Grease (or spray) and flour 10-inch bundt or tube pan. Cream butter and sugar until fluffy. Add eggs 1 at a time beating well after each addition. Sift together dry ingredients. Add all at once to butter mixture. Blend just until smooth. Add sour cream, lemon rind, and poppy seeds. Blend just until smooth. Bake for approximately 1 hour. Let cool in pan before removing.