End-regular flower graphs <em>C<sub>r,s</sub></em>

In the present paper, we study the regularity of the endomorphism monoid of a class of graphs, which generalizes the cycle graph. We give a complete list of all end-regular r × s flower graphs. In particular, for an odd integer s ≥ 3, the s × s flower graph Cs,s has a regular endomorphism monoid, i.e., Cs,s is end-regular. For Cs,s, s ≥ 3 odd, we determine the cardinality and the rank of its endomorphism monoid (including a generating set of minimal size).