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tall purple seed head weed

A cool season perennial wheatgrass that speads extensively by long white rhizomes (underground stems.) Leafblades are twice the width of bluegrass and tend to be rough in texture. A claw-like protrusion of the leaf called an auricle clasps the stem. One of the most distinguishing characteristrics is a ring of root hairs every 3/4 to 1 inch along the rhizomes. The lower leaf sheath of the stem is hairy.

Cool season perennials that form rosettes with prominently veined leaves. The leaves of blackseed are oval shaped and 2 to 3 inches across with purplish stalks; broadleaf plantain has smaller leaves without purplish coloration. Both species have rat-tail like seed heads that are several inches long.

Cool season perenials that are among the first plants to bloom in the spring. Prefer at least partial shade. Flower color varies from very light blue to deep purple. Occasionally become troublesom in lawns.

*Illustrations and descriptions provided by Lawn Weeds and Their Control, North Central Regional, Extension Publication No. 26, 1992.

For more information on phragmites identification and control, visit this page:

Bull thistle (Cirsium vulgare) is a widespread biennial that reproduces by seed. Even though it looks nastier than Canada thistle, it’s actually an easier weed to handle. Here’s how to identify bull thistle:

For more information on Brazilian elodea identification and control, visit this page:

Parrotfeather (Myriophyllum aquaticum), a species of milfoil that’s another Class B noxious weed, also reproduces vegetatively in North America. You can identify parrotfeather by:

Phragmites (Phragmites australis). Photo courtesy of Washington State Noxious Weed Control Board.

Next, spotted knapweed (Centaurea stoebe). This Class B noxious weed will also be blooming and starting to seed this month. A lover of well-drained soils in full sun, the short-lived perennial thrives in dry, disturbed sites throughout King County.

You can identify spotted knapweed by: