Common Name of Species: Swamp
Entry Author: C. Friedl,
Key Characteristics: Swamp thistle can be identified by its hollow stems and its bracts which are sticky and cobwebby.
Leaves: Leaves are divided, with very deep lobes and sharp prickles. Can be as long as 10 inches, and as wide as 4 inches. Leaf width gets smaller towards the stem of the leaf. Essentially lanceolate in in shape.
Flowers: Flower bracts are prominent and sticky like cobwebs. The bracts are not sharp or spiny like the bracts of other thistles. The flower head are approximately 1.5-2 inches wide, and are deep purple or lavender in color. Petals are tubular, small and erect, creating a bell shape. Flower can grow in small clusters or alone.
Stem: Stems are hollow, ribbed and smooth, with possible branching towards the very top.
Height: Can grow to be 3-6 feet in height.
Branching Pattern of Leaves: Leaves grow alternate to one another.
Conditions/Habitat: Tends to grow in wet, swampy places, including low meadows and wet thickets.
Range: Swamp thistle is distributed across North America.
Newcomb, Lawrence (1977). Newcomb’s Wildflower Guide. New York: Little, Brown.
McKenny, M. & Peterson R.T. (1996). Peterson Field Guides: Wildflowers Northeastern/ North-central North America. New York: Houghton Mifflin.
NRCS (2004). Plants Database, Version 3.05 (http://plants.usda.gov).
National Plant Data Center,
Baton Rouge, LA 70874 USA.
This page was created by: C. Friedl,
Last updated 12/16/05