In large bowl, combine sugar, 1 cup margarine and cream cheese; beat until light and fluffy. Add orange peel, orange juice, 1 teaspoon vanilla and egg; blend well. Add flour, baking soda, cream of tartar and 1/2 teaspoon salt. Cover with plastic wrap; refrigerate 2 hours or until firm.
Heat oven to 375°F. Using stockinette-covered rolling pin and floured pastry cloth, roll out 1/4 of dough at a time to 1/8-inch thickness. (Keep remaining dough refrigerated.) Cut with floured leaf-shaped cookie cutter. Place 1 inch apart on ungreased cookie sheets.
Bake at 375°F. for 4 to 6 minutes or until edges are light golden brown. Immediately remove from cookie sheets; cool 15 minutes or until completely cooled.
In large bowl, combine butter and shortening; beat until light and fluffy. Add 1 teaspoon vanilla and 1/8 teaspoon salt. Beat in powdered sugar 1 cup at a time, scraping down sides of bowl. Add 2 tablespoons milk; beat at high speed until light and fluffy. Add enough additional milk for desired spreading consistency.
Divide frosting into 2 small bowls. To one bowl of frosting, add melted chocolate; beat until well blended. To other bowl of frosting, add red and yellow food color; blend well. Spread cooled cookies with 1 of the frostings; pipe veins on leaves with other frosting. Let stand until set.