Flodman’s thistle

Flodman’s thistle 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 ⅜″ 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 1⅜″ long, 1″ to 1⅜″ 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 ⅛″ 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, ⅛″ 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.

12″ to 32″

Purple

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.

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

June to September

Sources

2, 3, 4, 5, 7, 24, 28, 29, 30.

iNaturalist has sightings in Crow Wing and McCleod Counties (light green on the map) that appear to be either misidentifications or unidentifiable to species.

Native

Common

Cardueae is a synonym of the tribe name. Cynareae was published first and has precedence. Nevertheless, most sources use the name Cardueae for the tribe.

Regal Fritillary...

A male Regal Fritillary on Flodman’s Thistle. Seen it on July 10, 2024. Beautiful butterfly. Hopefully more conservation programs will become available to help with the declining number. I never see many of them on any given year since I first noticed a regal fritillary between 5-6 yrs. ago but they declined in number in the few areas I seen any. The male regals life is pretty much done.

Hadn’t seen any so imagine the few that were around have died off as it is that time of year for the male. Females haven’t seen any lately but haven’t been out much since the weather has been wet. I seen a few earlier in August but only a few. They gestate so to speak and need cover and rest etc. developing all the eggs. That is why they aren’t seen as much as some other species of butterflies.

… Thistle...

Noticed this stand of … thistle blooming. … They were maybe 2 to 3 feet tall. Several species of bees and insects seemed attracted to the flowers.

Funny little Bumble Bee...

Coming in for a landing on one of the flowering thistle at Frenchman’s Bluff SNA July 2024. This is a closer image of thistle out of the same group of thistle in the previous image sent of the several standing straight and fairly tall group. Funny little bumble bee.

Plant

Inflorescence

Flower head

Basal leaves

Stem leaves

Stem

Cirsium flodmanii
Matt Lavin

Location: Norman Co., Mn.

This 2024 season male regal numbers are down from last season in an area I usually see some. I’m not sure about females yet as they tend to remain in the dense vegetation until a little closer to the egg laying period which isn’t too far away really. I had seen a couple females back in July toward the last week but none since though I haven’t been out for about a week or so.

Also Jessica Peterson informed me the regals have been proposed for federal listing as threatened. So perhaps we will see some conservation actions directed at regals in the near future. I think that would be a good thing.

This female was down in some dense vegetation at a SNA in my area. I caught a little of her bluish sheen on the one wing. The light has to catch the wing areas just right for it to show. Early in their lives regals are a beautiful and a true native prairie butterfly. Real interesting species too.

Dan W. Andree
July 2024

Location: Frenchman’s Bluff SNA

Noticed this stand of … thistle blooming. … They were maybe 2 to 3 feet tall. Several species of bees and insects seemed attracted to the flowers.

Location: Cass County