On any lot on which a front yard is required by this ordinance no wall, fence or other structure shall be erected and no hedge, tree, shrub or other growth or structure of any kind shall be maintained in such location within such required front yard so as to obstruct view.

Any fence, wall, hedge, or shrubbery higher than a base line extending from a point two and one-half (2½) feet above walk grade to a point four and one-half (4½) feet above walk grade at the depth of front yard required is hereby declared to be an obstruction to view, except single trees, having single trunks which are pruned to a height of seven (7) feet above walk grade.