The species is described as widespread within the Hajar Mountains (Jongbloed et al. 2003) and occurs to at least c. 1,525 m in the Ru'us al-Jibal (Feulner 2011). However, this species is considered to be introduced to the UAE (Norton et al. 2009). Globally, it occurs across Europe and western Russia, the Sahara, the Mediterranean region, the Arabian Peninsula, and east to Pakistan and western India (Board of Trustees, RBG Kew 2019). GRIN (2019) excludes the Arabian Peninsula from the native distribution.

Within the UAE, this species was collected close to Liwa in the south of the country (Böer 1998). Globally, this species is native to both the temperate and subtropical realms (Board of Trustees, RBG Kew 2019).

This species is present in the United Arab Emirates from multiple records: within the Ra's al-Khaimah Emirate it is known from Diftah, southeast of Masafi, at 350 m asl (Miller and Cope 1996, Jongbloed et al. 2003, Rothfels et al. 2012). It also occurs at Jebel Hafeet (Sakkir and Brown 2014). The species is considered to be widespread throughout the Hajar Mountains (Jongbloed et al. 2003). Adiantum capillus-veneris is considered to grow at lower elevations, having not been found above c. 500 m in the Ru'us al-Jibal (Feulner 2011). This species has a sub-cosmopolitan distribution, occurring on all continents except the Antarctic, including temperate and tropical Asia, Macaronesia, throughout Africa, including Madagascar and the Mascarene Islands, Australia (where it is apparently considered to be native), New Zealand (where it is considered to be introduced) and the Americas from Canada south to Venezuela. In the Arabian Peninsula this species is known from Saudi Arabia (El-Olayan 2006, Sharawy and Alshammari 2009), Oman (Radcliffe-Smith 1980, Miller and Cope 1996, Pickering and Patzelt 2008, Rothfels et al. 2012), Yemen including Socotra (Kilian et al. 2002, Miller and Morris 2004), Bahrain (Miller and Cope 1996), United Arab Emirates (Miller and Cope 1996, Jongbloed et al. 2003). Although not widely reported, it is widespread throughout mountainous regions of the peninsula, occurring up to 3,000 m asl.

Within the UAE this species occurs in urban areas along the Arabian Gulf coast (Jongbloed et al. 2003). Sakkir et al. (2017) state that it is present on off-shore islands of Abu Dhabi. The Sharjah Seedbank & Herbarium and RBG Kew seed survey data hold records of this species from Al Ain city, and from the southern part of the Hajar Mountain range in the UAE; the identity and origin of these records need confirmation. Globally, the native range of this species spans across Africa and the eastern Mediterranean to the Arabian Peninsula and Iraq (Board of Trustees, RBG Kew 2019).

This species is locally common along the Arabian Gulf coast in suitable habitat in Abu Dhabi Emirate (Al Mehairbi et al. 2019) and has also been recorded from the Hatta pools (Jongbloed et al. 2003), although the continued presence of some coastal subpopulations requires confirmation due to extensive coastal development. Feulner (2011) recorded the species from coastal parts of northern Ras al-Khaimah. There are also records from the western slopes of the Hajar Mountains (Al Qasheesh Dam, Ras al-Khaimah; Sharjah Seedbank & Herbarium) and from the east coast at Kalba (1994, <a href=""http://data.rbge.org.uk/herb/E00398627"">RBGE Herbarium</a>); the latter record at least requires confirmation, and may no longer be extant. The species has a wide distribution in the tropics and subtropics, including Africa, southern Europe, the Americas, Australia and parts of Asia (Board of Trustees, RBG Kew 2018).

In the UAE, the species is widespread in the Hajar Mountains, along the east coast, and opportunistically elsewhere, including along the Arabian Gulf coast and the offshore islands (Sakkir et al. 2017), within irrigated areas (Jongbloed et al. 2003). It is found in lawns and golf courses as well as in mangrove forests (western Abu Dhabi) with fresh water supply from nearby irrigated lawns (Jongbloed et al. 2003). The species is now present throughout Africa, temperate and tropical Asia, Australasia and tropical America (Cook 1996), it has an almost pan-global distribution in the southern hemisphere (Board of Trustees, RBG Kew 2019). The species is considered to have originated in the Americas, but to have undergone natural dispersal from the America to Africa then to Australasia (Gross et al. 2017). However, it has also undergone human-mediated dispersal, which has obscured the origin of some populations (Gross et al. 2017); the origin of the species in the UAE can not be confirmed, but we consider it here to be occurring naturally in the country.

This species is found at scattered locations in the eastern UAE (Jongbloed et al. 2003), and from a single locality (an improved hillside spring adjacent to a small terraced plantation) in the Ru'us al-Jibal (Feulner 2011). It has also been found at Wadi Al Ain in addition to being recorded from Abu Dhabi Island. The native distribution of this species is the Americas according to Barkley et al. (2006), Plants of the World Online (Board of Trustees, RBG Kew 2018) and GRIN (2019). However, CABI (2019) consider the species to be native to Asia.

Within the UAE, it has been recorded from the dam and freshwater lake at Khor Fakkan, on the east coast of the country (Böer and Chaudhary 1999). However, it is thought that records of this species may have been misidentified and may in fact be individuals of P. nodosus instead. This species is listed as an introduced landscape plants by MoCCaE (O. Al Shamsi pers. comm. 2018). Globally, the native range of this species spans from the temperate Northern Hemisphere to the Philippines (Board of Trustees, RBG Kew 2019).

Within the Hajar Mountains in the UAE, it is considered to be widespread (Jongbloed et al. 2003). Globally, this species occurs from the south and eastern Mediterranean, through to the Arabian Peninsula and on to Afghanistan (Board of Trustees, RBG Kew 2019).

In the UAE, Jongbloed et al. (2003) reported a small number of isolated localities in coastal or near-coastal areas of the Ajman, Dubai and Abu Dhabi emirates. More recent records suggest a more frequent and widespread distribution, and Karim and Dhakeel (2006) give the distribution as Abu Dhabi (e.g., Sila, Tarif), Dubai, Fujairah, and Umm al-Qaiwain. In Ra's al-Khaimah, Feulner (2011) reported the species from, or adjacent to, salt marshes north of Rams and Llewellyn-Smith (2011) recorded the species at the Khor Hulaylah coastal wetland complex. Sakkir and Brown (2014) found the species at Jebel Hafeet, but comment that the species has been introduced to the area through human disturbance and benefits from irrigated agriculture. Globally, this species occurs throughout the Mediterranean, east through western and central Asia, to India and south to northern and central Africa, as well as South America, Australia and parts of Southeast Asia. There is no information on whether some of these populations may be non-native. In the Arabian Peninsula, this species occurs throughout coastal areas in the region, and locally inland in Oman.