Issue 13, August 25, 2014

Lesser Known "Weeds" -- Fireweed

Erechtites hieracifolia (L.) Raf. ex DC. is commonly known as fireweed, pilewort, American burnweed, or simply Erechtites.  Although it has been found in most Illinois counties, it's not a very common plant to most and because it's not easily recognized by many, it is often referred to as being a mystery weed.  In fact, this "weed" is not included in most of the weed identification reference books I own.  Still, I get asked about it yearly.

The one book I found this plant featured in is, "Wild Urban Plants of the Northeast:  a field guide."  The one and only time I saw this plant growing was near Lincoln Park Zoo in Chicago which is fitting perhaps.  It prefers full sun, moist soils, and disturbed sites and is commonly found growing in sidewalk cracks, along fences, and in minimally maintained landscapes.  This plant is well known for its ability to germinate on land that has recently burned, hence the name fireweed.  Also known as pileweed, this plant was used by native Americans and early European settlers to treat hemorrhoids (piles).

Fireweed, an aster, grows rather tall and unbranched, reaching 6 to 8 ft.  The leaves and stems are bright green and smooth.  The leaves can grow up to 6 to 8 inches long by 2 to 3 inches wide.  They are alternate, oblong and pinnately lobed with irregular teeth along the margins.  The roots are shallow and fibrous. 

Leaves are smooth with toothed margins. Photo by Richard Hentschel.

The flower heads are somewhat unique in that they are tight and tubular-shaped, enclosed by smooth, green bracts.  Panicles of these are found in the upper stems.   The corollas (individual disk florets) stick out just barely above the bracts.  The flower heads develop into white puffballs.  The seeds are then carried by the wind with the aid of the soft, white hairs.  The flowers appear in late summer or early fall and aid greatly in identification of this plant. 

Flowers are uniquely shaped.

For more information and pictures of this plant, please see: (Michelle Wiesbrook)

Michelle Wiesbrook

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