Scientific name: Caltha palustris
Family: Ranunculaceae
By Robert Spencer, Over the Dam
A week after daffodils show their whites and yellows the colorful show in my Pondside Garden begins, especially along the damp banking. Buds pop up from the broad green leaves of the eight Marsh Marigolds. The day that our Siberian Pear (Pyrus ussuriensis) reaches full bloom with its white and pink flowers, those bright yellow flowers burst at the water’s edge. Other perennials and shrubs are beginning to show their vitality, but the burst of bright and sparkling yellow contrasted with the broadening radiant green leaves leads the way into spring.
Caltha is often confused with Buttercups, being in the same botanical family. It is much closer to that yellow wildflower than it is to common annual marigolds. However, it’s 2-1/2” to 4” flowers and 2-7” dark green leaves make it easy to identify. Although native to our climate zone, it is now rare to find volunteer masses in the wild. For those gardeners who have a stable shoreline, the species can grow to a height of 2’. In my own garden whose water level is determined by the flow through Keoka dam, the eight-plant cluster thrives in the spring freshet before the dam is set to reduced summer flow.
Marsh Marigold is not fussy about soil but does needs six or more hours of full sunlight to be happy. Excess summer sun exposure may lead to dormancy. I have planted a screen of Flag Irises (Iris versicolor) in deeper water to protect the caltha with tall flat leaves, which reach a height of 2-1/2’ tall in June. If yourCalthas are planted in an area where roots can stay damp, no fertilization should be needed because nutrition is taken from silt and nutrients contained in the water and decomposition of dead foliage in the moist soil. Once your colony is established, rhizomes may be taken through division in the Fall to expand massing along the waterline.
The marigolds are deer resistant. They provide a good source of nectar and pollen for insects. Leaves and flowers are mildly poisonous, so no part of the plant should be eaten, even though foliage and rhizomeswere used by Native Americans to treat colds and sores, to induce vomiting, and to aid in difficult childbirths.
Caltha palustris plants grown in Maine are available in many local garden centers. Make sure that you are purchasing “palustris.” There are several other Buttercup species available which are not specified for use in wet soil.
In the next issue you will meet Bee Balm (Monarda didyma).It is anxiously pushing its leaves above a drier space slightly higher than the Marigolds.
Sources:
Magee, Dennis W., Freshwater Wetlands
Nearing, William, National Audubon Society Nature Guide: Wetlands
Melchert, David B. “How to Create a Streamside Garden,” The Environmental Gardener, Brooklyn Botanic Garden Record
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