PROTECTING WISCONSIN'S BIODIVERSITY

 
 
   
 
Scientific Name Common Name Global Rank State Rank Federal Status WI Status

Slender St John's-wort (Hypericum mutilum)

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Photo by Merel R. Black

 

Counties with Mapped NHI Occurrences

Slender St John's-wort (Hypericum mutilum), a Wisconsin Special Concern plant, is found in mesic meadows, marshes, and along streams. Blooming occurs from mid-July through mid-October, fruiting September through October. The optimal identification period for this species is mid-July through October.

 
 
 

Slender St John's-wort is an herb or shrub, 1-8dm tall, with 5-parted yellow flowers in a branched cluster, with very reduced bracts up to 0.2mm wide. Individual flowers are 3-4mm wide. Its fruits are dark purple, ellipsoid capsules 2.5-4mm long. Leaves are stalkless, oval to elliptical and rounded on both ends, 1-4cm long.

Of other similar Hypericums, H boreale has wider bracts of 0.5-2mm wide, H majus has 5-nerved lanceolate leaves, and H canadense has linear-oblanceolate to lanceolate leaves with 1-3 nerves.

Can be propagated via sprigs. Blooming occurs from mid-July through mid-October, fruiting September through October.

Annual or perennial. The optimal identification period for this species is mid-July through October.

Slender St John's-wort prefers acidic, rocky or sandy soils and is found in mesic meadows, marshes, and along streams.

Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.

Avoid broadcast spraying of herbicides and use care with spot spraying.

Species of Greatest Conservation Need (SGCN) are associated with habitats (or natural communities) and places on the landscape. Understanding relationships among SGCN, natural communities and ecological landscapes help us make decisions about issues affecting SGCN and their habitat and how to respond. Download the Wildlife Action Plan association score spreadsheet to explore rare species, natural communities and ecological landscape associations

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the Wisconsin Wildlife Action Plan because lack of information can threaten our ability to successfully preserve and care for natural resources.