Sunday, October 2, 2011

Go for Goldenrod!

This is a good time of year to appreciate the flowers of goldenrod.  Goldenrod is the common name for plants in the genus Solidago, a group of perennials that bloom in late summer or fall throughout Georgia. Most people only see them as flowers on the side of the road, but keen gardeners recognize them for their value in the fall garden.

If anyone is still under the impression that goldenrod causes allergies, let me assure you that is not true, and there is a perfectly good scientific reason why. With that misunderstanding out of the way, we can now enjoy this plant for its many good qualities.

Thirty five (35) species of Solidago are found throughout Georgia – from the Blue Ridge to the Piedmont, then south to the Coastal Plain and west to our borders with Florida and Alabama.  Some goldenrods have very specific habitats and their name reflects that: Seaside goldenrod (Solidago sempervirens), Pine barren goldenrod (Solidago fistulosa).  Our most recognizable one, thanks to its aggressive roadside nature, is simply known as “tall” goldenrod: Solidago altissima.

Solidago altissima

Not all goldenrods are aggressive – that is another myth to dispel.  Aggressive goldenrods have rhizomatous roots, and Solidago altissima is one such species.  Other goldenrods do not spread by roots and are considered “clump forming”.  As with any plant that you consider adopting, research carefully the growth characteristics of the species to determine if the plant is a good fit for your location.

A wand-shaped inflorescence
Recognizing or identifying the different species of goldenrod can be a challenge.  Using the shape of the inflorescence is one key identifier.  The shapes fall into the following rough groups: a plume-like arrangement (tall goldenrod has this), an elm-branched arrangement, a club- or wand-shaped arrangement, and a flat-topped arrangement.  If you are using Weakley’s Flora, be advised that he uses five keys to separate them and information about the leaves is needed to choose the right key (so be sure to make note of the leaf characteristics).  He also makes a distinction as to whether the inflorescence is secund or non-secund (and other keys do as well).  Secund is defined as “arranged on one side only”.  Solidago sphacelata is a good example of a secund arrangement (and I'm still trying to figure out that non-secund guy on the right!).

Secund
Non-secund

Identification of goldenrod in the wild, like many plants, is hampered by natural forces that cause plants and blooms to be shaped "imperfectly". I've got tall goldenrod (S. altissima)
Solidago nemoralis
that is less than 2 feet tall because the deer keep trimming it down.  That plant will be shorter than defined for that species and the blooms will likely be irregularly shaped.  On the other hand, I recently figured out that I have a species of shorter goldenrod - Solidago nemoralis.  That species will never be tall, it has basal leaves, secund blooms, and the leaves are quite differently shaped - all factors that would quickly distinguish it from tall goldenrod.

Yet until this year, I just assumed it was short occurrences of the other!  Sometimes you just don't see the differences until you are ready to look for them.


Goldenrod has been getting more attention lately for its benefits to wildlife. Anyone that has observed it for just a few minutes can see that pollinators flock to it.  Bees, wasps, beetles, flies and butterflies are attracted to the bright yellow blooms, a signal that pollen and nectar await them.  Butterflies also lay eggs on the leaves - it is host to over 120 different species of insects in this regard.  In the fall, puffy seed heads are relished by small birds like goldfinches that easily perch on the sturdy stems to eat them.

Early plant explorers sent seeds and roots of goldenrod from North America back to Europe for cultivation and European gardens have used these North American native perennials since then.  Goldenrod is also a popular flower in professional floral arrangements.  With proper selection and siting, it can be a bright addition in your garden as well.  Here are a few recommendations for goldenrod species and cultivars that are generally available at nurseries or native plant sales:

Part-shade species:

Blue-stem goldenrod, Solidago caesia (clump-forming)
Zig-zag goldenrod, Solidago flexicaulis (rhizomatous)
White goldenrod, Solidago bicolor (clump-forming)



Flowers in the leaf axils of Solidago caesia


Full-sun, clump-forming species:

Autumn goldenrod, Solidago sphacelata ('Golden Fleece' is almost a groundcover)
Showy goldenrod, Solidago speciosa
Wand goldenrod, Solidago stricta
Seaside goldenrod, Solidago sempervirens
Anise-scented goldenrod, Solidago odora
Gray goldenrod,  Solidago nemoralis


 Solidago sphacelata 'Golden Fleece'
Photo by L. Almand


Full-sun, rhizomatous (spreads by roots) species:

Rough-stem goldenrod, Solidago rugosa (the cultivar 'Fireworks' is very showy)
Tall goldenrod, Solidago altissima


 Solidago rugosa 'Fireworks' makes a spectacle of itself



I hope this has helped you see that goldenrod has much to offer.  Choosing to use it in your garden should be easy - just think of it's beauty, versatility, and value to wildlife.  So if you come upon one of these dependable perennials at a plant sale, be sure to "Go for the Goldenrod"!

7 comments:

  1. Hey L, thanks for the categories! That will make Goldenrod shopping much easier.I would ,however, suggest that you pull-out that black boxy thing on the heavy wooden stem in last photo. Very invasive! I have seen streets where they have popped-up in front of every house!!

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  2. I dearly LOVE Goldenrod, and so do the pollinators. With all the different kinds and their staggered bloom times, it seems like it's been blooming for months. It always makes me a little sad though when the Goldenrod starts blooming because it means summer is over.

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  3. Jeff, you crack me up! I'm glad you like the categories.

    Julie - so true about the end of summer!

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  4. Very serious about the categories! I appreciate that you have wrangled all the latin names, common names, root structures, and habitat preferences into a 3x5 card size reference!

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  5. Ellen,
    Great goldenrod post and kudos to you for keying out so many. I have only begun to ID the more stranger species here. I have the 'Fireworks' in my yard, it's just starting to flower.

    Heather

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  6. I have 3 others that I am keying out now - I think they might be S. erecta, S. puberula, and S. squarrosa ... but we shall see! And I just found a fourth, but it may be S. squarrosa also; too soon to tell. I have been enjoying the effort.

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  7. I just planted some goldenrod in my garden last year - a bonus from a Bluestone Perennial order. I almost didn't plant it because I see the invasive kind all over here. But I figured this one had to be different, and I'm glad I planted it - it's been a joy to me, my garden, and the bees!

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