 |
|
|
||||
| NAS - Nonindigenous Aquatic Species |
Translate this page with 
Common Name: Crack willow
Taxonomy: available through 
Identification: Tree to 20 m (65 ft) tall. Bark dark brown or dark gray, deeply divided into scaly forking ridges. Twigs olive to yellowish-brown, brittle. Branchlets spreading, green to reddish, hairy when young but becoming glabrous. Leaves alternate, long, lanceolate or linear-lanceolate, 7-13 cm (2.8-5 in) long and 1.5-3 cm (0.6-1.2 in) wide, coarsely serrate, shiny yellowish-green above, pale to white-glaucous below. Flowers in catkins 3-6 cm (1.2-2.4 in) long at ends of short leafy branchlets, very small, numerous, with yellowish hairy scales, pistillate and staminate on different trees, appearing in early spring with the leaves. Fruits numerous conical capsules about 5 mm (0.2 in) long, opening in late Spring to release many very small cottony-tufted seeds.
Size: to 20m (65 feet)
Native Range:
Eurasia
| ||
 Alaska |
Hawaii |
Caribbean |
Interactive maps: Continental US, Alaska, Hawaii, Caribbean
Nonindigenous Occurrences: widespread
in USA (CO,
CT,
DC,
DE, IA,
ID,
IL,
IN,
KS, KY,
MA,
MD, ME,
MI,
MN,
MO,
MT,
ND, NE,
NH,
NJ,
NM,
NY,
OH,
PA,
RI,
SD,
UT,
VA,
VT,
WA,
WI,
WV,
WY).
widespread in the Great Lakes by 1886
Ecology: Usually found in wet soil near streams and lakes. The name derives from the twigs which break off very easily and cleanly at the base with an audible crack. The broken twigs and branches take root readily, enabling the species to colonize new areas, where the broken twigs fall into rivers and can be carried some distance downstream. It is particularly adept at colonizing new riverside sandbanks formed after floods.
Means of Introduction: deliberate release
Status: established
Impact of Introduction: can form dense thickets several metres thick, with densely spaced stems (FEIS, 2000) that could be major impediments to access waterways. S. fragilis is a thicket-forming species (Cremer, 1995). S. fragilis also have extensive roots, which can grow out into the stream, “trapping silt and layering new roots over the top of the old ones…creating a broad shallow stream” (Muyt, 2001) and “block streams, drains and culverts (Webb, Sykes & Garnock-Jones, 1988). They are a major impediment to access waterways. As semi-aquatic species, confined to stream banks or beds or moist locations, willows are unlikely to grow near enough to cause structural or visual damage to cultural sites.
Remarks: It readily forms natural hybrids with White Willow Salix alba, the hybrid being named Salix × rubens Schrank.
References
Oklahoma Biological Survey. 2008. Salix fragilis. http://www.biosurvey.ou.edu/shrub/safr.htm
Wikipedia.
Salix fragilis. Retrieved on 2008-10-26. http://en.wikipedia.org/wiki/Salix_fragilis
Other Resources:
USDA/NRCS PLANTS Database
http://www.nre.vic.gov.au/DPI/Vro/vrosite.nsf/0d08cd6930912d1e4a2567d2002579cb/1fe6ed01247d8c49ca2574c8002cccc6/$FILE/impact%20crack%20willow.pdf
Author: Ling Cao
Contributing Agencies: 
NOAA - GLERL
Revision Date: 11/5/2008 Citation for this information:
Ling Cao. 2009. Salix fragilis. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=2684> Revision Date: 11/5/2008
| AccessibilityFOIAPrivacyPolicies and Notices | |
  |
|