There is a toxin here. The air or soil is harbouring a pollutant and the only indication is a cluster of flowers on the edge of an abandoned field. The flower is Tradescantia, normally they are purple, but these are streaked white and pink. The plant responds to genotoxins, toxins that damage genes, by altering its pigment. This trait has put it to use by researchers across the world as an inexpensive and reliable bioindicator. Species from the Tradescantia family have tracked heavy metals in German mines, air quality in Brazil and nuclear radiation in Japan. The plant is less expensive than any device and often just as accurate. Now these trustworthy harbingers are across the street from my house and responding to something otherwise unseen.
A plant speaks with its body: a wilting leaf, the rich green of vigorous growth, a closed blossom tracking the sun. A human can only discern what these cues mean through direct experience. These exchanges are the universal language between our two living kingdoms, plant and animal. When Tradescantia petals respond to pollution they otherwise appear healthy; the stem remains turgid and the leaves are still vibrant. It is a tough and beautiful plant, thriving on roadsides and cultivated in gardens.
The species nearest my home is Tradescantia virginiana. A native to the Americas, remaining despite centuries of the destructive alteration of the continent’s ecosystem. The genus has numerous variations, with many species rapidly mutating in the presence of genotoxins. The deliberate cultivation of Tradescantia as a bioindicator reflects a relatively new relationship between plants and humans. The use of a plant specifically for its ability to detect potentially lethal chemicals, rather than as a source of sustenance or beauty, is itself indicative of the complexity of the ecological continuum. Here, in Southern Georgia, Tradescantia is a weed, offering portents to any keen eye.
In the quirky yet stern 1950’s booklet ‘Weeds and What They Tell’, Ehrenfried Pfeiffer attempts to give a brief summary of what common weeds indicate about soil conditions. His observations are helpful for any gardener without access to soil testing. Dominate plants can indicate soil pH; for example, wood sorrel prefers acid soils, and sage brush thrives in alkaline. With this knowledge, a gardener can add amendments or grow plants preferring those conditions. Pfeiffer distinguishes between, weeds (lowercase) and WEEDS. He writes, ‘Wherever weeds grow, they will tell something, and wherever WEEDS grow, they indicate a failure of man.’
A field full of resilient weeds can be a source of hope. I often look upon untended land and think, life finds a way; wishing in the expanse that a home is being made for other, more fragile beings. Yet year after year, the same plants expand their territory, almost mimicking human monocultures. Here in the deep south, late winter is awash with the warm golden red of sour dock singly occupying the fallow cotton fields. The famed, now almost beloved kudzu, is still found in vast stretches along roadsides, creating sculptural representations of the trees they have swallowed. In the shallow swamps, whorled tangles of invasive hydrilla dominate the homes of the native American water lily. Today, Pfeiffer’s warning to listen to weeds is even more stark as hydrilla is now proving to be a vector for a never-before-seen bacteria dubbed ‘the eagle killer’. In the endless heat of the American South, these plants are adapting rapidly with uncanny intelligence. What are they trying to tell us?
Humans tend to believe nature sends us messages. I, too, search for secrets in rustling breezes or thoughtfulness in the bowing head of a mockingbird. Yet, I feel more grounded when I decide there are no hidden messages intended for me; to instead experience a communion, a call away from the self, and into the living community. In order to stop echoing my own anthropocentrism, I must resist the idea that nature is there to tell me anything.
These resilient plants are responding to something, and often what can be discerned is quite obvious: climate, pollution, habitat destruction. Becoming aware of what the plant tells us awakens our own deadened senses. Whether we notice a thriving mass of an invasive species, or the colour of newly formed petals on an indigenous plant, our observations can subtly reveal what we have shuttered ourselves away from.
When weeds flourish in disturbed habitats they are efficiently responding to an altered centre of balance. The emergence of an invasive is not separate from a system. An illuminating cycle of human destruction and ecological response can be found in the water hyacinth. This aquatic plant often invades wetlands containing elevated levels of arsenic and is now being investigated as a potential bioremediation agent. Water hyacinth not only does well in these polluted lakes and streams, it also absorbs arsenic from the water. Despite this knowledge, the typical response to an infestation is to smother the plant with herbicides rather than address habitat loss or pollution. Our pursuit of invasives is attempting to make it right, yet the weeds continue in our failure, no matter how many we pull or poison.
I go to the field in the morning to observe the Tradescantia petals fading to pink. Their pigment is undoubtedly different from the others in my garden. I’ll never know what it is responding to, but I accept the pollutant could also be somewhere inside me. Our bodies are not passively accepting toxins. We are engaging in a dark dance — the flower blinks in new shades, my cells slightly alter their form. The trace particles become part of us, and we change together. None is isolated from the other.
The pale Tradescantia will be mown soon, the flowers cut back to the ground until they emerge again. The roots will feed in the soil, the leaves will drink in the sun, and it will blossom anew. It has learned to thrive by transforming — by refusing to be destroyed by change. Whether or not we choose to pay attention to the lesson is entirely up to us.
Image painted in response to this essay by Hannah Helton hannahhelton.com
