Hypericum kalmianum L. - Kalm's St. John's Wort


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Hypericum kalmianum - (image 1 of 5)



Family: Hypericaceae


Moist, calcareous sand, sandy bogs, calcareous swale borders.




Limited to the Great Lakes.


Woody shrub to 3' high. Leaves opposite, simple, linear-oblong to oblanceolate, to 2" long, usually under 8mm wide, blue-green above and glaucous beneath. Stems brown, 4-angled. Flowers yellow; petals 5, glandless; stamens more than 20; styles 5; born in 3-flowered cymes. Fruit a 5-celled capsule.


Flowers mid June to early October

Wetland indicator: Facultative wetland-

This shrub is quite a sight in full bloom with the blue waters of Lake Michigan behind it. It is apparently cultivated, although not as well-known as other St. John's Worts. Dirr mentions a cultivar called 'Ames' that was selected for it's rounded shape. It is hardy to zone 4.


Dirr, Michael A. 1998. Manual of Woody Landscape Plants:
Their Identification, Ornamental Characteristics, Culture, Propagation and Uses.
5th ed. Champaign, Illinois: Stipes Publishing L.L.C.


Peterson, R. T. and M. McKenney. 1996. A Field Guide to Wildflowers:
Northeastern and North-Central North America.
Houghton Mifflin Company. Boston, MA


Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region.
Indiana Academy of Science. The Morton Arboretum. Lisle, Illinois.




 Michael Hough 2005