Field Thistle Cirsium discolor (Muhlenberg) Sprengel    Synonyms: Carduus discolor.
Kingdom Plantae   >   Division Tracheophyta   >   Class Magnoliopsida   >   Order Asterales   >   Family Asteraceae   >   Genus Cirsium   

Status:

Frequent throughout Maryland in fields and along stream banks and roadsides (J. Hill/MNPS).

Description:

One of only two Maryland thistle species with the underside of the stem leaves white; the other being Tall Thistle. The two species can be differentiated by looking at the leaves. The leaves of Field Thistle are deeply pinnatifid, compared to the shallowly lobed leaves of Tall Thistle.

Relationships:

Pollinated by bees and butterflies. Caterpillars of Painted Lady butterflies feed on the foliage. American Goldfinches eat the seeds and line their nests with the tufts of hair that develop on the achenes (fruits). Ruby-Throated Hummingbirds visit the flowers for nectar. (J. Hill/MNPS)

There are 170 records in the project database.

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Field Thistle in Caroline Co., Maryland (8/28/2016). Photo by Wayne Longbottom. (MBP list)

Field Thistle, with visiting male Zabulon Skipper, in Montgomery Co., Maryland (8/31/2013). Photo by Jane Hill. (MBP list)

Field Thistle blooming in Allegany Co., Maryland (8/22/2018). Photo by Mark Eanes. (MBP list)

Field Thistle in Anne Arundel Co., Maryland (8/9/2011). Photo by Bill Harms. (MBP list)

Field Thistle in Prince George's Co., Maryland (8/30/2017). Photo by Bill Harms. (MBP list)

Field Thistle blooming in Howard Co., Maryland (8/30/2013). Photo by Joanne Solem. (MBP list)

Field Thistle in Dorchester Co., Maryland (9/4/2016). Photo by Jim Brighton. (MBP list)

Field Thistle in St. Mary's Co., Maryland (9/12/2014). Photo by Jim Stasz. (MBP list)

Field Thistle blooming in Anne Arundel Co., Maryland (9/13/2010). Photo by Bill Harms. (MBP list)

Field Thistle, with silky fruits being released, in Montgomery Co., Maryland (11/9/2014). Photo by Jane Hill. (MBP list)

Field Thistle (unopened flower) in Howard Co., Maryland (8/30/2013). Photo by Joanne Solem. (MBP list)

Field Thistle (dark upper side of leaf) in Anne Arundel Co., Maryland (9/13/2010). Photo by Bill Harms. (MBP list)

Field Thistle (light underside of leaf) in Anne Arundel Co., Maryland (9/13/2010). Photo by Bill Harms. (MBP list)

Field Thistle in Caroline Co., Maryland (9/3/2021). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

Field Thistle in Kent Co., Maryland (10/4/2015). Note the whitish undersides of leaves. Photo by Bill Hubick. (MBP list)

Field Thistle in Anne Arundel Co., Maryland (9/13/2010). Note that flower head shows white-striped bracts with short needle-like spine. Photo by Bill Harms. (MBP list)

Field Thistle in Harford Co., Maryland (9/10/1983). Photo by Jim Stasz. (MBP list)

Field Thistle in Howard Co., Maryland (9/25/2018). Photo by USGS PWRC. (MBP list)

Field Thistle (winter aspect) in Calvert Co., Maryland (3/17/2018). Photo by Bill Hubick. (MBP list)

Field Thistle in Caroline Co., Maryland (10/31/2020). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

Field Thistle in Caroline Co., Maryland (10/1/2020). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

Field Thistle in Caroline Co., Maryland (10/1/2020). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

Field Thistle in Montgomery Co., Maryland (9/4/2019). (c) Jennifer Wright, some rights reserved (CC BY-NC). Photo by Jennifer Wright via iNaturalist. (MBP list)


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