Arundo donax, the giant reed, is a tall perennial reed or cane species. Other vernacular names include giant cane, Spanish cane, wild cane, and in Spanish, . The scientific name Arundo and donax are respectively the old Latin and Greek names for reed.Gledhill D. 1985. The Names of Plants. Cambridge University Press.
Arundo donax grows in damp soils, either fresh or moderately saline, and is native to the eastern Mediterranean region and across southern Asia to Japan.CABI, 2020. Arundo donax (giant reed). In: Invasive Species Compendium. Wallingford, UK: CAB International. https://www.cabi.org/isc/datasheet/1940Global Invasive Species Database (2020) Species profile: Arundo donax. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=112 on 12-01-2020. It has been widely planted and naturalised in the mild temperate, subtropical and tropical regions of both hemispheres, especially in the Mediterranean, California, the western Pacific and the Caribbean and is considered invasive in North America and Oceania.Perdue, R.E. Arundo donax—Source of musical reeds and industrial cellulose. Econ Bot 12, 368–404 (1958). https://doi.org/10.1007/BF02860024Lambert, A.M., Dudley, T.L. and Saltonstall, K., 2010. Ecology and impacts of the large-statured invasive grasses Arundo donax and Phragmites australis in North America. Invasive Plant Science and Management 3(4): 489–494. It forms dense stands on disturbed sites, sand dunes, in wetlands and riparian habitats.
Description Arundo donax generally grows to in height (in ideal conditions can exceed ). The hollow stems are in diameter, either unbranched or with small bamboo-like side shoots. The grey-green swordlike leaves are alternate, long and wide with a tapered tip, and have a hairy tuft at the base. Overall, the plant resembles an outsize common reed (Phragmites australis) or a bamboo (Poaceae subfamily Bambusoideae).
It flowers in late summer, bearing upright, white feathery plumes long, that are usually seedless or with seeds that are rarely fertile.(Johnson et al. 2006) Instead, it mostly reproduces vegetatively by tough, fibrous underground rhizomes that form knotty, spreading mats which penetrate deep into the soil, up to deep. Stem and rhizome pieces less than long and containing a single node could sprout readily under a variety of conditions. This vegetative propagation appears well adapted to floods, which may break up individual A. donax clumps, spreading the pieces, which may sprout and colonise downstream.
Biology Arundo donax is a tall, perennial grass in the subfamily Arundinoideae, characterised by C3 photosynthesis. The stems produced during the first growing season are unbranched and photosynthetic. In the Mediterranean, where a temperate climate is characterised by warm and dry summer and mild winter, new shoots of giant reed emerge around March, growing rapidly in June and July and producing stems and leaves. From late July the lower leaves start to dry, depending on seasonal temperature patterns. Drying accelerates during autumn when anthesis occurs from the beginning of October to the end of November. In this phenological stage moisture content falls significantly. In the low temperatures of winter giant reed stops its growth; regrowth occurs in springtime. Giant reed behaves as an annual in Central Europe where soil temperatures are low, due to poor freeze tolerance of the rhizomes.
The minimum growth temperature reported for giant reed is ,Spencer, D.F., Ksander, G.G., 2006. Estimate Arundo donax ramet recruitment using degree-day based equation. Aquat. Bot. 85, 282–288. with a maximum temperature of . It has a high photosynthetic capacity, associated with absence of light saturation. Carbon dioxide exchange rates are high compared to other and species; maximum CO2 uptake ranged from 19.8 to 36.7 μmol/s·m2 under natural conditions, depending on irradiance and leaf age. Carbon dioxide exchange is regulated by leaf conductance.Rossa B, TuAers AV, Naidoo G, von Willert DJ. 1998. Arundo donax L. (Poaceae)—a C3 species with unusually high photosynthetic capacity. Botanica Acta. 111:216–21.
Studies have found this plant to be rich in active tryptamine compounds, but there are more indications of the plants in India having these compounds than in the United States.Erowid Arundo donax Info Page 1 Toxins such as bufotenidineErowid Arundo donax Info Page 3 and gramine have also been found.
The dried rhizome with the stem removed has been found to contain 0.0057% DMT, 0.026% bufotenine, 0.0023% 5-MeO-MMT. The flowers are also known to have DMT and the 5-methoxylated N-demethylated analogue, also 5-MeO-NMT. The quite toxic quaternary methylated salt of DMT, bufotenidine, has been found in the flowers, and the cyclic dehydrobufotenidine has been found in the roots. A. donax is also known to release volatile organic compounds (VOCs), mainly isoprene.Owen, S.M., Boissard, C., and Hewitt, C. N. Atmospheric Environment, 35, 2001, pp 5393–5409
Genetic background In some areas where giant reed grows (including the Mediterranean area and the United States), viable seeds are not produced.Saltonstall, K., Lambert, A., Meyerson, L.A., 2010. Genetics and reproduction of common (Phragmites australis) and giant reed (Arundo donax). Invasive Plant Sci. Manag. 3, 495-505. It is reported that sterility of giant reed results from failure of the megaspore mother cell to divide.Bhanwra R.K., Choda S.P., Kumar S. 1982. Comparative embryology of some grasses. Proceedings of the Indian National Science Academy, 48, 152–162. This sterility, which drastically limits genetic variability, is an obstacle for breeding programs which aim to increase the productivity and biomass quality for energy conversion.Mariani C., R. Cabrini, A. Danin, P. Piffanelli, A. Fricano, S. Gomarasca, M. Dicandilo, F. Grassi and C. Soave. 2010 Origin, diffusion and reproduction of the giant reed (Arundo donax L.) a promising weedy energy crop. Annals of Applied Biology. 157: 191–202. A total of 185 clones of A. donax were collected from California to South Carolina and genetically fingerprinted with the SRAP and TE-based markers.Ahmad R., Liow P.S., Spencer D.F., Jasieniuk M. 2008. Molecular evidence for a single genetic clone of invasive Arundo donax in the United States. Aquatic Botany. 88: 113–120. Giant reed exhibited no molecular genetic variation despite the wide genomic coverage of the markers used in this study. The molecular data strongly point to a single genetic clone of A. donax in the United States, although multiple introductions of this plant into the United States have been documented. Another study conducted in the Mediterranean area sampled giant reed from 80 different sites, and demonstrated low gene diversity in this region as well. Results indicate the occurrence of post-meiotic alterations in the ovule and pollen developmental pathway. AFLP data support a monophyletic origin of giant reed and suggest that it originated in Asia, spreading from there into the Mediterranean Basin.
Ecology Giant reed is adapted to a wide variety of ecological conditions, but is generally associated with riparian and wetland systems. It is distributed across the southern United States from Maryland to California. Plants can grow in a variety of soils, from heavy clays to loose sands and gravelly soils, but prefer wet drained soils, where they produce dense monotypic stands.
Invasiveness and management Arundo is a highly invasive plant in southwestern North American rivers, and its promotion as a biofuel in other regions is of great concern to environmental scientists and land managers.Lambert, A.M., Dudley, T.L., Saltonstall, K., 2010. Ecology and impacts of the large-statured invasive grasses Arundo donax and Phragmites australis in North America. Invasive Plant Sci. Manag. 3, 489-494. Arundo donax was introduced from the Mediterranean to California in the 1820s for roofing material and erosion control in drainage canals in the Los Angeles area. Through spread and subsequent plantings as an ornamental plant, and for use as reeds in woodwind instruments, it has become naturalised throughout warm coastal freshwaters of North America, and its range continues to spread.
It has also been planted widely through South America and Australasia and in New Zealand it is listed under the National Pest Plant Accord as an "unwanted organism". Despite its invasive characteristics in regions around the world where it is not native, Arundo is being promoted by the energy industry as a bio-fuel crop. Some of the regions, such as the southeastern United States have natural disturbances, such as hurricanes and floods, that could widely disperse this plant.
It is among the fastest-growing terrestrial plants in the world (nearly per day). To present knowledge, Arundo does not provide any food sources or nesting habitats for wildlife. Replacement of native plant communities by Arundo results in low-quality habitat and altered ecosystem functioning. For example, it damages California's riparian ecosystems by outcompeting native species, such as willows, for water. A. donax stems and leaves contain a variety of harmful chemicals, including silica and various alkaloids, which protect it from most insect herbivores and deter wildlife from feeding on it. Grazing animals such as cattle, sheep, and goats may have some effect on it, but are unlikely to be useful in keeping it under control.
Arundo donax appears to be highly adapted to fires. It is highly flammable throughout the year, and during the drier months of the year (July to October), it can increase the probability, intensity, and spread of wildfires through the riparian environment, changing the communities from flood-defined to fire-defined communities.Coffman, G., Ambrose, R., Rundel, P., 2010. Wildfire promotes dominance of invasive giant reed (Arundo donax) in riparian ecosystems. Biol. Invasions 12, 2723-2734. After fires, A. donax rhizomes can resprout quickly, outgrowing native plants, which can result in large stands of A. donax along riparian corridors. Fire events thus push the system further toward mono-specific stands of A. donax.
A waterside plant community dominated by A. donax may also have reduced canopy shading of the in-stream habitat, which may result in increased water temperatures. This may lead to decreased oxygen concentrations and lower diversity of aquatic animals.
As the impact of Arundo donax increased in the environment and native species various efforts have been taken to reduce its population. It has few natural enemies in its introduced range. Several Mediterranean insects have been imported into the United States as biological control agents. The Arundo wasp, Tetramesa romana, the Arundo scale insect, Rhizaspidiotus donacis, and the Arundo fly, Cryptonevra are known to have some effect in damaging the plant. Tetramesa romana and more recently Rhizaspidiotus donacisis were registered in the US as biological control agents.
Other remedies like using mechanical force have also been employed, since outside its native range Arundo donax does not reproduce by seeds, so removing its root structure can be effective at controlling it. Preventing it from getting sunlight will deplete the plant of its resources and eventually kill it. Systemic herbicides and glyphosate are also used as chemical remedies.
The US Department of Homeland Security considers this plant invasive and in 2007 began researching biological controls. In 2015, Texas Senator Carlos Uresti passed legislation to create a program to eradicate Arundo donax using herbicides and the Arundo wasp.
In New Zealand's northernmost region, Arundo donax crowds out native plants, reduces wildlife habitat, contributes to higher fire frequency and intensity, and modifies river hydrology.
Uses
Energy crop