The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

chardon de Flodman, Flodman's thistle, prairie thistle

slough thistle

Habit Perennials 30–140 cm; horizontal runner roots that produce root sprouts. Annuals or biennials, (60–)100–300 cm; taprooted.
Stems

1–several, erect, gray- or white-tomentose;

branches 0–few, ascending.

usually 1, erect, stout, (hollow, 2–10 cm diam. at base), openly branched distally, thinly arachnoid, villous with jointed trichomes, at least proximally.

Leaves

blades oblong-oblanceolate to narrowly elliptic, 4–40 × 1–10 cm, bases usually not decurrent, finely spiny-toothed and undivided to coarsely toothed or deeply pinnatifid, lobes broadly triangular to linear-lanceolate, often revolute-margined, main spines 1–7 mm, abaxial faces white-tomentose, adaxial faces green, thinly tomentose, ± glabrate;

basal usually absent or withered at flowering, winged petiolate;

principal cauline proximally winged-petiolate, distally sessile, well distributed, gradually reduced, bases usually not decurrent;

distal cauline well developed.

blades elliptic to broadly oblanceolate, 15–70 × 30–150+ cm, flat, pinnatifid 1/2–2/3 distance to midvein, larger usually with broad sinuses, lobes broad, few lobed or dentate, main spines 3–8 mm, abaxial faces gray-tomentose, adaxial thinly arachnoid-tomentose, sometimes midveins with jointed trichomes;

basal present or withered at flowering, winged-petiolate;

principal cauline sessile, progressively reduced distally, bases clasping or short-decurrent 1–2 cm;

distal cauline reduced, becoming bractlike, sometimes spinier than proximal.

Peduncles

0–5 cm (elevated above distal leaves).

0–15 cm.

Involucres

ovoid to broadly campanulate, 2–3.5 × 2.5–3.5 cm, thinly arachnoid.

ovoid to campanulate, 1.5–3 × 1.5–3 cm, ± glabrous.

Corollas

purple (white), 23–36 mm, tubes 12–15 mm, throats 6–8.5 mm, lobes 5–9 mm;

style tips 4–7 mm.

pale rose-purple (white), 19–26 mm, tubes 9–12 mm, throats 4–6 mm, lobes 5–9 mm;

style tips 3.5–4.5 mm.

Phyllaries

in 7–12 series, strongly imbricate, greenish with subapical darker central zone, ovate or lanceolate (outer) to linear (inner), abaxial faces with prominent glutinous ridge;

outer and middle entire, bodies appressed, entire, acute, spines abruptly spreading, slender, 2–4 mm;

apices of inner spreading, flexuous, narrow, flattened, finely serrulate, ± scabrous.

in 5–7 series, weakly unequal, dark green to brownish, lanceolate (outer) to linear (inner), abaxial faces without (or with very obscure) glutinous ridge;

outer and middle appressed or apices spreading, at least outer irregularly spiny-fringed, finely serrulate, spines slender, 3–5 mm;

apices of inner erect, abaxial faces gray-tomentose, ± twisted.

Heads

erect, borne singly and terminal on main stem and branches, or few in corymbiform arrays from distal axils (not subtended by ring of spiny-margined bracts).

1–several at branch tips, closely subtended by clustered leafy bracts or not, collectively forming open, corymbiform or paniculiform arrays.

Cypselae

light brown, 3–5 mm, apical collars stramineous, 0.5–1 mm;

pappi (white or tawny) 20–30 mm.

dark brown, 5–5.5 mm, collars narrow, ± stramineous;

pappi 15–20 mm.

2n

= 22, 24.

= 32.

Cirsium flodmanii

Cirsium crassicaule

Phenology Flowering summer (Jun–Sep). Flowering spring (Apr–Jun).
Habitat Tallgrass, mixedgrass, shortgrass prairies, meadows, pastures, often in damp soil Freshwater marshes, canal banks
Elevation 100–2400 m (300–7900 ft) 5–100 m (0–300 ft)
Distribution
from FNA
CO; IA; IL; KS; MI; MN; MT; ND; NE; SD; WI; WY; AB; MB; ON; QC; SK
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Cirsium flodmanii ranges from Saskatchewan and Alberta south through the northern Great Plains and intermountain valleys of Montana and Wyoming to northeastern Colorado and east through the prairies to Minnesota and Iowa, and in widely scattered locations eastward to northern Illinois, southern Wisconsin, southern Ontario, and southern Quebec. It is known to hybridize with C. muticum and C. undulatum. Hybrids between C. flodmanii and C. undulatum are highly sterile with numerous meiotic irregularities (S. Dabydeen 1987).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Cirsium crassicaule is known only from a few sites in the San Joaquin Valley. Some populations are threatened by habitat modification and development pressures.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 19, p. 120. FNA vol. 19, p. 132.
Parent taxa Asteraceae > tribe Cardueae > Cirsium Asteraceae > tribe Cardueae > Cirsium
Sibling taxa
C. altissimum, C. andersonii, C. andrewsii, C. arizonicum, C. arvense, C. barnebyi, C. brevifolium, C. brevistylum, C. canescens, C. carolinianum, C. ciliolatum, C. clavatum, C. crassicaule, C. cymosum, C. discolor, C. douglasii, C. drummondii, C. eatonii, C. edule, C. engelmannii, C. foliosum, C. fontinale, C. grahamii, C. helenioides, C. hookerianum, C. horridulum, C. hydrophilum, C. inamoenum, C. joannae, C. kamtschaticum, C. lecontei, C. longistylum, C. mohavense, C. muticum, C. neomexicanum, C. nuttallii, C. occidentale, C. ochrocentrum, C. ownbeyi, C. palustre, C. parryi, C. perplexans, C. pitcheri, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. texanum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
C. altissimum, C. andersonii, C. andrewsii, C. arizonicum, C. arvense, C. barnebyi, C. brevifolium, C. brevistylum, C. canescens, C. carolinianum, C. ciliolatum, C. clavatum, C. cymosum, C. discolor, C. douglasii, C. drummondii, C. eatonii, C. edule, C. engelmannii, C. flodmanii, C. foliosum, C. fontinale, C. grahamii, C. helenioides, C. hookerianum, C. horridulum, C. hydrophilum, C. inamoenum, C. joannae, C. kamtschaticum, C. lecontei, C. longistylum, C. mohavense, C. muticum, C. neomexicanum, C. nuttallii, C. occidentale, C. ochrocentrum, C. ownbeyi, C. palustre, C. parryi, C. perplexans, C. pitcheri, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. texanum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
Synonyms Carduus flodmanii, C. oblanceolatum Carduus crassicaulis
Name authority (Rydberg) Arthur: Torreya 12: 34. (1912) (Greene) Jepson: Fl. W. Calif., 506. (1901)
Web links