Cladium mariscus (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Vegetable
Fuel
Ornamental
Auxiliary plant
Fibre
Climate change

Cladium mariscus (L.) Pohl

Protologue: Tent. Fl. Bohem. 1: 32 (1809).

Family: Cyperaceae

Chromosome number: 2n = 36

Synonyms

• Cladium jamaicense Crantz (1766).

Vernacular names

• Sawgrass, Jamaica sawgrass, swamp sawgrass, fen sedge, great fen sedge (En).
• Marisque (Fr).

Origin and geographic distribution

Cladium mariscus is distributed throughout the tropical and temperate regions of the world. In tropical Africa it is recorded from West, Central, East and southern Africa and from the Indian Ocean islands, but it is unclear in which countries exactly.

Uses

The stems and leaves are used for thatching. In Uganda, for instance, they are considered excellent material for this purpose. In Hawaii the leaves are used as tying material. In Romania and Malaysia the stems and leaves are used in the manufacture of paper products. The interior portion of the rhizome was traditionally used by indigenous North Americans as surface material for baskets.

In certain areas of the United Kingdom sawgrass leaves were traditionally harvested for thatching and for fuel. Minor uses of the leaves included covering bricks as they air-dried before kiln-drying, bedding for domestic animals, and strewing on thoroughfares or in public buildings as a temporary floor covering. Drainage channels were filled with sawgrass and covered with topsoil to serve as hollow drains. The plant is unpalatable and offers little nutrition for animals, but in the United Kingdom a mixture of sawgrass and grasses was sometimes cut from mixed-species swamps and fed to animals.

Cladium mariscus swamps are important stores of carbon in the form of deep organic peat soils, originating from years of build-up of decomposing plant litter. Cladium mariscus is planted as an ornamental.

Production and international trade

Widespread cutting and use of sawgrass leaves is recorded only from the United Kingdom. The standard unit is the bunch, which has a circumference of c. 70 cm upon cutting (this diminishes as the leaves dry), measured where the bunch is tied, 30 cm from the bottom. The leaves in the bunch vary in length with maturity at cutting, though modern thatchers prefer a length of 105 cm.

Properties

The flexibility of the leaves makes them a good material for covering the ridges of roofs thatched with other, more rigid materials such as reeds. The seeds contain an alkaloid.

Description

Robust, perennial sedge up to 5 m tall, with thick, erect, woody rhizome emitting stolons covered with imbricate scales 2–4 cm long; stems erect, up to 3 m tall, rounded, glabrous, hollow except at the nodes. Leaves inserted at the stem base and along the stem, 3-ranked; sheath tubular, disintegrating into fibres; ligule absent; blade linear, up to 225 cm × 28 mm, apex attenuate, margin sharply serrate. Inflorescence a terminal, compressed panicle (20–)30–90 cm × 5–15 cm, composed of secondary inflorescences inserted at each node in the axil of a long, sheathing bract; secondary inflorescence with numerous clusters of (1–)2–7(–10) spikelets. Spikelets sessile or almost so, lanceolate, ellipsoid or ovoid, 2–6 mm long, pale brown to red-brown, 2(–3)-flowered; glumes 5–7, spirally arranged, ovate, 2–3.5 mm long, obtuse, concave, brown, usually the 3–5 basal ones empty and the next one containing a bisexual flower setting fruit, the uppermost one male; perianth absent; stamens 2(–3); stigmas 2–3. Fruit a broadly ovoid or obovoid nutlet up to 3.5 mm long, apex attenuate, rugulose above, pale brown.

Other botanical information

Within Cladium mariscus various subspecies have been distinguished, but these taxonomic divisions are mainly geographical and the botanical differences are not always clear. The main subspecies are subsp. mariscus of Europe and Asia, subsp. jamaicense (Crantz) Kükenthal of the Western Hemisphere, Hawaii and Africa, and subsp. intermedium Kükenthal of Australia. Cladium mariscus subsp. jamaicense is sometimes considered a separate species: Cladium jamaicense Crantz. subsp. mariscus (‘thatching sedge’), occurring in more temperate regions, is a first-class thatching material. A thorough revision of the genus is needed.

Anatomy

Air spaces run vertically through the interior of the leaves, separated periodically by horizontal septa. Vascular bundles also run vertically through the leaves, and consist of xylem and phloem surrounded by and separated from one another by fibre bundles. Fibre strands also occur independently running vertically through the leaf.

Growth and development

Natural reproduction is principally from rhizomes, which occur 10–20 cm below the surface of seasonally-flooded soils. In permanently-flooded locations sawgrass forms elevated clumps, and rhizomes occur above the sediment surface. Leaf growth is favoured by warm temperatures and occurs at night, as it is inhibited by direct sunlight. Leaves can elongate at rates higher than 15 cm per week under warm conditions with ample moisture. Sawgrass stands produce seed, which is dispersed by water or birds. Seeds have low viability, and seedlings are sensitive to drying-out as well as to flooding. After flowering and seed set, the stem and its associated leaves and rhizome die and decay rapidly. Sometimes shoots never flower, and they continue vegetative growth for years before senescing.

Cladium mariscus is also able to reproduce vegetatively by pseudo-vivipary, i.e. the production on the parent plant of adventitious buds that are capable of development into new individuals in association with floret production in inflorescences. Cladium mariscus follows the C₃ photosynthetic pathway.

Ecology

Cladium mariscus occurs in the margins of lakes, pools, swamps and fens, particularly in sites with good nutrient availability. It usually occurs in shallow freshwater wetlands in warm regions, but it also tolerates brackish water and cool periods. It forms floating mats in deep water. In East Africa it occurs at 1000–2300 m altitude. In southern Africa it occurs in ‘dambo’ wetlands (natural ecosystems occupying shallow, waterlogged depressions at or near the head of drainage networks). Cladium mariscus thrives on deep organic soils that are flooded between 6 and 9 months of the year or longer. The ideal water depth is from 15 cm belowground to 40 cm aboveground. The plant tolerates a pH range of 4.5–8.6. It is a weed of rice fields.

Cladium mariscus is often the dominant species where it occurs, forming monospecific stands. However, when water level or duration of flooding changes, sawgrass is replaced by other species. The same happens with increased inflow of nutrients or brackish water. Sawgrass evolved under conditions of periodic natural fires, which spread quickly through dense sawgrass stands, burning dead litter and living leaves to a uniform height of a few centimetres above water level. Without periodic fire a thick layer of leaf debris builds up, suppressing plant vigour. Sawgrass regenerates rapidly from its rhizomes after fire, because the rhizomes are submerged in water or in contact with moist soil, and hence protected from the intense heat. However, severe fires under dry conditions burn all the way down to the soil and kill rhizomes, in which case regeneration is slow and sawgrass is outcompeted by other successional species. In British sawgrass swamps regular mowing maintained a dense stand of sawgrass, and in the absence of mowing the swamps gave way to other vegetation, namely peat bog or woodland. Conversely, digging peat from sawgrass bogs in Britain was occasionally shown to favour sawgrass, as the species regenerated rapidly in the lowered soil level.

Propagation and planting

Swamps of Cladium mariscus are natural ecosystems and are not planted. However, sawgrass is sometimes planted as a landscaping plant. In this case, the plant is usually grown from seed, probably because seed is easier to handle and transport than rhizomes and plantlets. The 1000-seed weight is 2.2–2.6 g. Seeds germinate best in soil that is saturated but not inundated, but even under good conditions germination rates of only 30–42% have been recorded. Initial plant growth and survival rates are also better in saturated than in inundated soil.

Management

Sawgrass swamps are naturally-occurring, although humans increasingly manage aspects of them. The water table can be maintained at a level to favour Cladium mariscus, and prescribed burning or harvesting serves to eliminate plant debris and maintain health of the sawgrass population.

Harvesting

In the United Kingdom sawgrass is harvested on a cycle of 3–5 years. More frequent harvesting leads to a decrease in plant density, whereas longer intervals allow accumulation of dead leaves and growth of woody species. Evidence from the subtropical Florida Everglades indicates that removal of plant matter (in this case by burning) is best done every 3–10 years.

Harvesters must wear heavy clothes to protect their arms, hands, and legs from the sharp sawtooth edges of the leaves. Sawgrass can be harvested at any time of the year, as ground conditions permit, though the United Kingdom it was traditionally harvested in spring or early summer.

Yield

Yields from British sawgrass swamps traditionally ranged from 1500–4500 bunches per hectare, cut every four years. In the Florida Everglades the annual aboveground production was estimated at 26 t/ha.

Genetic resources

Cladium mariscus is distributed widely throughout the world, and its diverse modes of sexual and vegetative propagation ensure that it is at little risk of extinction or genetic erosion. However, local populations of sawgrass may be threatened with genetic erosion or even elimination due to destruction of wetlands. In the case of British sawgrass swamps, decreased use of the plant has led to decreased harvesting of the swamps, which has allowed invasion of the swamps by other species.

Breeding

No breeding programmes of Cladium mariscus are known to exist.

Prospects

Few uses of Cladium mariscus are documented for tropical Africa. Its widest expanses are in the subtropical Everglades swamp in the United States, and most recorded uses are from the United Kingdom. The regions of Africa where Cladium mariscus is present could benefit by adopting certain British uses of the plant, such as for providing thatching material and fuel. In its areas of occurrence outside of Africa local populations are threatened by the management and mismanagement of the wetlands where they occur. Increased inflows of nutrients and pollutants, cultivation, and wetland drainage and diversion of freshwater sources (which both contribute to encroachment of brackish water from the sea), all alter sawgrass wetland ecosystems drastically, often leading to decreased prevalence of Cladium mariscus. These factors may impact African populations of the species.

Major references

• Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 960 pp.

• Clarke, C.B., 1901–1902. Cyperaceae. In: Thiselton-Dyer, W.T. (Editor). Flora of tropical Africa. Volume 8. Lovell Reeve & Co., London, United Kingdom. pp. 266–524.

• Hoenselaar, K., Verdcourt, B. & Beentje, H., 2010. Cyperaceae. In: Beentje, H.J. (Editor). Flora of Tropical East Africa. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 466 pp.

• Hooper, S.S. & Napper, D.M., 1972. Cyperaceae. In: Hepper, F.N. (Editor). Flora of West Tropical Africa. Volume 3. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 278–348.

• Kern, J.H., 1974. Cyperaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Series 1, Vol. 7(3). Noordhoff International Publishing, Leiden, the Netherlands. pp. 435–753.

• Simpson, D.A. & Inglis, C.A., 2001. Cyperaceae of economic, ethnobotanical and horticultural importance: a checklist. Kew Bulletin 56(2): 257–360.

• Tucker, G.C., 2003. Cladium. [Internet] In: Ball, P.W., Reznicek, A.A. & Murray, D.F. (Editors). Flora of North America Vol. 23. pp. 240–242. http://www.efloras.org/ florataxon.aspx?flora_id=1&taxon_id=107172. February 2011.

• Uchytil, R.J., 1992. Cladium jamaicense. [Internet] In: Fire Effects Information System, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, Montana, United States. http://www.fs.fed.us/ database/feis/plants/graminoid/clajam/ all.html. August 2009.

• Vanden Berghen, C., 1988. Flore illustrée du Sénégal. Monocotylédones et Ptéridophytes. Volume 9. Monocotylédones: Agavacées à Orchidacées. Gouvernement du Sénégal, Ministère du Développement Rural et de l’Hydraulique, Direction des Eaux et Forêts, Dakar, Senegal. 522 pp.

Other references

• Bryson, C.T. & Carter, R., 2005. Weedy sedges (Cyperaceae) of the world. [Internet] Poster for Weed Science Society of America. http://www.ars.usda.gov/ SP2UserFiles/Place/64022000/Posters/2005/ 2005_WSSA_CTB.pdf. August 2009.

• Burkill, H.M., 2000. The useful plants of West Tropical Africa. 2nd Edition. Volume 5, Families S–Z, Addenda. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 686 pp.

• Conway, V.M., 1936. Studies in the autecology of Cladium mariscus R.Br. 1. Structure and development. New Phytologist 35(3): 177–204.

• Conway, V.M., 1938. Studies in the autecology of Cladium mariscus R.Br. 4. Growth rates of the leaves. New Phytologist 37(3): 254–278.

• Gordon-Gray, K.D., Baijnath, H., Ward, C.J. & Wragg, P.D., 2009. Studies in Cyperaceae in southern Africa 42: pseudo-vivipary in South African Cyperaceae. South African Journal of Botany 75(1): 165–171.

• Hsieh, Y.P. & Weber, O.J., 1984. Net aerial primary production and dynamics of soil organic matter formation in a tidal marsh ecosystem. Soil Science Society of America Journal 48: 65–72.

• Ivey, C.T. & Richards, J.H., 2001. Genotypic diversity and clonal structure of Everglades sawgrass, Cladium jamaicense (Cyperaceae). International Journal of Plant Sciences 162(6): 1327–1335.

• Kaggwa, R.C., Mulalelo, C.I., Denny, P. & Okurut, T.O., 2001. The impact of alum discharges on a natural tropical wetland in Uganda. Water Research 35(3): 795–807.

• Lorenzen, B., Brix, H., McKee, K.L., Mendelssohn, I.A. & Miao, S., 2000. Seed germination of two Everglades species, Cladium jamaicense and Typha domingensis. Aquatic Botany 66(3): 169–180.

• Mason, O.T., 1988. American Indian basketry. Dover Publications, Mineola, New York, United States. 529 pp.

• Miao, S.L., Kong, L., Lorenzen, B. & Johnson, R.R., 1998. Versatile modes of propagation in Cladium jamaicense in the Florida Everglades. Annals of Botany 82: 285–290.

• Moerman, D.E., 1998. Native American ethnobotany. Timber Press, Portland, Oregon, United States. 933 pp.

• Ponzio, K.J., Miller, S.J. & Lee, M.A., 1995. Germination of sawgrass, Cladium jamaicense Crantz, under varying hydrologic conditions. Aquatic Botany 51(1–2): 115–120.

• Roberts, N., 1988. Dambos in development: management of a fragile ecological resource. Journal of Biogeography 15: 141–148.

• Rowell, T.A., 1986. Sedge (Cladium mariscus) in Cambridgeshire: its use and production since the seventeenth century. The Agricultural History Review 34(2): 140–148.

• Royal Botanic Gardens Kew, 2008. Cladium mariscus. [Internet] Seed Information Database (SID). Version 7.1. http://data.kew.org/ sid/SidServlet?Source=epic&ID=5908&Num=WP5. March 2010.

• USDA, NRCS, 2009. Cladium mariscus ssp. jamaicense. [Internet] In: The PLANTS Database, National Plant Data Center, Baton Rouge, Louisiana, United States. http://plants.usda.gov/ java/profile?symbol=CLMAJ. August 2009.

Sources of illustration

• Kern, J.H., 1974. Cyperaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Series 1, Vol. 7(3). Noordhoff International Publishing, Leiden, the Netherlands. pp. 435–753.

Author(s)

• G. Vaughan, Museo Arqueológico de Tunja, UPTC, Avenida Central del Norte, Tunja, Boyacá, Colombia

Correct citation of this article

Vaughan, G., 2011. Cladium mariscus (L.) Pohl. [Internet] Record from PROTA4U. Brink, M. & Achigan-Dako, E.G. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.

Accessed 31 March 2025.

• See the Prota4U database.