WILLOW, COTTONWOOD, AND 

 RUSSIAN-OLIVE 



S3I1X spp., PopuJus spp., Elaeagnus augustifolia h. 



Willow, Cottonwood, and russian olives will grow prolifically near 

 most any body of freshwater and can particularly become pests along 

 irrigation or drainage ditches. These woody plants consume large 

 quantities of water, can degrade the canal lining, disrupt the water 

 flow, trap sediment, and can become obstacles in the regular 

 maintenance of irrigation systems. 



There are numerous species of willows ( Sali}^, all of which can be 

 troublesome. Generally, the simple, alternate leaves are long and fairly 

 narrow, widening slightly at the middle (insert 3). Most species have 

 finely serrated leaf margins and some hair. The flowers are in catkins, 

 but these can vary greatly according to the species. The willows 

 produce numerous, small seeds each with a tuft of hair at their base. 



Cottonwoods {Populu^ are fast-growing deciduous trees which 

 include a number of different species. Commonly they all have 

 furrowed bark, stout branches, drooping catkins appearing before the 

 leaves, numerous small seeds with tufts of hair, and simple leaves which 

 grow alternately along the stems. The leaves vary from spear-shaped 

 to egg- or triangular shaped (insert 2), but generally, the lower surfaces 

 are paler in color than the upper. Cottonwood leaf margins are smooth 

 to serrated, but somewhat serrated in most species. 



Russian-olive ( Elaeagnus augustifolid) is a deciduous shrub or small 

 tree which is usually cultivated but sometimes escapes and becomes 

 a pest. The leaves are roughly spear-shaped, approximately 35 to 75 

 millimeters long, and olive-green in color (insert 1). Branches are 

 reddish-brown when young and often have thorns, but as the older 

 stems mature they become dark brown and very rough. The 

 silvery-yellow fruits resemble small commercial olives, but are covered 

 by tiny, silvery scales. These scales also cover the flowers, and 

 undersides of the leaves and branches. 



76 



