Contains 12 accepted taxa overall.
Characteristics
Classification
Citation
CIRSIUM Miller, Gard. Dict. Abr., ed. 4. 1754.
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TYPE: Cirsium heterophyllum (Linnaeus) Hill (Carduus heterophyllus Linnaeus) Lectotypified by Britton & A. Brown, Ill. Fl. N. U.S., ed. 2. 3: 548. 1913.
Species
| Scientific Name | Common Name | Herbarium Specimens | Status | Photos |
|---|---|---|---|---|
| Cirsium altissimum | Tall Thistle | |||
| Cirsium carolinianum | Carolina Thistle, Spring Thistle | |||
| Cirsium discolor | Field Thistle | |||
| Cirsium horridulum var. horridulum | Common Yellow Thistle | |||
| Cirsium horridulum var. vittatum | Southern Yellow Thistle | |||
| Cirsium lecontei | LeConte's Thistle | |||
| Cirsium muticum | Swamp Thistle | |||
| Cirsium nuttallii | Coastal Tall Thistle | |||
| Cirsium pumilum | Pasture Thistle | |||
| Cirsium repandum | Sandhill Thistle | |||
| Cirsium virginianum | Virginia Thistle | |||
| Cirsium vulgare | Bull Thistle |
Identification Key
1. Stem armed with prickly, decurrent leaf bases; leaf blade upper surface covered with short, appressed bristles or prickles
1. Stem lacking prickly decurrent leaf bases or these inconspicuous; leaf blade upper surface usually lacking bristles or prickles
2
2. Heads directly subtended by a whorl of foliaceous prickly bracts
3
2. Heads not directly subtended by foliaceous bracts
5
3. Stems and involucres densely tomentose or arachnose
3. Stems and involucres glabrous to sparsely tomentose or arachnose
4
4. Leaves shallowly to deeply pinnatifid, main prickles 10-30 mm long
4. Leaves spinose-dentate to shallowly pinnatifid, main prickles mostly 5-10 mm long
5. Phyllary prickle 0-0.5 mm long
5. Phyllary spines 0.5-12 mm long
6
6. Leaf blade lower surface densely tomentose
7
6. Leaf blade lower surface arachnoid-villous, losely tomentose, to glabrate
8
7. Involucre (2)2.5-3.5(4) cm long; phyllaries without a glutinous ridge
7. Involucre 1.5-2.5 cm long; distal phyllaries with a medial glutinous ridge
8. Heads 1-5(10) per plant; involucre 2.5-4 cm long
8. Heads 5-40 per plant; involucre 1.5-2.5 cm long
Genus Synonyms
| Synonym | Full Citation | Basionym | Type |
|---|---|---|---|
| No synonyms found. | |||