Cirsium pitcheri

Sand Dune Thistle

FWS Focus

Overview

Characteristics
Overview

The Pitcher’s thistle (Cirsium pitcheri) is one of many rare or declining species inhabiting dunes of the Great Lakes region. This distinctive dune plant, often referred to as the dune thistle, was first noted by Dr. Zina Pitcher about 1827 at the Grand Sable Dunes of the Upper Peninsula of Michigan. Pitcher’s thistle is a monocarpic (flowers and sets seed only once), perennial, herbaceous plant, generally flowering after a 5-8 year juvenile stage. The stems and leaves of juveniles and adults are woolly-white, and the leaves are deeply pinnatifid with the lobes less than 1 centimeter(cm) wide and up to 4 cm long.

Scientific Name

Cirsium pitcheri
Common Name
sand dune thistle
Pitcher's thistle
FWS Category
Flowering Plants
Kingdom

Location in Taxonomic Tree

Genus

Identification Numbers

TSN:

Characteristics

Characteristic category

Life Cycle

Characteristics
Life Span

Pitcher’s thistle appears to have a small between-year seedbank, with seeds remaining viable for about three years. This suggests a buried seedbank may not strongly buffer population stability when plants are destroyed. Seed dispersal to nearby suitable habitats may be more important for population stability than the seedbank.

This monocarpic (once-flowering) plant produces a vigorous rosette that may mature for ca. 5-8 years or more before it flowers.

Life Cycle

Pitcher’s thistle appears to have a small between-year seedbank, with seeds remaining viable for about three years. This suggests a buried seedbank may not strongly buffer population stability when plants are destroyed. Seed dispersal to nearby suitable habitats may be more important for population stability than the seedbank.

This monocarpic (once-flowering) plant produces a vigorous rosette that may mature for ca. 5-8 years or more before it flowers.

Characteristic category

Physical Characteristics

Characteristics
Size & Shape

The stout, prickly, dune species, Pitcher’s thistle, grows for five to eight years before it flowers. Its non-flowering form is a rosette or cluster of silvery leaves and its flowering form typically has one stem with many branches. The entire flowering plant may grow 3 feet tall, but can also be as little as 6 inches and flower. Cream or pink flowers grow at the end of branches and from the leaf axils. Leaves are finely and deeply lobed and may be one foot long.

Color & Pattern

The leaves and entire plant are blue-green in color and densely covered with white-woolly hairs. The mature leaves are deeply divided into narrow, spine-tipped segments. The prickly, spine-tipped flower heads are relatively large and strikingly cream-colored, though they may occasionally have a slightly pinkish tint, yielding seeds with feathery bristles. Pitcher's thistle is unlikely to be easily confused with any other thistle species in Michigan, including both native and nonnative species, all of which can be distinguished by their deep pink flower heads. Pitcher's thistle are unlikely to co-occur with other thistles, as Pitcher's thistle only persist in good quality, open dunes habitat. Vegetatively, all other thistles in Michigan lack the deep blue-green color of Pitcher's thistle and its usually dense covering of white woolly hairs. 

Characteristic category

Habitat

Characteristics
Habitat

The Pitcher’s thistle is a native thistle that grows on the open sand dunes and low open beach ridges along the shorelines of Lakes Michigan, Superior, and Huron. It is now found in Indiana, Michigan, and Wisconsin and in Ontario Canada. Pitcher’s thistle was extirpated from Illinois but has been reintroduced in Lake County. It is most often found in near-shore plant communities but it can grow in all nonforested areas of a dune system.

 

Pitcher’s thistle is endemic to the beaches and grassland dunes of Lakes Michigan, Superior, and Huron . The majority of known sites of Cirsium pitcheri occur along the shores of Lake Michigan. The species ranges from the north shore of Lake Superior south to Indiana, and formerly occurred in northern Illinois, where it is has been experimentally reintroduced.

Coastal

The land near a shore.

Characteristic category

Food

Characteristics
Food

 

Geography

Characteristics
Range

The species ranges from the north shore of Lake Superior south to Indiana, and formerly occurred in northern Illinois, where it is has been experimentally reintroduced. Distribution of the species extends along the Lake Michigan shoreline in Wisconsin. In the east it ranges through northern Lake Huron to the Manitoulin Island archipelago and southern Georgian Bay in Ontario. Pitcher’s thistle extends as far south as Lambton County, Ontario, Canada on Lake Huron, as indicated by pre-1964 collections for two localities.

Launch Interactive Map

Timeline

Explore the information available for this taxon's timeline. You can select an event on the timeline to view more information, or cycle through the content available in the carousel below.

6 Items