The huge tree here is a Hybrid Crack Willow (Salix X rubens).  It is not a native plant, but a hybrid of two European species that has become widely established in North America.  Crack Willows are so named because the twigs and branches bend easily and then break with a snap or crack.  You will often see Crack Willow trees with branches that have grown heavy, bent outwards and then split away from the trunk.  Crack Willows are very common along stream banks. They are spread when broken twigs fall in the water and are deposited in a new location where they are able to take root like a natural cutting.  Willows can grow very fast and this giant may not be quite as old as its size and gnarled form might lead you to believe. 

Willows have many uses.  The straight young branches that grow rapidly from a cut stump are supple enough that they can be used in weaving.  In Europe riverside willows were pruned and maintained specifically to provide a regular crop of branches, a process known as pollarding. You can see the distinctive shape of the pollarded willows in old painting and photographs.  Many woven items from baskets and fish traps to walls and fences can be made from willow twigs.  The inner bark of willow contains an effective pain killer, and has been used for thousands of years to treat pain and reduce inflammation.  The active ingredient, salicin, gave rise to the world’s first synthetic drug acetylsalicylic acid (ASA).  Millions of doses are still sold every year under brand names like Aspirin.