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St. John's-Wort (Hypericum)

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Home « Michigan « Montmorency « Hypericum

St. John's-Wort Genus Details

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St. John's wort is native to S.E. Europe and Asia. It is generally used as a ground cover and it is drought tolerant. Bright yellow flowers appear in late July and are 3" in diameter. In autumn, the flowers turn purple. St. John's Wort is used in herbal medicine as a mood enhancer.
Common St. John's-Wort (Hypericum perforatum).
Common St. John's-Wort (Hypericum perforatum).
Common St. John's-Wort (Hypericum perforatum).
Common St. John's-Wort (Hypericum perforatum).

St. John's-Wort Allergy Info

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Generally low to moderate allergic reactions have been noted with this genus.

St. John's-Wort Pollen Description

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Grains are subprolate; the amb triangular and 3-colporate. The colpi are long and narrow and slightly constricted equatorially. The ora is lalongate and the opercula granular. The sexine is reticulate and the lumina small and polygonal. The intine is thin and thickened below the apertures.
Grains are 21-24 x 18-19 micrometers.

Species in This Genus

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Allergenicity Legend:
Mild Allergen Mild Allergen  |  Moderate Allergen Moderate Allergen  |  Severe Allergen Severe Allergen  |  Allergy Test Allergy Test Available
St. John's-Wort (Hypericum) is a genus of the CLUSIACEAE family.
This genus includes the following allergenic species:

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St. John's-Wort Genus Location

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The shaded areas on the map indicates where the genus has been observed in the United States. Click the map to see a full scale version of these allergy areas.
  - Native, observed in a county
  - Introduced, observed in a county
  - Rarely observed

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