There are actually many flowers that symbolize friendship. The color yellow is often used as a symbol of friendship when giving flowers, regardless of the type of flower given. Possibly the most popular option for a flower to show friendship is the yellow rose.
However, there are other types of flowers that can be given to signify different meanings of friendship. An example of this would be the iris symbolizing a friendship that is cherished. Giving someone a daisy could denote loyalty to that person. Other flowers given to show friendship include the hydrangea, freesia, red carnations and the chrysanthemum.