In English folklore, a willow tree is believed to be sinister as it was said that willow trees could uproot themselves and stalk travellers. Willow trees are also seen as symbols of love and happiness as well as known for grief.
In biblical times, willow trees were actually seen as trees of celebration but that changed over time which has lead to it being associated with sadness and mourning. This can be seen in classic poems and classic art like Ophelia drowning herself near a willow tree. The willow tree has a bitter taste and it is said that this is what gave it is new association. In some areas of the world the Willow tree branches are used on Palm Sunday instead of Palm branches.
Willow tree was also used in the Disney film Pocahontas as a way Pocahontas connected to nature.