Phragmites australis (Cav.) Trin. & Steudel.  

Perennial, rhizomatous, tall, stout reeds. Culms woody, hollow. Panicle large, plumose. Spikelets 2-10-flowered, disarticulating above the glumes and between the florets; rhachilla conspicuously long-hairy; glumes equal or unequal, thin; lemmas glabrous but surrounded by the long hairs of the rhachilla; lowest lemma staminate or sterile, the rest all bisexual, 3-nerved, caudate-acuminate; palea much shorter than the respective lemma. Stamens 3.

‏It includes 3 species of which one is found in Saudi Arabia.

‎‏Phragmites australis (Cav.) Trin. & Steudel, Nom. Bot. ed 2, 2:324 (1841); Bor in Towns., Guest & Al-Rawi, Fl. Iraq. 9:62 (1968); Bor in Rech. f., Fl. Iran 70:352 (1970); Clayton in Milne-Redhead & Polhill, Fl. Trop. East Afr. Gramineae: 117 (1970). Fig. 60.

‎‏English Name: Common reed, Ditch reed. Arabic Name: Qasab, Ghaab. قصب - غاب

‎‏= Arundo phragmites L., Sp. Pl. 1:81 (1753); A. australis Cav. in Anales Hist. Nat. Madrid 1:100 (1799); Phragmites communis Trin., Fund. Agrost 134 (1820); Trichoon phragmites (L.) Rendle, Cat. Afr. Pl. Welw. 2:218 (1899); Phragmites maxima (Forssk.) Blatter & McCann. Bombay Grasses 202 (1935), in part, based on Arundo maxima Forssk. (1775).

‎‏Type: Australia, Nee (MA).

‎‏A stout perennial, rhizomatous reed up to 3-4 meters tall. Leaf-blade firm usually 20-40 cm long or longer, 10-20 (-30) mm wide, acute. Panicle large,

‎‏25-50 cm long, up to 20 cm wide. Spikelets 10-15 (-18) mm long, 2-6-flowered, gaping; glumes unequal, the lower about 1/2 the length of the upper glume, the upper 4-6 mm long; lowest lemma 8-15 mm long, the fertile lemma 9-12 mm long.

‎‏Saudi Arabia: All regions in aquatic habitats, irrigation and drainage channels, etc. Doumatal Jandal, H. Heemstra 7289 (RIY-7981); Tarut Island, N. Munro (RIY-3812); Safwa Oasis, N. Longhitano (RIY-6415); Hofuf, M. Sharif (RIY-6413); Wadi Miyah, N. Munro (RIY-6412); Abqaiq, S. Abedin (RIY-9512); Al-Kharj, S. Chaudhary 6112, 12203 (RIY).

‎‏Distribution: Cosmopolitan.