  The rank of a graph is defined to be the rank of its adjacency matrix. A
graph is called reduced if it has no isolated vertices and no two vertices with
the same set of neighbors. A reduced graph $G$ is said to be maximal if any
reduced graph containing $G$ as a proper induced subgraph has a higher rank.
The main intent of this paper is to present some results on maximal graphs.
First, we introduce a characterization of maximal trees (a reduced tree is a
maximal tree if it is not a proper subtree of a reduced tree with the same
rank). Next, we give a near-complete characterization of maximal `generalized
friendship graphs.' Finally, we present an enumeration of all maximal graphs
with ranks $8$ and $9$. The ranks up to $7$ were already done by Lepovi\'c
(1990), Ellingham (1993), and Lazi\'c (2010).
