Monday, November 21, 2011

The Complementary Colors of Fall (Part 2)

Solidago flexicaulis
Zig-zag Goldenrod
If I had to guess as to the most-unfairly-maligned native plant, I would certainly give some consideration to the Goldenrods.  These plants bloom just as we start feeling the first sniffles and sneezes of the Autumn hayfever season, flaunting their golden display right up until the first frost in many instances.  And, of course, we associate our grievous allergic condition to these highly visible and ornamental plants, not realizing they are not the culprits at all.

But it is not the showy Goldenrods (Solidago spp.) that are to blame; rather, another native plant, Ragweed (Ambrosia spp.) is at fault - a plant whose inconspicuous greenish flowers pale beyond insignificance when compared to the Goldenrods.  How do we know it's the Ragweed to blame?  Goldenrod pollen is so heavy, it just drops to the ground; in fact, you can often find the ground under a stand of Goldenrod carpeted with pollen.  Goldenrods, like other members of the Asteraceae, are pollinated by insects; by contrast, Ragweed is wind pollinated - its pollen has to be light enough to be carried off by the wind - right into our nasal passages and sinus cavities.

Solidago caesia
Bluestem Goldenrod
Goldenrod is one of Autumn's gems, along with our native Asters (which, as we now know, aren't really asters at all, although they are members of the Asteraceae.  So is Ragweed, by the way.)  I find it quite compelling that Mother Nature used plants featuring complementary colors - the purple tones of many of the asters and the yellows of the goldenrods - as the final movement in her yearly color symphony.  With only one exception (S. bicolor, which is native to Michigan and blooms silvery white), the flowers are yellow to gold in color.

Many of our native Goldenrods make admirable garden plants, aside from their beautiful color and bountiful nectar for late pollinating insects.  One of my favorites is S. flexicaulis.  Its common name, "Zig-zag Goldenrod", is derived from the fact that is stem subtly zigs and zags from one leaf node to the next, making it a great plant for children's gardens, for the behavior and resulting name.  It was when I saw the more sparsely flowered S. flexicaulis that I realized the Goldenrods are, indeed, members of the Asteraceae.  I had not realized that each "flower" indeed, like the largest Sunflower (Helianthus spp.) is composed of prominent, peripheral "ray flowers" (each of which exhibits one of the showy petals we associate with the family) as well as less-conspicuous, centrally-massed "disk flowers".  (I had the same "ah-ha" moment with Blazing Star, or Liatris, species.)  S. flexicaulis will spread, not with the wild abandon of S. canadense, but in a manner that can easily be controlled, and prefers woodland edges and dappled shade, contrary to common assumptions about Goldenrods as a whole.

Solidago rigida
Stiff Goldenrod
Another personal favorite is a plant I purchased from the Wild Ones tent at the Marshall Area Garden Tour back in 2010 (a great event if you can get there!)  S. caesia, or Bluestem Goldenrod, is similar to S. flexicaulis in that it is not as densely flowering as some species and also preferring woodland margins to wide open fields.  An elegant plant characterized by thin, lance-shaped leaves, the stems have a graceful arching habit similar to that of Solomon's Seal (Polygonatum biflorum).  The stems, true to the plant's common name, have a definite blue, or glaucus, cast, as well as a prunose bloom (think about how a plum's or grape's skin looks and you've got it).  S. caesia is a bit less aggressive than  S. flexicaulis, but either plant would light up the edges of a woodland flower garden at an otherwise rather lean time of year, especially planted near another woodland native, White Snake Root (Ageratina altissima).

Solidago rigida
Stiff Goldenrod
One of the things I find most fascinating about the Goldenrods is the variety of foliage - ranging from narrow, lance-shaped leaves, to coarse, paddle-like foliage, some smooth, others hairy or downy - making a collection of the plants visually interesting even when they aren't in bloom.  That is, in fact, how I've planted my Goldenrods, near one another so the variations in the foliage can be better appreciated; near my asters, so their brilliant yellows and golds are complemented by the Asters' cooler tones.

A more robust-looking plant, S. rigida, or "Stiff Goldenrod", is as desirable as a foliage plant as it is for its densely-packed flower heads.  Characterized by large, relatively coarse leaves covered in gray downy fuzz (much like Helianthus mollis, or "Downy Sunflower"), which gives them a silvery cast.  The foliage of the basal rosette is very "Aster-like", but the flowers are Goldenrod all the way, densely held in a flattened, more ball-shaped panicle; get up close, and you can really see the flowers' typical "aster" form.  This can be a big plant - two to five feet, make it a great companion for your untrammeled New England Asters (Symphyotrichum novae-angliae).

Solidago canadense
Canadian Goldenrod
Goldenrods can spread by seed but they also increase by means of spreading rhizomes, generating leafy rosettes that produce tall, leafy stems topped by panicles, cymes or spikes composed of tiny little daisy-like flowers.  This habit is exemplified by S. canadense, the plant we usually see as we're cruising Michigan's autumnal highways.  I have "had" this plant in my garden, not by intention; it came in with some topsoil, probably in seed.  (The seeds, like those of many of our native "asters", are fluffy and disperse with the wind.)  Although the flower heads are quite lively with loosely arching stems packed with yellow blooms, the plant itself is quite aggressive and probably not workable for the typical gardener, spreading quickly through most soil types.  So, you might want to give a pass to S. canadense but do check out the other numerous garden-worthy native Goldenrods; no Autumn garden is complete without at least a few of them!
All photos Don Schulte copyright.

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