Anemone quinquefolia L.
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| Wood anemone flowering in mid-May 2018. |
Wood anemone is a low-growing spring ephemeral also called nightcaps, a name desdribing its nodding, cap-like flowers at night. Its slender stems usually bear three green or purple-green whorled leaves, each leaf typically divided into three parts. The lateral leaflets are often deeply lobed, so it appears that a single leaf is divided into five parts. The species name quinquefolia means "five-parted."
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| Left: A stem of wood anemone showing a whorl of three divided leaves. Right: A single leaf showing three divisions, or leaflets. The lateral leaflets are deeply lobed, giving the appearance of five leaflets. |
Starting in late April or early May, the plants produce white or pink-tinged flowers with five sepals but no petals. In the center of each flower are numerous stamens with white anthers, all surrounding a cluster of simple, separate pistils. These flower characteristics are typical of plants in the buttercup family, Ranunculaceae (ra-NUN-cue-LAY-cee-ee), to which this plant belongs.
Wood anemone is pollinated by insects that are active during the day -- mainly small bees and flies, according to the USDA Forest Service. As mentioned earlier, its flowers close at night and also on cloudy days, a habit thought to preserve and protect their reproductive parts when pollinators are less active.
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| Left to right: Wood anemone plants flowering in May; closeup of a single flower showing five white sepals, numerous stamens with white anthers, and a central cluster of pistils; a dissected flower showing the position of sepals, stamens, and pistils. |
By late spring, wood anemone forms fruits called achenes (ah-KEENs). These dry, indehiscent (non-splitting) fruits each hold one seed. Each achene develops from a single pistil, and because the flowers bear many pistils, they also bear many achenes. At maturity, each achene is just a few millimeters long and about half as wide. Achenes and their seeds are disseminated by ants.
Wood anemone reproduces not only by seed but also by rhizomes, underground stems that grow more or less horizontally and give rise to more above-ground plants. It's common to find wood anemone growing in dense patches as a result.
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| Wood anemone spreads in part by the growth of rhizomes, slender underground stems that produce above-ground plants. Rhizomes also bear roots to absorb water and nutrients. |
In late spring or early summer, wood anemone begins to die back, as true ephemerals do. The leaves fade and the patches thin, leaving only seeds and rhizomes to produce next year's growth. The genus Anemone means "windflower" or "daughter of the wind" for the fleeting appearance of many its species each spring.
As is clear from its common name, wood anemone thrives in the part shade of wooded habitats. It's commonly found on forest floors and edges but sometimes also in full sun. The species has an extensive range generally covering eastern North America. In Minnesota, wood anemone is found in all but the southwest counties of the state.
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