An area cleared for restoration gives one group of plants just the opening they need.
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| Once bare soil, this area is now full of pioneers, plants adapted to disturbance. The tall plant in the center is American burnweed, Erechtites hieraciifolia. |
Some plants thrive on disturbance. They're made to capitalize on bare soil, direct sunlight, and little competition from other plants for water and nutrients. In ecological terms, they're pioneers, plants that are the first to occupy a bare or disturbed area, quickly grow, flower and set abundant seeds and die soon after, leaving conditions that better support the plants that follow them.
This process of replacement is called succession, and in this case it began in a small area that had been overtaken by buckthorn and other undesirable plants. The area was cleared to the ground, dug and tilled to remove small stumps and fragments that could resprout.
The resulting bare soil became something like a canvas, ready for planting with woodland species. Clumps of wild geranium (Geranium maculatum), wild ginger (Asarum canadense), wood phlox (Phlox divaricata) and other shade-tolerant perennials were transplanted into the space with hopes they will fill the understory with a native woodland community.
That will take some time. For now, pioneers have found a home at this site. Many of them seemed to come out of nowhere: They weren't there -- or weren't noticed -- before the area was cleared, but they're here now in a thriving assortment. American burnweed (Erechtites hieraciifolius) rocketed up, annual fleabane (Erigeron annuus) began covering the ground with its basal leaves, and black nightshade (Solanum nigrum) grew into bushy piles. In all, about 20 species of pioneers appeared in the first months of the restoration.
Some probably grew from seeds that had been in the soil for years, forming a seed bank. Seeds of both annual fleabane and black nightshade, for example, remain viable in the soil for more than 5 years, and nightshade perhaps as long as 39 years (1). Seeds of witchgrass (Panicum capillare) can survive in the soil for decades (2), and seeds of common mullein (Verbascum thapsus) can remain viable for an astonishing 100+ years (3), waiting for disturbance to germinate.
Most pioneers are annuals or biennials, plants that complete their life cycles in one or two years, respectively. At this site, some of the pioneers are native and some are introduced from Europe or Asia. Most are considered "weeds," but seen through an ecological lens, they have an important role to play. Native pioneers, especially, create the conditions that better support the plants that follow them. They do this by adding organic matter to the soil, preventing soil erosion, increasing the water-holding capacity of the soil, and providing shade for plants that don't tolerate full sun.
A few of the many pioneer species at this site are featured below, along with links to more information. The images are not to scale.
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| American burnweed, Erechtites hieraciifolia |
American burnweed, aka pilewort or fireweed, is a native annual in the aster family. Its buff-colored flowers appear to never open, but instead emerge just slightly from the top of a tube-shaped receptacle about 1/2 to 1 inch long. After pollination, the flowers produce tufted seeds spread by wind. American burnweed grows to 10 feet tall. In Minnesota, it's found mostly in the forested eastern half of the state.
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| Flower-of-an-hour, Hibiscus trionum |
Flower-of-an-hour, aka Venice mallow, is named for the brief time its flowers open. This annual from Eurasia was probably brought to North America as an ornamental, but it has since spread beyond garden borders to become a problem plant in some locations. A member of the mallow family, flower-of-an-hour is related to garden Hibiscus, hollyhocks, basswood trees, and even cacao. It flowers from July into September.
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| Black nightshade, Solanum ptycanthum |
Black nightshade, another native annual, is related to tomatoes and peppers. It gets its name from its dark purple, almost black fruits when they are mature. It is a branched and somewhat bushy plant that grows 2 to 3 feet tall. The leaves, stems and immature green fruits are especially high in solanine, a chemical that can be toxic to people and other animals.
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| Bittersweet nightshade, Solanum dulcamara |
Bittersweet nightshade is also present and newly abundant in this recently-cleared area. Unlike black nightshade, bittersweet nightshade is an introduced perennial that is more vine-like than bushy. Its
flowers are the same shape as black nightshade but are purple. Mature fruits are bright red. Like black nightshade, leaves, stems and unripe fruits are toxic. Bittersweet nightshade isn't a pioneer, but favors open or partly shady and often wet habitats.
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| White campion, Silene latifolia |
White campion is an annual or short-lived perennial originally from Europe. Like other pioneers, it thrives in disturbed locations but it can tolerate some shade. Male (pollen-producing) and female (seed-producing) flowers are on separate plants. To use the botanical term, this species is dioecious (dy-EE-shus), literally meaning "two houses." After pollination, female plants form brown, urn-shaped capsules containing hundreds of seeds each. This one held an estimated 400-500 seeds, and it was only one of a dozen or so on the plant.
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| Witchgrass, Panicum capillare |
When the inflorescence (flower cluster) of witchgrass first emerges, it looks like its name: a witch's broom. Eventually the inflorescence expands into a branched, open, airy panicle that at maturity becomes a tumblegrass: it breaks off from the plant and blows around. Witchgrass is a native annual. Like many pioneers, witchgrass seeds need light to germinate. Tilling the soil, as was done here, likely brought long-dormant seeds up to the surface, where they were exposed to sunlight.
Cited References
1. Nightshades. Cornell CALS. Website accessed Sept. 6, 2026.
2. Witchgrass. Cornell CALS. Website accessed Sept. 6, 2026.
3. Common mullein, Verbascum thapsus. Susan Mahr, University of Wisconsin-Madison. June 9, 2025.
