 Top view of Bull thistle (Cirsium horridulum) on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Yellow thistle (Bull thistle, Cirsium horridulum) on Richards Loop Trail in Sam Houston National Forest. Texas, April 13, 2024
 Yellow thistle (Bull thistle, Cirsium horridulum) on Lone Star Trail in Sam Houston National Forest, near Huntsville. Texas, April 8, 2018
 Blooming yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 5, 2019
 Bull thistle (Cirsium horridulum) on a forest clearing on Caney Creek Trail (Little Lake Creek Loop Trail) in Sam Houston National Forest north from Montgomery. Texas, April 11, 2021
 Yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 6, 2022
 Yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 18, 2022
 Blooming yellow thistle (Bull thistle, Cirsium horridulum) in Bastrop State Park. Bastrop, Texas, April 25, 2021
 Yellow flower of bull thistle (Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 18, 2022
 Yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 5, 2018
 Yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 5, 2019
 Yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 12, 2024
 Flower of yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 5, 2019
 Flower bud of yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 11, 2018
 Flower bud of yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, April 14, 2019
 Yellow thistle (Bull thistle, Cirsium horridulum) on a recently built pipeline in Lick Creek Park. College Station, Texas, April 12, 2021
 Flower of yellow thistle (Bull thistle, Cirsium horridulum) with a bronze beetle in Lick Creek Park. College Station, Texas, April 5, 2019
 Metallic beetles in yellow thistle (Bull thistle, Cirsium horridulum) on a pipeline right-of-way in Lick Creek Park. College Station, Texas, April 12, 2021
 Thistle (Cirsium) on Richards Loop Trail in Sam Houston National Forest. Texas, April 21, 2022
 Yellow thistle (Bull thistle, Cirsium horridulum) on Post Oak Trail in Lick Creek Park. College Station, Texas, March 26, 2019
 Flower bud of yellow thistle (Bull thistle, Cirsium horridulum) on Post Oak Trail in Lick Creek Park. College Station, Texas, March 26, 2019
 Yellow spiny thistle (Bull thistle, Cirsium horridulum) at sunrise in Lake Bryan Park. Bryan, Texas, April 13, 2010
 Yellow thistle (Bull thistle, Cirsium horridulum) on a forest opening over a sewage line in Lick Creek Park. College Station, Texas, March 31, 2023
 Yellow thistle (Bull thistle, Cirsium horridulum) on Whitman Road, near Washington. Texas, March 22, 2009
 Winter rosette of bull thistle (Cirsium horridulum) with freeze in Lick Creek Park. College Station, Texas, January 3, 2022
 Yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, March 31, 2024
 Seeds of yellow thistle (Bull thistle, Cirsium horridulum) on sewage line right-of-way in Lick Creek Park. College Station, Texas, May 2, 2023
 Yellow thistle (Bull thistle, Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, March 24, 2021
 Rosette of leaves of yellow thistle (Bull thistle, Cirsium horridulum) in Lick Creek Park. College Station, Texas, January 10, 2024
 Arrangement of seeds of yellow thistle (Bull thistle, Cirsium horridulum) on sewage line right-of-way in Lick Creek Park. College Station, Texas, May 2, 2023
 Fluffy seeds of yellow thistle (Bull thistle, Cirsium horridulum) on sewage line right-of-way in Lick Creek Park. College Station, Texas, May 2, 2023
 Immature seed head of yellow thistle (Bull thistle, Cirsium horridulum) on sewage line right-of-way in Lick Creek Park. College Station, Texas, May 2, 2023
 Basal leaves of yellow thistle (Bull thistle, Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, February 25, 2021
 Winter rosette of yellow thistle (Bull thistle, Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, March 11, 2021
 Winter rosette of yellow thistle (Bull thistle, Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, February 25, 2021
 Large thorny rosette of yellow thistle (Bull thistle, Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, February 25, 2021
 Bull thistle (Cirsium horridulum) in Bastrop State Park. Bastrop, Texas, April 25, 2021
 Leaves of bull thistle (Cirsium horridulum) in area of a former pond in Washington-on-the-Brazos State Historic Site. Washington, Texas, February 20, 2022
 Yellow thistle (Bull thistle, Cirsium horridulum)(?) in Bastrop State Park. Bastrop, Texas, March 17, 2018
 Yellow thistle (Bull thistle, Cirsium horridulum) in Lake Bryan Park. Bryan, Texas, March 20, 2010.
 Rosette of leaves of bull thistle (Cirsium horridulum) in area of a former pond in Washington-on-the-Brazos State Historic Site. Washington, Texas, February 20, 2022
 Yellow thistle (Bull thistle, Cirsium horridulum)(?) on mulch in a tree utilization site in Bastrop State Park. Bastrop, Texas, March 17, 2018
 Fluffy seeds of bull thistle (Cirsium horridulum) in Lick Creek Park. College Station, Texas, May 7, 2018
 Bull thistle (Cirsium horridulum) at Lake Somerville Trailway near Birch Creek Unit of Somerville Lake State Park. Texas, April 5, 2020
 Opening flower of bull thistle (Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, March 24, 2021
 Yellow flowers of bull thistle (Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, March 24, 2021
 Large flower bud of bull thistle (Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, March 24, 2021
 Rosette and yellow flowers of bull thistle (Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, March 24, 2021
 Leaves of bull thistle (Cirsium horridulum) in ultraviolet light on a sewage line right of way in Lick Creek Park. College Station, Texas, November 15, 2024
 Bull thistle (Cirsium horridulum)(?) on a golf course on campus of Texas A and M University. College Station, Texas, February 14, 2021
 Rosette of bull thistle (Cirsium horridulum)(?) on a golf course on campus of Texas A and M University. College Station, Texas, February 14, 2021
 Icy rosettes of bull thistle (Cirsium horridulum)(?) on a golf course on campus of Texas A and M University. College Station, Texas, February 14, 2021
 Rosette of basal leaves of bull thistle (Cirsium horridulum) in ultraviolet light on a sewage line right of way in Lick Creek Park. College Station, Texas, November 15, 2024
 Side view of a large yellow flower of bull thistle (Cirsium horridulum) on a pipeline clearing in Lick Creek Park. College Station, Texas, March 24, 2021
 Basal leaves of bull thistle (Cirsium horridulum) when exposed to regular daylight as well as when illuminated by a 365 nm ultraviolet (UV-A) blacklight on a sewage line right of way in Lick Creek Park. College Station, Texas, November 15, 2024
 Thorny leaves of bull thistle (Cirsium horridulum) when exposed to regular daylight as well as when illuminated by a 365 nm ultraviolet (UV-A) blacklight on a sewage line right of way in Lick Creek Park. College Station, Texas, November 15, 2024
 Winter rosette of bull thistle (Cirsium horridulum) when exposed to regular daylight as well as when illuminated by a 365 nm ultraviolet (UV-A) blacklight on a sewage line right of way in Lick Creek Park. College Station, Texas, November 15, 2024
 Smaller rosette of basal leaves of bull thistle (Cirsium horridulum) when exposed to regular daylight as well as when illuminated by a 365 nm ultraviolet (UV-A) blacklight on a sewage line right of way in Lick Creek Park. College Station, Texas, November 15, 2024
 Central area of rosette of basal leaves of bull thistle (Cirsium horridulum) when exposed to regular daylight as well as when illuminated by a 365 nm ultraviolet (UV-A) blacklight on a sewage line right of way in Lick Creek Park. College Station, Texas, November 15, 2024
 Blooming hawthorn on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Blooming hawthorn on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Blooming dewberry on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Blooming poison ivy (Toxicodendron radicans) on Richards Loop Trail in Sam Houston National Forest. Texas, April 21, 2022
 Blooming woolly-white (Hymenopappus) on Forest Service Road 203 near Richards Loop Trail in Sam Houston National Forest. Texas, April 21, 2022
 Blooming woolly-white (Hymenopappus) with a flower beetle on Richards Loop Trail in Sam Houston National Forest. Texas, April 21, 2022
 Bull nettle (Cnidoscolus texanus) on Richards Loop Trail in Sam Houston National Forest. Texas, April 21, 2024
 Blooming mistflower (Eupatorium coelestinum) on Richards Loop Trail in Sam Houston National Forest. Texas, October 1, 2022
 Summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 27, 2022
 Summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 22, 2022
 Flower of summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 27, 2022
 Bumblebee on a summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 27, 2022
 Flower of summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 22, 2022
 Flower bud of summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 13, 2022
 Flower of summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 13, 2022
 Unopened flower of summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 13, 2022
 Opening flower of summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 22, 2022
 Flower head of summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, June 22, 2022
 Blooming Macartney rose (Rosa bracteata) on Richards Loop Trail in Sam Houston National Forest. Texas, April 28, 2020
 Blooming summer-blooming thistle (Cirsium engelmannii) in Lick Creek Park. College Station, Texas, July 3, 2014
 Blooming woolly-white (Hymenopappus artemisiaefolius) on road FS203 near Richards Loop Trail in Sam Houston National Forest. Texas, April 13, 2024
 Blooming coralbean (Erythrina herbacea) on Sand Branch Loop Trail in Sam Houston National Forest near Montgomery. Texas, April 30, 2022
 Blooming hyssop skullcap (Scutellaria integrifolia) on Sand Branch Loop Trail in Sam Houston National Forest near Montgomery. Texas, April 30, 2022
 Blooming hyssop skullcap (Scutellaria integrifolia) on Sand Branch Loop Trail in Sam Houston National Forest near Montgomery. Texas, April 30, 2022
 Blooming thistle (Cirsium) in Washington-on-the-Brazos State Historic Site. Washington, Texas, April 13, 2023
 Shoot of oak on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Rosette of leaves of thistle (Cirsium) in a pine forest on Caney Creek section of Lone Star Hiking Trail in Sam Houston National Forest near Huntsville, Texas, May 19, 2018
 Blooming Rock-rose (frostweed, sunrose, Helianthemum carolinianum) in Sam Houston National Forest on Little Lake Creek Loop Trail. Richards, Texas, April 4, 2010.
 Shoot of sweetgum on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Shoot of beautyberry on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Young leaves of an oak on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Young leaves of oak on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Downy phlox (Phlox pilosa) blooming over young oak on Richards Loop Trail in Sam Houston National Forest. Texas, April 13, 2024
 Downy phlox (Phlox pilosa) blooming over young pine on Richards Loop Trail in Sam Houston National Forest. Texas, April 13, 2024
 Young leaves of hickory on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Pink phlox flower on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Yellow Coreopsis flower on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Young leaves of beautyberry on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Back lit flowers of dewberry on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
 Back lit young leaves of an oak on Richards Loop Trail in Sam Houston National Forest. Texas, April 9, 2022
|