This is the most common species of seagrass in the UAE. In the Arabian Gulf, there are large areas of this species in inshore areas and around most, if not all, islands in Abu Dhabi Emirate, from the Abu Dhabi Islands to Ra's Hanjurah, with a total area of c.55 km² estimated and representing c. 60% of seagrass bed content (EAD 2017); seagrass was found to be much more abundant in eastern Abu Dhabi, with the highest densities occurring north of Abu Dhabi Island around Al Samaliyah Island (EAD 2008). There is estimated to be around 4,000 km² of this species within Abu Dhabi Emirate (H.S. Das pers. comm. 2019). The species also occurs in Dubai Emirate, with records of extensive seagrass beds containing this species in the Jebel Ali area, particularly between Ras Hasyan and Ras Ghantoot, with their distribution primarily linked to areas of unconsolidated, deep sand (CBD 2016), and offshore from Jumeirah Beach. The species occurs eastwards to at least Umm Al Quwain. This species has a wide Indo-Pacific distribution. In the Pacific, it is found in southern Japan, Taiwan, the Philippines, Malaysia, Indonesia, throughout the Gulf of Thailand and along the coast of Vietnam and southern China. It occurs throughout insular Southeast Asia, northeast to the Northern Mariana Islands, Micronesia, and southeast to the Fiji Islands, as well as across northern Australia and the Great Barrier Reef. In the Indian Ocean, it is found from Geographe Bay in Western Australia extending across the Timor Sea, the south coast of Indonesia, and to the Andaman Sea and extending around the Bay of Bengal and around India to the Malabar Coast. It ranges from the Persian Gulf to the Red Sea, south to the east coast of South Africa to Madagascar and the islands of the western Indian Ocean.

Within the UAE, this species is known to occur along the Arabian Gulf coast (Phillips et al. 2002). The maximum AOO of this species is estimated to be under 2,000 km², incorporating the area of this species found in Abu Dhabi and Ras al-Khaimah (H.S. Das pers. comm. 2019). Due to the occurrence of multiple seagrass meadows along the UAE coastline, there are estimated to be greater than ten threat-based locations. The native range of this species encompasses Egypt to India and the West Indian Ocean (Board of Trustees, RBG Kew 2019).

Within the United Arab Emirates, this species has been recorded from urban areas of Dubai (Gardner 2013, Burriel-Carranza et al. in press) and Abu Dhabi, where it is considered to be introduced. It occurs from sea level to 100 m asl. This species is native to tropical Asia (possibly Sri Lanka or southern India), but is invasive in many parts of the world and is now known from approximately 84 countries worldwide (Lever 2003, Wallach 2009). This cosmopolitan distribution includes Old World tropical and subtropical regions, with encroachment into the northern Hemisphere of the New World and adjacent temperate areas (Wallach 1999, 2009). It is found at a wide range of elevations.

This species occurs throughout UAE waters. Globally, it is widespread in the Indo-West Pacific (Talwar and Jhingran 1991, al Sakaff and Esseen 1999, Bijukumar and Sushama 2000, Almatar et al. 2004, Rahman and Akhter 2009, B. Russell and Y. Iwatsuki pers. comm. 2013).

Within the UAE, this species has been recently recorded from the Ru'us al-Jibal (Feulner 2011). It is thought to generally grow at high elevations within this area, between 1,200 and 1,350 m (Feulner 2011). Globally, this species' native range spans from Tunisia to Afghanistan (Board of Trustees, RBG Kew 2019).

Avena barbata occurs in the Ru'us al-Jibal mountains in the north of the UAE (Jongbloed et al. 2003, Feulner 2011). Within this area, it has been recorded from one confirmed locality in the UAE at 900 m elevation, above bedrock on a ridge. A second record at 1,500 m elevation (Feulner 2011) may not be within the UAE. The origin and distribution of the species in the UAE requires confirmation; it may be native or be present here as a result of natural introduction, or may have been introduced alongside agriculture. Globally, this species occurs in northern, middle, east, south-east and south-west Europe, temperate Asia, Macaronesia, northern Africa and the Indian Subcontinent, and is naturalized in the Azores, Australia and the Americas (Duarte et al. 2011, Board of Trustees, RBG Kew 2018).

In UAE waters, this species does not occur in the Arabian Gulf (B. Collette pers. comm. 2013), but may occur on the Sea of Oman coast, though records are not yet confirmed. Elsewhere, it is cosmopolitan in warm waters (Collette and Aadland 1996).

This species occurs throughout UAE waters. Globally, itis widely distributed in the Indo-West Pacific.

This species occurs throughout UAE waters. Elsewhere, it is cosmopolitan in warm waters (Collette and Aadland 1996, Robertson and Allen 2015).

This species occurs throughout UAE waters. Globally, itis widely distributed in the tropical and sub-tropical Indo-West Pacific (Williams 1963, Collette 1984, Randall 1995, Rohit et al. 2012).