Signs of Fall 6: Some Fall Plants

(Some of the “science” parts of this blog were also used in a post published in September 2015)

Photo by D. Sillman

Photo by D. Sillman

On my drive to work I go past many “abandoned” fields. This time of year, though, these fields are stunningly beautiful in their array of autumnal colors and textures. Golden rod is the dominant plant (or dominant group of plants!) in most of these old fields, but it is well framed by clouds of the flowers of white snake root, and the orange and yellow flowers of jewelweed. Most fields also have the tall, deep purple flowered stalks of Joe Pye weed and iron weed punctuating all of the greens and golds. Finally, to finish off the very “Impressionistic” canvas of these old fields, there are also the scattered pink flowers of Pennsylvania smart weed usually visible on the edges of mass of plants. If you have the time to stop and take a closer look at the vegetation, you see dozens and dozens more species filling in all of available spaces! The closer you look, the more you see!

The fields look soft and inviting with all of these wonderful “weeds!” Often on the road-side or drainage ditch-side of the fields stands of Japanese knotweed (Fallopia japonica) grow in dense, monocultural, palisades that literally shade and choke out all of the other plant species under and around them. Knotweed is an exotic invasive that has taken over many thousands of acres of formerly diverse native vegetation.

All of these flowers, though, both native and invasive, are covered with pollinators (especially honey bees!). The fall honey that they will make will be dark and full of flavor and, speaking for myself anyway, is just the thing to help us survive the coming long, cold winter!

Photo by D. Sillman

Photo by D. Sillman

Golden rod is called “summer’s end” in England. Its appearance announces the fading summer and starts the ecological countdown to frost and, eventually, winter. There are twenty native species of goldenrod (genus Solidago) in Pennsylvania and another hundred plus species around the world. Solidago species have an amazing ability to crossbreed with each other and, so, close examination of any goldenrod patch is sure to reveal a wide range of types of individuals.

Goldenrod’s coincident flowering with the onset of the “hay fever” season has led some to assume that its pollen causes this late summer malady. Goldenrod pollen grains, though, are very large and sticky and are dispersed not in the wind but, rather, on the bodies of pollinating insects like bumble bees, honey bees and soldier beetles. The absence of wind dispersal makes this pollen a very unlikely contributor to “hay fever” allergies. “Hay fever” is mostly an allergic reaction to ragweed (Ambrosia spp.) and its great, airborne clouds of allergenic pollen. Scattered among the goldenrod are numerous, very unassumingly flowering, ragweed plants.

Photo by D. Sillman

Photo by D. Sillman

There are two recognizable species of jewelweed in our area fields. Both have the same small, very distinctive, trumpet-shaped flower, but one species grows quite tall and has yellow flowers (probably Impatiens pallida or the “pale jewelweed”) while the other species is shorter and has orange flowers  (probably Impatiens capensis or the “spotted jewelweed”). Dense mixed stands of both species border the open fields and often extend back into the shady areas of surrounding woods.

Jewelweed is widely thought to be a natural remedy and preventative agent against the delayed hypersensitivity reaction triggered by skin contact with the oils of the poison ivy plant (there is a lot of poison ivy, too, mixed in with the golden rod of the field and the jewelweed of the field edges!). There have been a number of controlled studies looking into the influences of the leaves and fluids of jewelweed on skin rashes, but none of them have clearly demonstrated any effective anti-inflammatory or even any anti-pruritic (anti-itch) impacts. There is some suggestion, though, that chemicals in the jewelweed fluids may very subtly alter the chemical structure of the poison ivy oils and, possibly, make them slightly less effective as a trigger for their delayed hypersensitivity reaction.

Photo by D. Sillman

Photo by D. Sillman

White snake root (Ageratina altissma) is a member of the traditional Eupatorium botanical group (as is Joe Pye weed (Eutrochium spp.)). This has been an incredible year for white snake root! I have never seen it growing so thickly along all of the sunny edges of my field at home and around the fields I pass on my way to work.  These plants with their clusters of bright white flower heads seem to shimmer and glow even in pale, morning or evening sunshine!  White snake root, though, like all of the Eupatoria, is very poisonous to animals. Its poisons can be transferred to the milk of a cow (or any other lactating mammal that might ingest the plant) and can cause “milk sickness” syndrome. Milk sickness is a very serious and potentially fatal condition. Extirpation of this plant from areas inhabited by grazing animals is extremely important. Animals are especially likely to consume white snake root during drought years as failing pastures force them to forage on less and less palatable plants. A historical note:  Abraham Lincoln’s mother, Nancy Hanks, died of milk sickness when Lincoln was nine years old.

Photo by J. Grandmont, Wikimedia Commons

Photo by J. Grandmont, Wikimedia Commons

Witch hazel (Hamamelis virginiana) is another notable plant of autumn, although we have to walk out into the woods in order to see it. Witch hazel is a large shrub (or small tree … the debate about this classification rages on!) found extensively throughout Western Pennsylvania. A witch hazel shrub (I fall into the “shrub” side of botanical argument!) has numerous basal branches that are six to eight inches in diameter that spread out laterally into an arching,

Witch hazel flowers Photo by D. Sillman

Witch hazel flowers Photo by D. Sillman

dome-like shape. It can grow twenty to thirty feet tall (OK, a thirty foot tall, woody plant sure sounds like a “tree” to me!). Witch hazel shrub/trees flower in the autumn, long after the flowering season has passed for most trees (or shrubs). Its flowers are bright yellow and complete and, so, are potentially self-pollinating. Pollination is usually accomplished, however, by a wide variety of insects. Although pollination occurs in the autumn, fertilization of the ova does not occur until the next May. The developing fruit, then, coincides with the timing of fruit formation seen in most of the other fruit producing plants of the ecosystem. Humans in many cultures utilize witch hazel for a variety of medicinal purposes. The bark and leaves are used to make topical medications for the treatment of cuts, abrasions, hemorrhoids, eczema and other skin conditions. Native Americans also brewed a medicinal tea with its leaves.

Witch hazel has been described as a “docile” plant within its natural communities (sort of the opposite of the invasive knotweed!). Its slow rate of growth and spread make it an unlikely ecosystem invader and often restricts it to stable, long-undisturbed forest sites. Out on the Penn State New Kensington Nature Trail, we have a beautiful witch hazel thicket on the far side of the stream that has not appeared to change over the thirty years I have been monitoring it! Slow growth, slow reproduction and its steady equilibrium within its habitats are the hallmarks of this interesting shrub/tree! It is worth the long walk down the Nature Trail to the ravine and the stream to see its yellow, fall flowers.

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