 Flower of puncturevine (Caltrop, Tribulus terrestris, Tribulus lanuginosus, local name hasak) on a roadside in southern Qatar, February 11, 2014
 Puncturevine (Caltrop, Tribulus terrestris, Tribulus lanuginosus, local name hasak) in sand on roadside in southern Qatar, February 11, 2014
 Blooming puncturevine (Caltrop, Tribulus terrestris, Tribulus lanuginosus, local name hasak) on a roadside in southern Qatar, February 11, 2014
 Flower of puncturevine (Caltrop, Tribulus terrestris, Tribulus lanuginosus, local name hasak) in sand near a road to Saudi Arabia in southern Qatar, February 11, 2014
 Puncturevine (Caltrop, Tribulus terrestris, local name hasak) taken from Al Luqta area. Doha, Qatar, March 13, 2015
 Puncturevine (Caltrop, Tribulus terrestris) on roadside of Salwa Road, south-west from Doha. Qatar, April 23, 2014
 Puncturevine (caltrop, Tribulus terrestris) on a sidewalk of Al Diwan Street. Doha, Qatar, March 28, 2014
 Puncturevine (Caltrop, Tribulus terrestris) in a silty depression on roadside of a road to Zubara, area of Al Magdah farms. Northern Qatar, October 24, 2015
 Small yellow flower of puncturevine (Caltrop, Tribulus terrestris) in Old Baylor Park. Independence, Texas, September 6, 2009
 Puncturevine (Caltrop, Tribulus terrestris) with a yellow flower in Washington-on-the-Brazos State Historic Site. Washington, Texas, July 1, 2012
 Puncturevine (Caltrop, Tribulus terrestris) on Ferry Road in Washington-on-the-Brazos State Historic Site. Washington, Texas, June 28, 2014
 Puncturevine (Caltrop, Tribulus terrestris) on a path in TAMU Horticultural Gardens in Texas A and M University. College Station, Texas, August 1, 2014
 Fruit of Puncturevine (Caltrop, Tribulus terrestris) on a path in TAMU Horticultural Gardens in Texas A and M University. College Station, Texas, August 1, 2014
 Close up of Puncturevine (Caltrop, Tribulus terrestris) on a path in TAMU Horticultural Gardens in Texas A and M University. College Station, Texas, August 1, 2014
 Puncturevine (Caltrop, Tribulus terrestris) in Washington-on-the-Brazos State Historic Site. Washington, Texas, August 7, 2010
 Puncturevine (Caltrop, Tribulus terrestris) in Washington-on-the-Brazos State Historic Site. Washington, Texas, July 1, 2012
 Puncturevine (Caltrop, Tribulus terrestris) in Washington-on-the-Brazos State Historic Site. Washington, Texas, July 27, 2013
 Puncturevine (Caltrop, Tribulus terrestris) in Washington-on-the-Brazos State Historic Site. Washington, Texas, August 10, 2019
 Puncturevine (Caltrop, Tribulus terrestris) in Washington-on-the-Brazos State Historic Site. Washington, Texas, September 1, 2019
 Caltrop flower (puncturevine, Tribulus terrestris) in Washington-on-the-Brazos State Historic Site. Washington, Texas, September 1, 2012
 Flower of puncturevine (Caltrop, Tribulus terrestris) in Washington-on-the-Brazos State Historic Site. Washington, Texas, August 29, 2010
 Yellow flowers of Tribulus macropterus var. arabicus in sandy area in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 8, 2016
 Tribulus macropterus var. arabicus with yellow flowers on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 4, 2016
 Yellow flowers of Ochradenus baccatus (local names qardi, Qurdi) on a roadside of Abu Samra Road in southern Qatar, February 11, 2014
 Yellow flower of Tribulus macropterus var. arabicus on sand near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Tribulus macropterus var. arabicus with a yellow flower on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Large yellow flower of Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Yellow flower of Tribulus macropterus on roadside of Dukhan Highway. Ash-Shahaniyah, Qatar, December 4, 2015
 Knucklehead Weed (Sclerocephalus arabicus, Paronychia sclerocephala, local names hasak, thereisa) in sand near Trainah in southern Qatar, February 14, 2014
 Yellow flower of Tribulus macropterus var. arabicus in sandy area in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 8, 2016
 Knucklehead Weed (Sclerocephalus arabicus, Paronychia sclerocephala, local names hasak, thereisa) near a road to Sawda Natheel in southern Qatar, February 11, 2014
 Knucklehead Weed (Sclerocephalus arabicus, Paronychia sclerocephala, local names hasak, thereisa) near a road to Saudi Arabia in southern Qatar, February 11, 2014
 Large yellow flower of Tribulus macropterus var. arabicus in sand near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, January 22, 2016
 Tribulus macropterus var. arabicus with flowers in windblown sand in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 29, 2016
 Tribulus macropterus var. arabicus with flowers in sandy area in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 29, 2016
 Tribulus macropterus var. arabicus with flowers on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 4, 2016
 Solitary plant of Tribulus macropterus var. arabicus with flowers in windblown sand in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 29, 2016
 Desert plant Medicago laciniata (Medicago polymorpha, local names nafal abu hasak, hassak, jet barri) in sand near Trainah in southern Qatar, February 14, 2014
 Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Tribulus macropterus var. arabicus in bloom on sand near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Desert plant Medicago laciniata (Medicago polymorpha, local names nafal abu hasak, hassak, jet barri) near a road to Saudi Arabia in southern Qatar, February 11, 2014
 Desert plant Medicago laciniata (Medicago polymorpha, local names nafal abu hasak, hassak, jet barri) with seeds in sand near Trainah in southern Qatar, February 14, 2014
 Tribulus macropterus var. arabicus with a flower on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Blooming shoot of Tribulus macropterus var. arabicus on sand near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Blooming Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Desert plant Medicago laciniata (Medicago polymorpha, local names nafal abu hasak, hassak, jet barri) with seeds near a road to Sawda Natheel in southern Qatar, February 11, 2014
 Fruits of Tribulus macropterus(?) taken from a roadside of roadside of Salwa Road near Abu Nakhlah. Qatar, December 11, 2015
 Large flower of Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Tribulus macropterus var. arabicus with a large flower on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, February 26, 2016
 Flowers of Zilla spinosa (Bunias spinosa, local name shabram) on a roadside of Abu Samra Road in southern Qatar, February 11, 2014
 Dense flowers of Zilla spinosa (Bunias spinosa, local name shabram) on a roadside of Abu Samra Road in southern Qatar, February 11, 2014
 White flowers of Malva parviflora (Malva flexuosa, local name khubaiza) on a roadside of Abu Samra Road in southern Qatar, February 11, 2014
 Close up of flowers of Zilla spinosa (Bunias spinosa, local name shabram) on a roadside of Abu Samra Road in southern Qatar, February 11, 2014
 Yellow flower of a desert plant Zygophyllum simplex (Tetraena simplex, local names Daa, harm, hureim) in a roadside depression of Abu Samra Road in southern Qatar, February 11, 2014
 Tribulus macropterus on roadside of Dukhan Highway. Ash-Shahaniyah, Qatar, December 4, 2015
 Tribulus macropterus with fruits taken from a roadside of Dukhan Highway in Ash-Shahaniyah. Qatar, December 4, 2015
 Fruit of Tribulus macropterus taken from a roadside of Dukhan Highway in Ash-Shahaniyah. Qatar, December 4, 2015
 Violet flowers of Sand Spurry (Spergularia diandra, Arenaria diandra, Spergula diandra, local name degaygah) in a roadside depression of Abu Samra Road in southern Qatar, February 11, 2014
 Hairy fruit of Tribulus macropterus taken from a roadside of Dukhan Highway in Ash-Shahaniyah. Qatar, December 4, 2015
 Close up of Tribulus macropterus with fruits taken from a roadside of Dukhan Highway in Ash-Shahaniyah. Qatar, December 4, 2015
 Bladderdock (Rumex vesicarius, local name homeid) on roadside in southern Qatar, February 14, 2014
 Tribulus macropterus var. arabicus on sand in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 25, 2016
 Blooming Tribulus macropterus var. arabicus in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 8, 2016
 Fruits of Tribulus macropterus detached from the plant taken from a roadside of Dukhan Highway in Ash-Shahaniyah. Qatar, December 4, 2015
 Close up of a hairy fruit of Tribulus macropterus taken from a roadside of Dukhan Highway in Ash-Shahaniyah. Qatar, December 4, 2015
 Shoot of Tribulus macropterus with a flower and fruits taken from a roadside of Dukhan Highway in Ash-Shahaniyah. Qatar, December 4, 2015
 Alfalfa (Medicago sativa, local names jet, barseem) on roadside in southern Qatar, February 14, 2014
 Blooming Spergula fallax (local name degaygah) in a roadside depression in southern Qatar, February 11, 2014
 Tribulus macropterus var. arabicus in sandy area in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 29, 2016
 Tribulus macropterus var. arabicus on a hill slope in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 8, 2016
 Blooming plant of Tribulus macropterus var. arabicus in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 1, 2016
 Branch of Tribulus macropterus var. arabicus on sand in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 1, 2016
 Yellow flowers of Rhanterium epapposum (local name Arfaj) on roadside of Route 77 to Ras Laffan. Qatar, February 6, 2016
 Blooming Spergula fallax (local name degaygah) on a roadside of Abu Samra Road in southern Qatar, February 11, 2014
 Seedling of Tribulus macropterus var. arabicus in sand near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, January 22, 2016
 Tribulus macropterus var. arabicus on a slope of a limestone hill in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 29, 2016
 Blooming plant of Tribulus macropterus var. arabicus on sand in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 25, 2016
 Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 4, 2016
 Blooming Tribulus macropterus var. arabicus in sand near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, January 22, 2016
 Flower of Tribulus macropterus var. arabicus in sand near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, January 22, 2016
 Blooming plant of Tribulus macropterus var. arabicus in sandy area in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 29, 2016
 Seedling of Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, January 22, 2016
 Tribulus macropterus var. arabicus in flower on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 4, 2016
 Blooming Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 4, 2016
 Solitary plant of Tribulus macropterus var. arabicus in windblown sand in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 29, 2016
 Tribulus macropterus var. arabicus in sandy area below a limestone cliff in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 8, 2016
 Blooming plant of Tribulus macropterus var. arabicus on sand dunes in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 1, 2016
 Filago desertorum (local name quTeyna) with flowers in southern Qatar, February 14, 2014
 Tribulus pentandrus near Abu Nahlah Road, south from Doha. Qatar, March 5, 2014
 Blooming Tribulus macropterus var. arabicus in sandy area below a limestone cliff in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 8, 2016
 Blooming branch of Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 4, 2016
 Seedling of Tribulus macropterus var. arabicus emerging from sand in dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, January 22, 2016
 Young plant of Tribulus macropterus var. arabicus on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, January 22, 2016
 Fruits of Tribulus macropterus var. arabicus growing on sand dunes near the spring in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, March 4, 2016
 Tribulus macropterus var. arabicus on windblown sand at the foot of limestone cliffs in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 1, 2016
 Solitary blooming plant of Tribulus macropterus var. arabicus in windblown sand in Maszhabiya (Al Mashabiya) Reserve near Abu Samra. Southern Qatar, April 29, 2016
 Tribulus pentandrus with a flower taken from Abu Nahlah Road, south from Doha. Qatar, March 5, 2014
 Tribulus pentandrus with fruits taken from Abu Nahlah Road, south from Doha. Qatar, March 5, 2014
 Prickly Dock (Emex spinosa, Rumex spinosus, local names drs al ajooz, hanzab) on a roadside in southern Qatar, February 11, 2014
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