The Giant Reed is probably native to Asia and was introduced to the Mediterranean basin in ancient times. It has always been used for the construction of huts and the making of arrows, fishing rods, musical instruments, and plant supports. Pliny the Elder described the plant and its uses, testifying to a cultivation that dates back millennia.
It is a perennial herbaceous species that can grow up to 3 m tall. The stems (called 'culms') are woody, cylindrical, and hollow inside with a diameter of 1-4 cm; they appear erect and stiff. They have noticeable nodes and their color ranges from green to brown depending on age.
The leaves are alternate, arranged 180° apart from each other, and wrap around the culm to form a protective sheath. They are pale green or glaucous in color and have a thick, leathery blade with visible veins. Their shape is lanceolate and they have a finely toothed margin; they can grow up to 60 cm long. The leaves turn yellow during winter or periods of drought.
Flowering occurs between July and September. The flowers are gathered in a panicle inflorescence (30-60 cm long) that develops at the apex of the stem. It appears as a fluffy and dense structure, first violet in color and then white-golden. Pollination is anemophilous, that is, by the wind.
The fruit is a caryopsis, dry and indehiscent, typical of grasses. The seeds are not fertile, so agamic propagation is the only way to spread the species.
The rhizomes are the underground part of the plant; they carry numerous roots and form an intricate tangle that can penetrate the soil up to 1 m deep. The horizontal growth of the rhizomes determines the expansion of the plant on even very large surfaces. Even fragments of rhizome or stem can emit adventitious organs that come into contact with the soil, giving rise to new plants.
The Giant Reed is a heliophile and hygrophyl species; it grows on moist soils and adapts to live even on flooded soils (such as in swamps and marshes). It is often found at the edges of fields, along ditches and drainage channels, as well as on road edges. It is a very competitive species and under optimal conditions can create dense monospecific populations.
Maintenance and cleaning activities of canals and rivers can contribute to the spread of the species as they generate a large amount of fragments that can give rise to new plants.
Due to its ability to produce a high amount of biomass, the Giant Reed is becoming an important source of renewable energy.