Sweetfern is a deciduous shrub growing to 2-3 feet in height and indefinite dimensions in width do to heavy suckering. Branches, generally borne upright, range from pale yellow brown to a deep red brown, and tend to be hairy. Leaves are long and linear, up to 5 inches, with deeply cut dentations reminiscent of fern fronds. New leaves develop light green and darken with age. This contrast can be quite ornamental on the plants. Separate male and female flowers are borne in catkins or dense, cylindrical clusters that develop in April and May. Male catkins are elongated, female shortened ovals. Olive brown, burr like fruits develop from pollinated female catkins by early summer. Sweetfern seems to prefer dry, sandy, acid soils and is often found in disturbed areas such as roadsides.
The name Sweetfern is derived from the soap like aroma of the crushed leaves as well as the graceful, dissected appearance of the foliage. Sweetfern is a nitrogen fixing plant, capable of removing nitrogen gas from the atmosphere to use for growth. Sweetfern accomplishes this feat by partnering with a soil borne Actinomycete fungus. The fungus grows amidst Sweetfern roots developing nitrogen-collecting structures called nodules. Sweetfern benefits from the fixed nitrogen while the fungus benefits from the nutrients and water collected by the plant’s roots. This ability to fix nitrogen allows Sweetfern to grow in dry infertile soils and develop lush green foliage where other plants decline.
Sweetfern is considered best used in naturalistic plantings due to its suckering nature. However, it has been used quite successfully in a mixed border or as an informal hedge lining paths. Gardeners will need to occasionally cut or dig out suckers to maintain a controlled shrub. Root cuttings derived from trimmed suckers can be used to propagate new plants. Consider Sweetfern for planting along driveways or as erosion control along dry slopes.
Sweetfern is native to the northeastern United States and southeastern Canada.
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