Introduced and assessed as invasive in the lower 48 states
iNaturalist's volunteer curators list it as introduced in their Ohio checklist.
US-RIIS assesses a species as invasive when it causes, or is likely to cause, harm there, or is at least locally abundant and harmful ecologically, economically, or to health.
Season shown in 3 of Ohio's 88 counties. Explore Ohio
No result yet (18)
Recorded, too few records for a result (59)
Recorded, season not shown (8)
Season shown (3)
Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files, 1:500,000. Show as a table
Counties as a table
Bull Thistle by Ohio county: records and mapped range
County
Records
Adams County
Recorded, too few records for a result
Allen County
Recorded, too few records for a result
Ashland County
Recorded, too few records for a result
Ashtabula County
Recorded, too few records for a result
Athens County
67 · Season shown
Auglaize County
Recorded, too few records for a result
Belmont County
Recorded, too few records for a result
Brown County
No qualifying records yet
Butler County
31 · Recorded, season not shown
Carroll County
Recorded, too few records for a result
Champaign County
No qualifying records yet
Clark County
Recorded, too few records for a result
Clermont County
Recorded, too few records for a result
Clinton County
Recorded, too few records for a result
Columbiana County
Recorded, too few records for a result
Coshocton County
Recorded, too few records for a result
Crawford County
Recorded, too few records for a result
Cuyahoga County
127 · Season shown
Darke County
Recorded, too few records for a result
Defiance County
Recorded, too few records for a result
Delaware County
Recorded, too few records for a result
Erie County
Recorded, too few records for a result
Fairfield County
Recorded, too few records for a result
Fayette County
No qualifying records yet
Franklin County
98 · Season shown
Fulton County
No qualifying records yet
Gallia County
Recorded, too few records for a result
Geauga County
Recorded, too few records for a result
Greene County
Recorded, too few records for a result
Guernsey County
Recorded, too few records for a result
Hamilton County
44 · Recorded, season not shown
Hancock County
Recorded, too few records for a result
Hardin County
No qualifying records yet
Harrison County
Recorded, too few records for a result
Henry County
Recorded, too few records for a result
Highland County
Recorded, too few records for a result
Hocking County
Recorded, too few records for a result
Holmes County
Recorded, too few records for a result
Huron County
No qualifying records yet
Jackson County
Recorded, too few records for a result
Jefferson County
Recorded, too few records for a result
Knox County
Recorded, too few records for a result
Lake County
Recorded, too few records for a result
Lawrence County
No qualifying records yet
Licking County
Recorded, too few records for a result
Logan County
Recorded, too few records for a result
Lorain County
23 · Recorded, season not shown
Lucas County
48 · Recorded, season not shown
Madison County
Recorded, too few records for a result
Mahoning County
Recorded, too few records for a result
Marion County
Recorded, too few records for a result
Medina County
Recorded, too few records for a result
Meigs County
No qualifying records yet
Mercer County
Recorded, too few records for a result
Miami County
Recorded, too few records for a result
Monroe County
Recorded, too few records for a result
Montgomery County
Recorded, too few records for a result
Morgan County
No qualifying records yet
Morrow County
Recorded, too few records for a result
Muskingum County
Recorded, too few records for a result
Noble County
No qualifying records yet
Ottawa County
Recorded, too few records for a result
Paulding County
No qualifying records yet
Perry County
No qualifying records yet
Pickaway County
Recorded, too few records for a result
Pike County
No qualifying records yet
Portage County
25 · Recorded, season not shown
Preble County
Recorded, too few records for a result
Putnam County
No qualifying records yet
Richland County
Recorded, too few records for a result
Ross County
Recorded, too few records for a result
Sandusky County
Recorded, too few records for a result
Scioto County
Recorded, too few records for a result
Seneca County
No qualifying records yet
Shelby County
Recorded, too few records for a result
Stark County
35 · Recorded, season not shown
Summit County
97 · Recorded, season not shown
Trumbull County
Recorded, too few records for a result
Tuscarawas County
Recorded, too few records for a result
Union County
Recorded, too few records for a result
Van Wert County
No qualifying records yet
Vinton County
No qualifying records yet
Warren County
Recorded, too few records for a result
Washington County
Recorded, too few records for a result
Wayne County
Recorded, too few records for a result
Williams County
Recorded, too few records for a result
Wood County
98 · Recorded, season not shown
Wyandot County
No qualifying records yet
No mapped range from the range source used, the USGS Gap Analysis Project, which maps land vertebrates only.
Season
When it is recorded
In Portage County
Not enough evidence
The weeks are still too uncertain to show a season. Based on 25 records in 7 of the 10 years from 2016 to 2025, above the minimum of 20 records from 5 different years.
JanFebMarAprMayJunJulAugSepOctNovDec
Show over the bars
Recording in Portage County · records of all species each week, 31,804 in all
Records per week from 25 records in 7 of the 10 years from 2016 to 2025. Shows when people recorded it, not a season or how common it is.
Show as a table
Records of Bull Thistle in Portage County each week, and records of all species
Week
Records of Bull Thistle
Years recorded
Records of all species
Jan 4–10
0
0
44
Jan 11–17
0
0
56
Jan 18–24
0
0
31
Jan 25–31
0
0
67
Feb 1–7
0
0
66
Feb 8–14
0
0
74
Feb 15–21
0
0
72
Feb 22–28
0
0
80
Mar 1–7
0
0
109
Mar 8–14
0
0
146
Mar 15–21
0
0
152
Mar 22–28
0
0
140
Mar 29 – Apr 4
0
0
277
Apr 5–11
0
0
451
Apr 12–18
0
0
648
Apr 19–25
0
0
641
Apr 26 – May 2
2
2
849
May 3–9
0
0
1,174
May 10–16
0
0
788
May 17–23
1
1
1,091
May 24–30
0
0
753
May 31 – Jun 6
1
1
782
Jun 7–13
2
2
1,242
Jun 14–20
1
1
1,568
Jun 21–27
1
1
1,383
Jun 28 – Jul 4
0
0
1,344
Jul 5–11
0
0
1,357
Jul 12–18
1
1
1,310
Jul 19–25
2
2
1,431
Jul 26 – Aug 1
1
1
1,439
Aug 2–8
2
2
1,037
Aug 9–15
1
1
1,056
Aug 16–22
1
1
1,145
Aug 23–29
0
0
911
Aug 30 – Sep 5
2
2
930
Sep 6–12
0
0
986
Sep 13–19
2
2
974
Sep 20–26
0
0
1,199
Sep 27 – Oct 3
2
2
985
Oct 4–10
0
0
516
Oct 11–17
1
1
417
Oct 18–24
0
0
435
Oct 25–31
2
2
401
Nov 1–7
0
0
278
Nov 8–14
0
0
251
Nov 15–21
0
0
228
Nov 22–28
0
0
130
Nov 29 – Dec 5
0
0
82
Dec 6–12
0
0
79
Dec 13–19
0
0
69
Dec 20–26
0
0
53
Dec 27 – Jan 2
0
0
77
Reported in flower
Only 8 records here show flowers, too few to show a flowering season. One needs at least 20 records from 5 different years.
Reported in fruit
Only 3 records here show fruit, too few to show a fruiting season. One needs at least 20 records from 5 different years.
In Ohio
Mid-April to early October, middle week Aug 9–15
Middle week · Aug 9–15
This week · Nov 8–14
JanFebMarAprMayJunJulAugSepOctNovDec
Show over the bars
Recording in Ohio · records of all species each week, 1,691,199 in all
Records per week from 1,281 records in 10 of the 10 years from 2016 to 2025. Shows when people recorded it, not how common it is. The grey bars show how many records of all species were made here each week, so you can see when recording itself was high or low; the season is not adjusted by them.
Recorded on 772 dates. Latest record: November 2025.
Show as a table
Records of Bull Thistle in Ohio each week, and records of all species
Week
Records of Bull Thistle
Years recorded
Records of all species
Jan 4–10
1
1
6,211
Jan 11–17
1
1
5,146
Jan 18–24
0
0
4,645
Jan 25–31
1
1
4,698
Feb 1–7
2
2
6,023
Feb 8–14
1
1
5,888
Feb 15–21
3
3
5,436
Feb 22–28
0
0
6,846
Mar 1–7
4
4
8,321
Mar 8–14
2
2
10,384
Mar 15–21
5
3
12,620
Mar 22–28
8
6
13,949
Mar 29 – Apr 4
16
5
19,661
Apr 5–11
17
6
26,860
Apr 12–18
19
6
39,925
Apr 19–25
18
6
41,623
Apr 26 – May 2
41
9
56,391
May 3–9
21
6
52,952
May 10–16
13
8
53,785
May 17–23
26
6
57,698
May 24–30
19
7
54,651
May 31 – Jun 6
22
7
53,099
Jun 7–13
21
7
53,700
Jun 14–20
17
8
56,625
Jun 21–27
19
7
55,361
Jun 28 – Jul 4
28
7
58,477
Jul 5–11
19
9
61,336
Jul 12–18
27
8
64,722
Jul 19–25
53
10
69,753
Jul 26 – Aug 1
73
10
59,416
Aug 2–8
85
10
59,712
Aug 9–15
94
10
55,994
Aug 16–22
70
8
54,328
Aug 23–29
53
10
51,772
Aug 30 – Sep 5
59
8
57,167
Sep 6–12
71
10
59,075
Sep 13–19
71
9
54,543
Sep 20–26
65
9
45,860
Sep 27 – Oct 3
98
8
43,180
Oct 4–10
53
7
37,841
Oct 11–17
21
7
30,824
Oct 18–24
10
7
21,156
Oct 25–31
12
7
19,021
Nov 1–7
7
4
14,172
Nov 8–14
5
3
12,621
Nov 15–21
4
3
7,965
Nov 22–28
2
2
8,136
Nov 29 – Dec 5
0
0
6,083
Dec 6–12
1
1
6,004
Dec 13–19
2
2
5,423
Dec 20–26
0
0
5,661
Dec 27 – Jan 2
1
1
8,459
Reported in flower
Usually reported in flower mid-July to early October, middle week Aug 16–22.
From 269 records that show flowers. Not every photo of a plant in flower is marked as flowering, so this shows when people reported it in flower, not when it flowers.
Reported in fruit
No fruiting season shown here. Most records come from a single year, so a season is not shown yet.
What these results show
These results show when people recorded a species, not when or where it occurs. Missing weeks and low counts do not mean absence or scarcity, and counts are not abundance. Contributed records reflect where, when and what people chose to observe.
field thistleCirsium discolorOften confused in Ohio: 130 identifications in Ohio named one where the other was meant
creeping thistleCirsium arvenseOften confused in Ohio: 34 identifications in Ohio named one where the other was meant
wild teaselDipsacus fullonumOften confused in Ohio: 11 identifications in Ohio named one where the other was meant
musk thistleCarduus nutans432 identifications worldwide named one where the other was meant
Tall ThistleCirsium altissimum119 identifications worldwide named one where the other was meant
From iNaturalist’s similar-species counts, refreshed monthly: confusions in Ohio first, then worldwide. Only species with an Ohio result are listed.
Land cover where it is recorded
Land cover
Its recordsAll Ohio records
Developed
70%49%
Farmland
17%11%
Forest
9%31%
Wetland
2%5%
Grassland and shrub
1%0.9%
Open water
0.7%3%
Barren
0.1%0.6%
From 820 records placed within 100 m, beside all Ohio records placed the same way. People record where they go, so this shows where records come from, not where the species lives. Land cover: USGS Annual NLCD, 2025 (opens in a new tab)
Sources
Where these results come from
Records from iNaturalist research-grade observations and expert-identified GBIF datasets, CC0, CC BY and CC BY-NC. Sources
Seasons use the published method and its evidence thresholds. Methods
A spreadsheet (CSV) with a link to each record, on iNaturalist or GBIF. Records whose location was hidden by the observer or the source are counted but not linked.
