BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Arundo donax | Giant Reed 



GENERAL BOTANICAL CHARACTERISTICS : 
Giant reed is an introduced, perennial grass that grows in clumps to
heights of 6 to 18 feet (3-6 m) [3,6].  In warm climates its panicles
can grow 7.9 to 15.7 inches (20-40 cm) long.  Its leaves are 2 to 2.5
inches (5-6 cm) wide.  The roots are extensive and densely matted [10].
Plants can form dense floating mats in streams and rivers [14].  Giant
reed is very similar to common reed (Phragmites australis) but has hairy
lemmas and smooth rachillas while common reed has smooth lemmas and
hairy rachillas [5].


RAUNKIAER LIFE FORM : 
   Phanerophyte
   Geophyte
   Hydrophyte


REGENERATION PROCESSES : 
Giant reed is propagated mainly by rhizomes or culm cuttings [3].  Stem
segments can slough off and reestablish themselves where they fall [17].
Giant reed may only flower at "several year intervals" [17].  Its seeds
are dispersed by birds, wind, and water [17].


SITE CHARACTERISTICS : 
Giant reed is predominantly a riparian species that aggressively
colonizes riverbanks, marshes, and floodplains in the southern United
States [2,5,14].  It grows in warm, sunny areas below 5,000 feet (1,524
m) on either steep or flat ground [10].  Much of the soils in these
areas are derived from limestone parent material [2].  Giant reed
density increases as it nears the water's edge [17].

Some plant associates of giant reed include willow (Salix spp.),
mesquite (Prosopis spp.), tree tobacco (Nicotiana glauca), pecan (Carya
spp.), California sycamore (Plantanus racemosa), saltcedar (Tamarix
gallica), mulberry (Morus spp.), common reed, burmudagrass (Cynodon
dactylon), seepwillow (Baccharis salicifolia), spiney aster (Aster
spinosus), horsetail rush (Equisetum spp.), and burrobrush (Hymenoclea
spp.) [2,14].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Giant reed can become the climax species in some riparian areas by
preventing the establishment and growth of native riparian communities
[17].  In many parts of the Southwest, giant reed is replacing the
native common reed [5].
  


SEASONAL DEVELOPMENT : 
Giant reed is a rapidly growing species that may only flower once every
"several years" between September and October [6,17].  Growth rates in
California have been reported as follows [17]:

Established Colony*                     Original Stand

time              avg max. stem ht.      time         avg max. stem ht.

40 days after cut    8.2 ft (2.5 m)        4 years        12.5 ft (3.8 m)  
150 days after cut  13.2 ft (4.0 m)       35 years        19.4 ft (5.9 m)

*Established colonies are those with previously established rhizomes.

Growth rates of established rhizomes averaged 2.46 inches (6.25 cm) per
day after 40 days growth and 1.05 inches (2.67 cm) per day after 150
days growth [17].

Related categories for Species: Arundo donax | Giant Reed