Chiwaukee Prairie Preservation Fund, Inc.

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Invasive Plants

Garlic Mustard (Alliaria petiolata)
When: Mid April – early June

Garlic Mustard (Alliaria petiolata)

Dame’s Rocket (Hesperis matronalis)
When: Mid April – early June

Dame’s rocket (Hesperis matronalis)

Yellow Rocket (Barbarea vulgaris)
When: Late April – June

Yellow Rocket (Barbarea vulgaris)
Photo by Eric Howe

Meadow Hawkweed (Hieracium caespitosum)
When: Late May – early June

Meadow Hawkweed (Hieracium caespitosum)
Photo by Eric Howe

Curly Dock (Rumex crispus)
When: June – August

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Deptford Pink (Dianthus armeria)
When: June-July

Deptford Pink (Dianthus armeria)
Photo by Eric Howe
Shallow rooted and easy to pull/bag. Annual removal for the past four years at known locations have sharply reduced populations.

Yellow Sweet Clover (Melilotus officinalis)
When: June-July

Yellow Sweet Clover (Melilotus officinalis)
Photo by Eric Howe

White Sweetclover (Melilotus albus)
When: July-August

White Sweet Clover (Melilotus albus)
Photo by Eric Howe

Queen Anne’s Lace (Daucus carota)
When: July – September

Queen Anne’s Lace (Daucus carota)
Photo by Eric Howe
Queen Anne’s Lace (Daucus carota)
Photo by Eric Howe
Queen Anne’s Lace (Daucus carota) shown above forming seeds. At this “basketing” stage, we remove/bag the seed heads and pull/drop the remainder of the plant.
Photo by Eric Howe

Comparison of Queen Anne’s Lace with the native Cowbane

The NATIVE Cowbane (Oxypolis rigidior) shown above superficially resembles Queen Anne’s Lace. Note that there are less umbelets that make up the entire umbel.
Photo by Eric Howe

Common Mullein (Verbascum thapsus)
When: Late May – August

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Common Mullein (Verbascum thapsus) Photo by Eric Howe

Common St. John’s-Wort (Hypericum perforatum)

Common St. John’s-Wort (Hypericum perforatum)
Photo by Pam Holy

Common St. John’s Wort has translucent ‘dots’ on the leaves when held up to the light (left image above) as well as black dots along the margins of the petals (right image above and below).
Photo by Eric Howe

Common St. John’s-Wort (Hypericum perforatum) Photo by Eric Howe

Comparisons of Common St. John’s-Wort with other the native species

LEFT: The NON-native Common St. John’s Wort (Hypericum perforatum)
RIGHT: The NATIVE Shrubby St. John’s Wort (Hypericum prolificum). The native lacks the two features noted above and has a profusion of yellow stamens.
Click the above image for greater detail.
Photo by Eric Howe
LEFT: The NON-native Common St. John’s Wort (Hypericum perforatum)
RIGHT: The False Toadflax (Comandra umbellata) for comparison. This native, which may no longer be in bloom when St. John’s Wort blooms, has alternate leaves versus the opposite leaves of Common St. John’s Wort.
Photo by Eric Howe

Grasp the base of the Common St. John’s Wort stems as low as you can get (where it transitions to the root crown at soil level) and pull slowly as to allow one to get as much of the roots as possible. If one pulls too fast, or if only one of the stems of a multi-stem plant is pulled, the stem(s) is more likely to break off from the root.