Identification
 Lower stem and leaves S. Garske - GLIFWC |
 Early season stalk S. Garske - GLIFWC |
 Early season flowerheads S. Garske - GLIFWC |
 Flower and seedheads S. Garske - GLIFWC |
 Stem with sharp spines S. Garske - GLIFWC |
 Big branching plant S. Garske - GLIFWC |
 Flowering plants S. Garske - GLIFWC |
 Several plants in wetland S. Garske - GLIFWC |
Habitat & Invaded Sites
 Roadside ditch S. Garske - GLIFWC |
 Dense colony in roadside channel S. Garske - GLIFWC |
 Colony in natural wetland S. Garske - GLIFWC |
 Invaded natural wetland S. Garske - GLIFWC |
Look-Alikes (Native)
Swamp thistle, Cirsium muticum
 Rosettes of swamp thistle (left, native) and Eurasian marsh thistle (right, introduced) S. Garske - GLIFWC |
 Swamp thistle leaf S. Garske - GLIFWC |
 Swamp thistle stem and leaf bases S. Garske - GLIFWC |
 Swamp thistle - lower stem and leaves S. Garske - GLIFWC |
 Swamp thistle flowerheads S. Garske - GLIFWC |
 Swamp thistle - flower and seedheads S. Garske - GLIFWC |
 Swamp thistle - flowering plant S. Garske - GLIFWC |
 Swamp thistle in flower S. Garske - GLIFWC |
Look-Alikes (Non-native)
Canada thistle, Cirsium arvense
 Canada thistle S. Garske - GLIFWC |
 Canada thistle on shoreline S. Garske - GLIFWC |
 Canada thistle leaf S. Garske - GLIFWC |
 Canada thistle patch S. Garske - GLIFWC |
Bull thistle, Cirsium vulgare
 Bull thistle along road S. Garske - GLIFWC |
 Bull thistle S. Garske - GLIFWC |
 Bull thistle in flower S. Garske - GLIFWC |
 Bull thistle flowerheads S. Garske - GLIFWC |