Tom's Blog

Saturday, September 15, 2012

Showy goldenrod as a savanna species

Showy goldenrod patch in an open area of a bur oak savanna (Unit 11A)
Showy goldenrod (Solidago speciosa) is in glorious color right now, and can be found in most of our planted prairies. It is also noteworthy because it is an attractive feature of the more open areas in our oak savannas, as the above photo shows. Like some of the other goldenrods, it grows in patches but it is not rhizomatous like Canada goldenrod and hence is "well behaved" in prairies and savannas.

What is attractive about showy goldenrod is that its flower heads can be up to a foot long and are arranged in colorful panicles. The flower stalks don't curve downward like most other goldenrods, but stand straight up. This arrangement, together with the dense cluster of stems, is responsible for the attractive color.

This species is native to Pleasant Valley Conservancy, and all of the seed for our plantings is local. When we started seed collecting work in 1997 there was one site, called "Toby's Annex", where this species was present. The seed collected there was planted nearby in Toby's Prairie, where it flourished, and provided seed for other plantings.

The Curtis data (computerized by Umbanhowar and collated by Henderson) showed that this was a mesic prairie species, and since our oak savannas have extensive mesic areas, we used it in the seed mixes for all of the understory plantings. Over the years it has sorted itself out, and now we find it doing very well in the open savanna areas although not in the closed savannas. My rough estimate is that it prefers sites with a canopy cover of 30% or less.

According to the botanical literature, this species is not very aggressive and hence should not get out of hand. Our experience at Pleasant Valley agrees with this idea. In fact, the original stand of showy goldenrod at Toby's Annex has almost disappeared over the past dozen years, although a few small patches still remain.


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