The four trees above* all grow in San Diego, where a famous children's author lived. (UC San Diego named their main library after him.)
Take the shape of the first tree, give it some bright colors like the other three, and you can see how that author was inspired to create what FICTIONAL tree species?
Congratulations to solvers Lucia, Spencer, Anna K., Carl, Ena, Summer, Zachary Z., Maddy, Yapa, Hazel, Charlie, Atticus, Avery, Alex M., Narayan, Dhruv, Nicholas, an unspecified Peter, Josh Moore, Parley, and teacher Zachary!