Flodman’s thistle

(Cirsium flodmanii)

               
Conservation Status

IUCN Red List

not yet assessed

Flodman’s thistle

NatureServe

N5? - Secure

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

FAC - Facultative

Midwest

FAC - Facultative

Northcentral & Northeast

FACU - Facultative upland

Nativity

Native

 
Occurrence

Common

 
Habitat

Moderately moist. Meadows, pastures, fields, and railroads. Full sun.

 
Flowering

June to September

     
Flower Color

Purple

     
Height

12 to 32

     

Identification

This is an erect, perennial forb. It can be 12 to 55 tall but usually reaches no more than 32 in height. New plants rise usually on a single stem from short-lived, horizontal, creeping roots and eventually develop a taproot.

The stems are erect and slender, unbranched or with just a a few ascending branches above the middle. They are not winged and do not have spines. They are densely covered with short, white, matted or tangled, soft, woolly hairs (tomentose). As the plant ages the stem remains tomentose.

This plant first appears as a rosette of basal leaves. The basal leaves are inversely lance-shaped to narrowly elliptic in outline, up to 16 long, and up to 4 wide. They taper at the base to a winged leaf stalk. They are deeply lobed (pinnatifid), sometimes cut to the midrib. The lobes are triangular lance-shaped, sharply pointed, and seldom more than ¼ wide. The upper surface of the leaf blade is light green or grayish-green and thinly tomentose at first, becoming hairless or nearly hairless with age. The lower surface is densely white tomentose, and remains so as it ages. The margins are coarsely toothed, spiny, and often rolled under. The first (outer) basal leaves may be unlobed but with spiny margins. The inner leaves become increasingly lobed. Basal leaves are usually absent at flowering time.

Stem leaves are similar, alternate, 1½ to 16 long, and to 4 wide. Lower stem leaves are deeply pinnately divided into long triangular lobes are on winged leaf stalks. The leaves become smaller and shorter stalked but no less divided as they ascend the stem. Upper leaves are well developed and stalkless.

The inflorescence is a single flower head at the end of the stem and each branch tip. Sometimes a cluster of a few heads will rise from an upper leaf axil. The flower heads are stalkless or on up to 2 long stalks which elevate them above the uppermost leaves. They are not subtended by a ring of spiny, leaf-like bracts.

The whorl of bracts at the base of the flower head (involucre) is egg-shaped to broadly bell-shaped, ¾ to 1 long, 1 to 1 wide, thinly covered with a few cobwebby hairs. They are rounded but not indented at the base. The bracts of the involucre have a 1 16 to long, straw-colored spine at the tip, and a dark central zone and a light-colored, sticky ridge. The pale ridge is often called a racing stripe and is an identifying character of many thistles.

The flower heads are about 1 wide with numerous purple, tubular, disk flowers.

The fruit is a light brown, to 3 16 long achene (cypsela). The cypsela has a conspicuous yellow collar near the tip and a tuft of white hairs at the tip.

 
Similar
Species

Field thistle (Cirsium discolor) is a much taller plant, 36 to 84 in height. The stems become hairless or almost hairless with age. The upper leaf surface may be hairy but is never tomentose. The flower head is subtended by a ring of spiny, leaf-like bracts. The flower head is larger, 1½ to 2 wide. The collar on the cypsela is straw colored.


Distribution Distribution Map  

Sources: 2, 3, 4, 5, 7, 28.


Comments

 


Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Carduoideae

 

Tribe:

Cynareae

 

Subtribe:

Carduinae

 
Synonyms

Cirsium oblanceolatum

Cirsium nebraskense var. discissum

 
Common
Names

Flodman’s thistle

prairie thistle

woolly thistle


 

 

 

 

 

 

 

Glossary

Achene

A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed entirely from the wall of the superior ovary, does not split open at maturity, but relies on decay or predation to release the contents.

 

Axil

The upper angle where a branch, stem, leaf stalk, or vein diverges.

 

Bract

Modified leaf at the base of a flower stalk or flower cluster.

 

Cypsela

A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed from the wall of the inferior ovary and also from other tissues derived from the receptacle or hypanthium, does not split open at maturity, but relies on decay or predation to release the contents.

 

Involucre

A whorl of bracts beneath or surrounding a flower or flower cluster.

 

Pinnatifid

Deeply cut, more than half way to the midrib but not to the midrib, into lobes that are spaced out along the midrib; the lobes do not form separate leaflets.

 

Tomentose

Densely covered with short, soft, matted or tangled, woolly, usually white or silvery hairs.

 

Wing

A thin, flat, membranous, usually transparent appendage on the margin of a structure.

       

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Inflorescence

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Flower Head

  Flodman’s thistle    
       

Basal Leaves

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Stem

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About

Native perennial spreading by horizontal roots, leaves with green glabrous upper surfaces and white woolly lower surfaces, corollas white to purple, common to open dry vegetation including high-native-cover Wyoming big sagebrush steppe. This species is very similar to Cirsium canovirens (=Cirsium subniveum), which in Montana occurs at higher elevations and is a tap-rooted single-stemmed biennial inhabiting well-managed rangeland.

 
     

 

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