or ten feet tall.
Who wants an eight foot tall herb in their garden? Me, that’s who!!!!
above: a single flower of Will Fleming’s awesome “curly leafed” Rosin Weed, almost five inches across. not too shabby.
Actually, Rosinweeds are just foliage clumps in the landscape for months in the spring and early summer until the plant prepares to bloom, sending stalks skyward. The photo above,(click it to enlarge it) taken by Jovonn Hill, of the Pulliam prairie landscape in Chickasaw County, Mississippi, with Prairie Dock, Silphium terebinthinaceum, just emerging in April, after a controlled burn. Cool thing is you can see right through the stalks of Silphiums when they bloom, like, the stalks almost become invisible.
Here are the Silphiums I have grown for some years now, in my gardens.
above: Silphium laciniata, the Compass Plant, emerging after burn in spring in the Covington garden. 🙂
Compass Plant in flower and fruit, Eunice, Louisiana
Gail and UWA student Colton stand amongst hundreds of ancient Compass Plants at the oh-so-amazing Epes, Alabama chalk glade.
above: seedling of Compass Plant from hand-harvest seed from Epes, growing at the Black Belt Prairie Garden, University of Western Alabama, Livingston, Alabama, May, 2014.
link to cool photos of Compass plant
S. gracile or Slender Rosin Weed’s distribution range, above, a plant found both in Pine forests and Prairies in Louisiana. Lush rosettes, entire leaves, high-oil seed makes for an excellent wildlife plant. Gracile is a real southerner with a red-neck attitude, often kind of slouchy and grinning. No, really, its a very plant with a good attitude. Niche Gardens, a specialty native plant nursery in Chapel Hill, N.C offers this species for sale.
S. simpsonii, Simpson’s or Tall Rosin Weed is a non-Louisiana Native given to me by Texan nurseryman Peter Loos in the mid 1990’s. Good-naturalizing, adaptable, seed excellent for wildlife. Looks very similar to gracile.
early growth of Silphium simpsoni, above
S. integrifolium, Prairie Rosin Weed, is found associated with inland prairies of Louisiana and the Jackson Belt prairies of Mississippi. Its a Rosin Weed with conspicuous leaf arrangement. A vertically attractive course-textured plant.
above: the burly-tough rigid stem and leaves of Silphium integrifolium
above, Silphium integrifolia in full-glory, Harrell Prairie Botanical Area, Bienville National Forest, Scott County, Mississippi
S. terebinthinaceum, Prairie Rosin Weed (above), is not found naturally occurring in Louisiana and is only found in one county in Mississippi and one in Alabama. Its at the southern end of its range here in the GS. The largest leafed Silphium, by far. Awesome. Tony Avant of Plant Delights nursery in Chapel Hill grows and offers it for sale. Mine hasn’t bloomed yet and it is at least five years old but the leaves are very large and showy without flowers. It may have a lot to do with the seed coming from clay-specific soils to acid soils here in Covington, duh.
above: S. perfoliatum, The Cup Plant, is an uncommon plant in Louisiana, with records in only one Parish. More commonly found in much of the eastern U.S (minus Texas), this guy has the distinction of forming “cups”, where water collects where the ‘perforated’ leaves join the stem. Bold and strongly structural architecture.
S. asteriscus, Starry Rosin Weed, is one I have only grown for four or five years now. It seems to be very floriferous and a bit shorter than most other species.
Silphium (origin, Will Fleming) is a curly margined form of a yet-unidentified (um, I forget) species with a distinctive leaf form. I’ve grown this plant for five or so years. A worthy ornamental.
Propagation of these species is fairly easy if you have some good, viable seed. Just sow the seed in a good soil mix and barely cover the seed, enough to keep it moist. Germination will come pretty quickly unless its the dead of winter. Field grown Silphium seed is a horse of a different color. Seed I sowed of laciniata, in 1998 and 99 didn’t show up for several years, being out-competed and beat-up by unwanted competition. So eliminate competition in the field before sowing and maybe save yourself some years of waiting and wondering.
actual flowers of Silphium
after flowering, seed setting
The oily seed of Silphium is covered by a wafer-like coating
Get down, get tall, get Silphium, and get with it, folks!!!!
the link below is the short version of the Flora of Pulliam Prairie paper.