An intergeneric hybrid is a cross between plants in two different genera in the same family. They are closely related enough that pollination will produce a hybrid, though the seeds of this hybrid are usually sterile.
For example, the Leyland cypress (× Cupressocyparis leylandii) is a result of crossing a Monterey cypress (Cupressus macrocarpa) with a Nootka cypress (Chamaecyparis nootkatensis).
Propagation of the Leyland cypress is usually carried out through cuttings, though it is possible for this tree to produce seeds that will germinate. Asexual propagation, however, is preferable since it will ensure that the new plant has the same characteristics.