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Marsh Marigold: A Native Plant for Wet Edges


Marsh Marigold: A Native Plant for Wet Edges

In summer our thoughts turn for refuge to cooling streams and pond edges, and to memories of a spring blaze of marsh marigold and moving water. Early to bloom, and in lush leaf through summer, marsh marigolds (Caltha palustris) are a cold-hardy and water-loving perennial. They are also a native alternative to their diminutive lookalike, the highly invasive lesser celandine (Ficaria verna). Differentiating between the two plants is helpful to curb the spread of one, and to encourage the cultivation of the other.

Photography by Marie Viljoen.

Above: Marsh marigolds have between 5 to 9 petal-like sepals, and have a mounding habit.
Above: Lesser celandine has 8 to 12 petals, and a carpeting habit.

Both marsh marigolds and lesser celandine have buttercup-perfect, iridescent yellow flowers that signal their kinship: they belong to the Ranunculus family. But in North America lesser celandine, a transplant from Europe (it is also occurs natively in North Africa and West Asia), has mastered the insidious creep, smothering regional swathes of riverside and forest floor, altering habitats as it spreads its low but impenetrable canopy. Lesser celandine’s invasive status is mostly associated with the Northeast, but it is moving into the Midwest and occurs in the Pacific Northwest, too. In places where it grows beside moving water, flooding carries parts of the plant downstream, where they take root.

Above: Marsh marigolds at the Brooklyn Botanic Garden.

Marsh marigold’s species name palustris means “of marshes.” Varieties of marsh marigold have an unusually wide native distribution, described as circumboreal: The plants occur across the northern part of the planet (boreal means north), in North America, Europe, and Asia. The plant’s flowers are larger and more showy than lesser celandine’s. In terms of function, marsh marigold can stabilize stream banks, forming mounded, clumping colonies over time. The flowers’ pollen and nectar are a rich food source for native pollinators, and small mammals and ducks eat the seeds.

Above: Lesser celandine is very difficult to remove where it is widespread.

Lesser celandine removal sidebar: The removal of lesser celandine is not easy. If you have a few clumps, remove them at once. By the time a carpet has formed, the task is daunting, and complicated. Methodical mechanical removal, by hand, is best (although difficult), and vigilance is essential. Personally, I cannot recommend glyphosate (usually sold as Roundup).

Why not use glyphosate? There is its implication in the evolution of so-called super-weeds, for one thing. And while the Environmental Protection Agency (EPA) considers glyphosate “not likely to be carcinogenic to humans,” the International Agency for Research on Cancer (IARC) does classify  glyphosate as “probably carcinogenic to humans.” Quite the contradiction.

For your own rabbit hole research consider that the studies that the IARC relied on seem more in keeping with real-world situations and exposure than those employed on by the EPA. Glyphosate has been banned by California, and in 2020. New York banned the use of glyphosate on state property. Its use is especially problematic near water, or when associated with water tables (everything lands up in the water table). Glyphosate has been showing up in stream and air samples since 2011, and its knock-on effects on life forms other than the target-plant (from soil microbes to aquatic invertebrates) are being studied.

Above: Marsh marigolds favor flowing or oxygenated water.

Marsh marigolds thrive in moist soils: Stream and pond edges, rain gardens, and low-lying, occasionally flooded pockets in woodlands gardens are all good choices. They can tolerate shallow submersion in water, and can be planted in pond baskets or mesh bags at pond edges if your pond is lined. Full sun will produce the most blooms, but in shade the plants will create an effective, leafy cover.  Marsh marigolds are extremely cold hardy, from USDA zones 1 – 8.

Above: Marsh marigolds at Ward Pound Ridge Reservation, in New York.

Benefits of Marsh Marigolds:

  • Highly ornamental spring.
  • Lush foliage.
  • Toxins in the mature leaves make them deer resistant.
  • They are a stream and riverbank stabilizer.
  • The flowers’ nectar and pollen are very attractive to pollinators.
  • They are an appropriate alternative to lesser celandine as well as to yellow flag (Iris pseudacorus)
Above: The lush leaves of marsh marigolds.

Cheat Sheet

  • Marsh marigolds thrive near running water, as well as in or near oxygen-rich water (think pond-side, or in a rain barrel garden).
  • In hot summers, in full sun, they are summer dormant.
  • In cooler regions or in woodland shade, they keep their leaves.
  • They are hardy from USDA zones 1 – 8.
  • Marsh marigolds have been studied in connection with global warming, and its effect on wetlands.
  • Unopened marsh marigold flower buds can be pickled, after boiling or fermenting (raw, any Ranunculus can be toxic). (Sturtevant, 1919. Republished 1972.)

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