Brush both sides of leaves with oil. Arrange leaves, dull side up, around the sides of a greased and floured 10-inch tube pan; set aside.
Beat butter at medium speed with an electric mixer until creamy; gradually add sugar, beating well. Add eggs, 1 at a time, beating until blended after each.
Combine flour, salt, and baking soda; add to butter mixture alternately with sour cream, beginning and ending with flour mixture. Beat at low speed until blended after each addition. Stir in vanilla. Spoon batter into prepared pan.
Bake at 325° 1 hour and 20 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on wire rack 15 minutes. Remove from pan. Garnish, if desired.