This species appears to occur in scattered localities throughout the UAE (Jongbloed et al. 2003). The species is a significant agricultural weed (CABI 2019) and is listed as an introduced landscape plant by MoCCaE, and its origin in the UAE perhaps requires confirmation. The species is not cited for the UAE by Al Mehairbi et al. (2019). Globally, the native range of this species spans from Macaronesia and the Mediterranean to the Himalayas and Eritrea (Board of Trustees, RBG Kew 2019), and it has been very widely introduced.

The distribution of this species in the UAE is not well understood. Feulner (2016) records the species from the Wadi Wurayah National Park buffer zone in the upper parts of Wadi Siji and Feulner (2014) records the species from northeast facing cliffs along the summit ridge of Jebel Qitab, from Jebel Masafi. It is known from a single site in the Ru'us al-Jibal on a cliff-face close to a spring ('Ayn as-Sih in Oman) at 470 m elevation (Feulner 2011). The species also occurs at cultivated sites elsewhere in the UAE. Globally, the native range of this species spans across northern Africa to Caucasus and to the Indian subcontinent (Board of Trustees, RBG Kew 2019). Although Plants of the World Online lists the UAE as a native country of occurrence, there is very little available information on this species within the country, including detailed distribution data.

The species has been recorded from Al Ain (Dubai; Karim 1993) and from Al Dhaid (Sharjah) in the UAE. Globally, the native range of this species spans across Socotra, the Arabian Peninsula, Turkey and on to China and the western Himalayas (Board of Trustees, RBG Kew 2019). Although Plants of the World Online lists the UAE as a native country of occurrence for this species, there seems to be little available information on this plant within the UAE, and Kameswara Rao (2013) lists only Saudi Arabia for the Arabian Peninsula.

Sharjah Seed Bank and Herbarium holds just two known localities for this species in the UAE, in Dubai Emirate (on the edge of Dubai city) and Fujairah Emirate (near Khor Fakkan city). Al Mehairbi et al. (2019) report the species from Abu Dhabi Island in urban areas. Globally, the native range of this species spans across the Old World (Board of Trustees, RBG Kew 2019). The species has been very widely introduced to the Americas and Australasia.

This species is widespread across the northern part of the UAE (Jongbloed et al. 2003), however it is not clear if this refers instead to D. sanguinalis (MEW 2010). The global distribution of this species extends from the Mediterranean to Central Asia and Malesia (Board of Trustees, RBG Kew 2019).

UAE records of this species are from F. Karim (G.R. Feulner pers. comm. 2019); from plantations and mountains near Masafi and Dibba. The species was Not Evaluated for the 2010 Red Data Book (MEW 2010) as, at the time, its presence was known from a single mention by Cope (2007) and identity of these records requires confirmation (S. Ghazanfar pers. comm. 2018). It is also unclear whether this species is native or introduced to the UAE. Globally, the species has a circum-Mediterranean distribution, extending eastwards to Central Asia; occurs in the UAE, but only doubtfully present in Saudi Arabia (Board of Trustees, RBG Kew 2019).

Within the UAE, it is known to occur in the Ru'us al-Jibal (Feulner 2011), north of Jebel Mebrah (Jebel Yibir) and a small number of other jebels. In this area it is considered to preferentially grow at higher elevations, with records from 1,250 m to 1,650 m (G.R. Feulner, in litt, MEW 2010, Feulner 2011). Globally, the native range of this species spans across the Mediterranean, northern Africa and to Afghanistan, including Sudan (Board of Trustees, RBG Kew 2019). Plants of the World Online does not list the UAE as a native country of occurrence for this species (Board of Trustees, RBG Kew 2019).

The distribution of this species within the UAE is uncertain, as a result of confusion with other members of the genus. It is considered present in the country by RBG Edinburgh (A. Forrest pers. comm. 2018), and the RBG Edinburgh Herbarium holds two specimens; from <a href=""http://data.rbge.org.uk/herb/E00209886"">Qarn Naswa </a>and <a href=""http://data.rbge.org.uk/herb/E00209881"">Jebel Milaya (Meleiha)</a>, both originally determined as C. conglomeratus. The native range of the species is from Cape Verde, West tropical Africa, through the Arabian Peninsula to north-western India and the western Indian Ocean (Väre and Kukkonen 2005, Board of Trustees, RBG Kew 2019).

Within the UAE, this species is only known from two localities; a plantation at Lulayah near Khor Fakkan (Western 1987) on the east coast, and from Al Ain near Jebel Hafeet (Jongbloed et al. 2003). Continued presence at both sites requires verification, given the age of the records and the extensive commercial and urban development that has occurred at both localities in recent years. Globally, this species occurs in Central and East Africa, through the Arabian Peninsula, to Pakistan and India (Board of Trustees, RBG Kew 2018).

This species is described as being 'widespread' within the UAE and growing within plantations (Jongbloed et al. 2003). In addition, R. Western recorded this species from Abu Dhabi. The global distribution of this species is uncertain. GRIN (2019) considers it to be native to West Asia (Afghanistan, Iran, Iraq), Central Asia, western China and the Caucasus, introduced and naturalised elsewhere. Plants of the World Online (Board of Trustees, RBG Kew 2019), gives the native distribution as northern Africa, the Arabian Peninsula and central Asia. In the Arabian Peninsula, this species is known from Saudi Arabia, United Arab Emirates, Qatar and Kuwait (Miller and Cope 1996). There don't appear to be any current specimens collected from the UAE within the Royal Botanic Garden Edinburgh's Herbarium collection (RGBE Edinburgh 2019).