Restoring Black Cohosh

A five-foot tall, decades-old perennial wild plant like black cohosh doesn't just "appear" out of the ground in the spring. It punches out, purple and unfurling, both graceful and primeval. From atop its thick, dark stem, three separate appendages unfurl into horizontal plateaus of compound foliage, each deeply incised leaflet spreading out until the leaves collectively occupy several square feet.

If the plant is to flower that year, a stem later shoots up over the primary foliage. The flowering stem briefly holds a miniature cluster of flower buds, like baby corn, above reduced lateral leaves. In midsummer, the flowers open, small whitish starbursts of stamens on an upright stemmed stalk called a raceme. Blooms open sequentially from the bottom of the raceme to the top, an upwards-moving column of white taking several weeks to reach from the bottom of the raceme to the narrowed tip. 

There the flowers stand, chest-high or taller above the ground, catching the afternoon sun as it slants below the canopy. A typical colony of hundreds or even thousands of black cohosh plants illuminates the understory, a legion of tall white flowering wands glowing against the dark trunks and long shadows of the forest.

The flowers have a deeply musky odor, a stale smell that enters the nostrils and sits in the back of the nose, like old popcorn smell in a movie theater. Attracting bumblebees, honey bees, and flesh flies, the flowers are pollinated and each fertilized embryo forms a crescent-shaped seed. The seeds nestle in two-lipped capsules, attached by short stems onto the central stalk of the raceme just as the flowers were. As the seeds mature, the entire seedhead turns a deep black and awaits dispersal.

There is a large colony of black cohosh on a flat ridgetop near where I used to live in central New Jersey. Walk there in the late fall, and the dried leaf litter of black oaks crunches beneath your feet, and the thin rattle of black cohosh seeds sound almost subaudibly as you brush past decumbent stems bringing seedpods nearer the earth. 

I once walked a circle around the colony there and found it covered over 4 acres. The colony on this oaky ridgetop numbers in the thousands of stems, many of which are evenly spaced, though the colony meanders, grows ragged, misses spots, and thrives densely in others.

Once I was explaining to my wife Rachel something I had read - that black cohosh seeds had no documented dispersal methods other than falling to the ground and hoping for the best. This, in contrast to the many species that are specially adapted for dispersal by wind, birds, adhesion to fur, ants, and so on. By all accounts its dispersal distance is limited to the immediate surroundings of the parent plant except in exceptional circumstances. One scientific account I read described its effective dispersal distance as "0 meters" per year.

When I told this last figure to Rachel she disagreed. Rachel pointed to the dried, bleached flower stems left over from this year's cohosh bloom. They no longer stood shoulder height to us, but were tipped over and hovering practically horizontal to the ground -- scattering the seeds still held in their rattlepod heads at a fairly regular distance of three to four feet from the parent plant.

Regardless, cohosh is not a fast colonizer by seed. Black cohosh is dispersed neither by bird, mammal, reptile, nor wind, except in rare and accidental circumstances.

Perhaps it is this highly regularized dispersal mechanism - measured faithfully every year in cohosh stems, like some archaic measurement unit of rods or fathoms - that is to account for the regular, and highly colonial distribution of individuals within black cohosh populations.

So how long does it take for a four-acre grove of cohosh to arise, presuming a single parent, spreading largely by seed, one to two meters every year or two, tacking in some extra time for these long-lived and large-rooted forest herbs to reach sexual maturity? The math is beyond me, but it takes long enough, I'd presume, to qualify the plants as ancient. Even if the trees aren't "old growth", the black cohosh may be.

Black cohosh must migrate long distances on occasion. The patch on the oaky ridgetop got there somehow. Some seed-laden mud on the hoof of a deer? A hurricane? Regardless, cohosh doesn't easily cross highways, golf courses, or suburban developments. Though we have a higher percentage of forest in the Northeast now than for most of the last two centuries, the majority are young woods, gone feral from abandoned agriculture. Some are suitable habitat for cohosh, but it may be centuries before these post-agricultural woods are actually reached by the small, black, half-moon shaped seeds falling from their chest-high perch.

Black cohosh has proved a tremendous herbal ally for people. It is one of the best-selling medicinal herbs on the global market, used to balance hormones during menopause, and for musculoskeletal support. In 2014, $42.5 million dollars worth of black cohosh was sold just in mainstream outlets in the United States. It is in danger of overharvest in the Appalachian forests it calls home. But the problem can lead us to the solution, and towards being better stewards of the species.

Black cohosh has helped us, and we can return the favor by bringing cohosh, plant by plant, seed by seed, to the young hillsides and rocky slopes where it once bloomed and can do so again.

There's a special relationship that we humans have to plants. We can promulgate plants. We can reproduce plants. Other animal species disperse seeds, for sure, but we humans can bring plants to new places in very deliberate ways. With plants, we can take the foundational building blocks of ecosystems, (pro)create them, and make more of them.

Right now, we have many degraded human landscapes that detract from the function of the living Earth. But if our human landscapes are rich and abundant with plant life, then our terrain is functional. Because plants are the basic building blocks for addressing our environmental concerns. Sequestering all of that carbon and maintaining atmospheric gasses in livable proportions. Building living soils. Plants link the world of soil and stone to the world of sun and sky. We need plants because they mediate all of the foundational processes of the current epoch of life.

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From a forthcoming book on restoring native edible and medicinal plant species.  Stay tuned and thanks for reading!