The end of summer is tinged with melancholy, with the last days of vacation and the return to school. I imagine that plants, had they emotions, would feel that same twinge of sadness. Early fall is a glorious time of year botanically speaking, but nipping at its heels is dormancy and the stillness of winter. So the vegetative message may be, "Live in the moment."
Goldenrods are excellent examples of this philosophy. This time of year, you're bound to see their infectiously cheerful golden hue just about everywhere. Since most of us don't go out into nature as often as we'd like, our interactions with wild plants may be limited to the blur of vegetated roadsides from a car window. This works in their favor, as goldenrods often dominate these kinds of marginal habitats.
There are about 100 species of goldenrods, nearly all native to North America. In New York State alone, there are close to 30. Now in various genera (Euthamia, Oligoneuron, et al.), we'll take a tour of the largest genus, Solidago with nearly 70 species.
Although Solidago comprises many species with different physical characteristics, goldenrods do have a "look." Typically they have broadly linear leaves with small teeth around the edges (margins). These leaves are arranged in an alternate fashion along upright stems that are between two to five feet tall.
As this is yet another member of the large Composite family (Asteraceae) (what can I say, I'm partial to them) there is an inflorescence within an inflorescence. Peer closely into the spray of floristic sunshine -- what looks like individual flowers are in fact clusters of even smaller disk and ray flowers (florets). Nestled in the center are "perfect" disk flowers, meaning they have both reproductive parts, male (stamens to produce pollen) and female (pistils to produce ovules). Whorled around them are ray florets, all of which are female. Goldenrod blossoms burst on the scene in late summer and last through fall, with individual plants in bloom for three weeks.
Despite the presence of both pollen and ovules in the same flower, goldenrods are self-incompatible, meaning they cannot produce viable seed. This makes having same species neighbors with different genotypes important, especially since goldenrods often reproduce vegetatively, forming large, dense colonies of clones. If successfully pollinated (more on the process later), the flowers will bear fruits called "achenes." These are small, dry and seedlike and resemble caraway seeds. Atop each achene is a troll doll-like tuft of white hair called a "pappus," which facilitates being carried aloft by the wind in search of new habitat.
The species you've surely encountered most often is Canada goldenrod (S. Canadensis). This plant likes to be near people -- edges of agricultural fields, vacant lots, roadsides and railroads. It's known for its ability to stand up to invasive bullies like mugwort. But its aggressive tendencies here translate into being an invasive bully itself in parts of Europe. Back in the U.S., its neighbors and kin along dry roadsides and meadows are early (Solidago juncea), gray (S. nemoralis) and rough goldenrods (S. rugosa).
A late summer stroll on the beach will yield seaside goldenrod (S. sempervirens). This evergreen plant of coastal plains sometimes also occurs where road salts are used. As most of New York City's perimeter has been developed, I like to think of its curbside persistence as a reminder of the coastal community that once was there.
Most people are surprised to learn that there are shade tolerant goldenrods hiding on the forest floor. Instead of standing upright, blue-stemmed goldenrod (S. caesia) arches out as if straining for more sunshine. Its flowers are axillary (along the stem at the leaves) instead of clustered at the top. Zig-zag (S. flexicaulis) and elm-leaved (S. ulmifolia) goldenrods are cohorts in its woodland retreat.
There are even Solidago that like to keep their feet wet, like bog (S. uliginosa) and rough-leaved (S. patula) goldenrods.
This proliferation of goldenrods in the landscape may have worked against them. They bloom right when hay fever sufferers like me start to rub their itchy eyes. Runny-nosed and miserable, people look for answers and the ubiquitous yellow flowers fit the bill. Alas, it's a case of "wrong place at the wrong time" -- goldenrods are the whipping boy for ragweeds.
Fall allergens are primarily produced by ragweed (Ambrosia spp.). Ragweed produces an abundance of lightweight pollen that is carried on the wind. These tiny specks travel far and are easily inhaled. Goldenrod, on the other hand, produces entomophilous pollen that is relatively heavy and sticky. It is rich in protein as an enticement to the insect visitors that will do the work of pollination.
Goldenrods and ragweeds tend to hang out in the same places, hence the false accusations. People usually don't recognize the wind pollinated flowers as flowers because they tend to be inconspicuous, green-ish and small. Why would a plant spend energy calling attention to flowers it doesn't need pollinators to visit? Better to make many miniscule flowers, let the wind carry the pollen away and hope that some sticks on another tiny flower of the same species. Check it out for yourself -- these ragweed flowers are not going to win any horticultural awards.
Speaking of insect visitors, goldenrods have a long list that would make any Manhattan nightclub owner jealous. They are a varied bunch, especially the pollinators: long-tongued bees, short-tongued bees, wasps, flies, beetles and a few butterflies and moths. Feeding on goldenrod's foliage is another popular attraction. Most moths visit the plants as caterpillars to munch on the leaves. Fellow eaters include various lace bugs, leafhoppers and leaf beetles.
There are thriving, teeming worlds within a single goldenrod stem, far more than can be recounted here. This makes them fascinating to examine up close. The next time you are out for a walk or a drive, don't be so quick to pass them by.
Second photo caption: Field of seaside goldenrod (Solidago sempervirens) in Conference House Park, south shore of Staten Island, NY.
Also check out this exclusive TDG video of Marielle Anzelone talking about Wildflower Week and the importance of protecting, and exploring, urban nature:
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