16.03   PHRAGMITES Adans.

REVISED TREATMENT. Please send comments to Mary Barkworth.
Kelly W. Allred

Plants perennial; rhizomatous or stoloniferous, often forming dense stands. Culms 1-4 m tall, 0.5-1.5 cm thick, leafy; internodes hollow. Leaves cauline, mostly glabrous; sheaths open; ligules membranous, ciliate; blades flat or folded. Inflorescences terminal, plumose panicles. Spikelets with 2-8 florets, weakly laterally compressed, lower 1-2 florets staminate, distal 1-2 florets rudimentary, remaining florets bisexual; rachilla internodes sericeous; disarticulation above the glumes and below the florets. Glumes unequal, shorter than the florets, 1-3-veined, glabrous; lower glumes much shorter than the upper glumes; calluses pilose, hairs 6-12 mm; lemmas 3-veined, glabrous, unawned; anthers 1-3. Caryopses rarely maturing. x = 12. Name from the Greek phragma, fence, alluding to its fencelike growth.

In the grass volumes of the Flora of North America, Phragmites was interpreted as a monotypic genus having a worldwide distribution. At that times, some taxonomists (e.g., Clayton 1970; Koyama 1987; Scholz and Bohling 2000) recognized 3-4 segregate species. Recent work has identified three different genotypes in North America (Saltonstall 2002) that preliminary data suggest may be morphologically distinct (see http://www.invasiveplants.net/). How these genotypes relate to the various segregate species that have been recognized is not yet known. In 2004, Saltonstall et al. formally recognized three subspecies in North America. A summary of their findings is presented after the species description. In
2010: Haines raised P. australis subsp. americanus Saltonstall et al. to specific rank as Phragmites americanus (Saltonstall et al.) A.Haines.

Phragmites karka is sometimes attributed to the Flora region. It supposedly differs from P. australis as shown below, but all the characters intergrade. For this reason, they are treated here as components of a single species.

1
Blades smooth on the abaxial surfaces, the apices filiform, flexible; rachilla hairs 6-10 mm long; upper glumes 5-10 mm long ..... P. australis
Blades scabrous on the abaxial surface, the apices attenuate, stiff; rachilla hairs 4-7 mm long; upper glumes 4-6 mm long ..... P. karka

Plants of Phragmites are similar in overall appearance to Arundo, but the latter has subequal glumes, a glabrous rachilla, and hairy lemmas. Vegetatively, plants of Arundo, but not those of Phragmites, have a wedge-shaped, light to dark brown area at the base of the blades. They also tend to have thicker rhizomes, thicker and taller culms, and wider leaves than Phragmites, but there is some overlap. Phragmites is much more widely distributed than Arundo in North America.


SELECTED REFERENCES Catling, P.M., G. Mitrow, L. Black, and S. Caribyn. 2004. Status of the alien race of common reed (Phragmites australis) in the Canadian maritime provinces. BEN (Botanical Electronic News) #324; Clayton, W.D. 1967. Studies in the Gramineae. XIV. Kew Bull. 21:111-117; Clayton, W.D. 1970. Flora of Tropical East Africa, Gramineae (Part 1). Crown Agents for Oversea Governments and Administrations, London, England. 176 pp.; H.E. Connor, M.I. Dawson, R.D. Keating, and L.S. Gill. 1998. Chromosome numbers of Phragmites australis (Arundineae:Gramineae) in New Zealand. New Zealand J. Bot. 36:465-469 [49-54]; Hocking, P.C., C.M. Finlayson, and A.J. Chick. 1983. The biology of Australian weeds. 12. Phragmites australis Trin. ex Steud. J. Austral. Inst. Agric. Sci. 49:123-132; Y. Ishi and Y. Kadono. 2000. Classification of two Phragmites species, P. australis and P. japonica, in Lake Biwa-the Yodo River system, Japan. Acta Phytotax. Geobot. 51:177-186; Koyama, T. 1987. Grassesof Japan and Its Neighboring Regions: An Identification Manual. Kodansha, Ltd., Tokyo, Japan. 370 pp.; Saltonstall, K. 2002. Cryptic invasion by a non-native genotype of the common reed, Phragmites australis, into North America. Proc. Natl. Acad. Sci. U.S.A. 99:2445-2449; Saltonstall, K., P.M. Peterson, and R. J. Soreng. 2004. Recognition of Phragmites autralis subsp. americanus (Poaceae: Arundinoideae) in North America: Evidence from morphological and genetic analyses. Sida 21:683-692; Scholz, H. and N. Böhling. 2000. Phragmites frutescens (Gramineae) re-visited: The discovery of an overlooked, woody grass in Greece, especially Crete. Willdenowia 30:251-261.


1.   Phragmites australis (Cav.) Trin. ex Steud.
Common Reed, Phragmite Commun

Culms 1-4 m tall, 0.5-1.5 cm thick, erect. Ligules about 1 mm; blades 15-40 cm long, 2-4 cm wide, long-acuminate, disarticulating from the sheath at maturity. Panicles 15-35 cm long, 8-20 cm wide, ovoid to lanceoloid, often purplish when young, straw-colored at maturity. Spikelets with 3-10 florets; rachilla hairs (4)6-10 mm. Lower glumes 3-7 mm; upper glumes (4)5-10 mm; lemmas 8-15 mm, glabrous, linear, margins somewhat inrolled, apices long-acuminate; paleas 3-4 mm, membranous; anthers 1.5-2 mm, purplish; styles persistent. Caryopses 2-3 mm, rarely maturing. 2n = 36, 42, 44, 46, 48, 49-54 (Connor et al. 1998), 72, 84, 96, 120.

Phragmites australis grows in wet or muddy ground along waterways, in saline or freshwater marshes, and in sloughs throughout North America. Its tall, leafy, often persistent culms and plumose panicles make it one of our easier species to recognize. In Florida, Neyraudia reynaudiana is sometimes mistaken for P. australis, but the former has glabrous internodes and pilose lemmas. There are three subspecies in North America north of Mexico, one of which is invasive.

Phragmites australis is one of the most widely distributed flowering plants, growing in most temperate and tropical regions of the world, spreading quickly by rhizomes. Once established, it is difficult to eradicate. Its uses include thatching, lattices, arrow shafts, construction boards, mats, and erosion control, and it was used in the past to make cigarettes and superior pen quills.

1
Ligules 1-1.7 mm long; lower glumes 3-6.5 mm long; upper glumes 5.5-11 mm long; lemmas 8-13.5 mm long; leaf sheaths deciduous; culms exposed in winter, smooth, shiny; plants rarely forming a monoculture ..... subsp. americanus
Ligules 0.4-0.9 mm long; lower glumes 2.5-5 mm long; upper glumes 4.5-7.5 mm long; lemmas 7.5-12 mm long; leaf sheaths not deciduous; culms not exposed in winter, smooth and shiny, or ridged and not shiny; plants often forming a monoculture (2)
2
Culms smooth and shiny; plants of southern California, Arizona, New Mexico, and Texas to Florida, and throughout Mexico and Central America ..... var. berlandieri
Culms ridged and not shiny; plants of southern Canada (from British Columbia to Quebec) south through the continental United States ..... subsp. autralis

Phragmites australis subsp. americanus Saltonstall et al. is native to North America. It grows across much of Canada and, in the United States, from New England and the mid-Atlantic states across to the Pacific coast and into the southwest.

Phragmites australis subsp. berlandieri (E. Fourn.) Saltonstall & Hauber is the strain that grows from the Atlantic coast of Florida, around the Gulf of Mexico, southewstern Arizona, northern Mexico, and south into Central and South America. it is not clear whether it is native or introduced. Some taxonomists treat it as P. karka, which was described from India.

Phragmites australis subsp. australis (Invasive). The name Pragmites autralis, and hence the name Phragmites australis subsp. australis, is based on plants collected from what is now called Sydney, Autralia. They are the same strain as is present in Europe. On that basis, the invasive strain should be called P. australis subsp. australis or P. australis s.s. - if Haines' pomotion of subsp. americanus to species rank is accepted. For additional information, see the invasive plants network site and their page for distinguishing the invasive strain.