Hyacinth Smith is an observant girl who is able to see things that regular people cannot. She is a peacemaker, for she dislikes conflict and does not like to offend others, but she grows to have an inner strength and a joy built out of sorrow. She also has a way with trees, able to ask them to do unusual things. She planted trees for each of her children, and each tree dies or flourishes in unison with the child.
According to her son, Henry, Hyacinth has black hair and "very gray eyes".