Bake pie crust.
Add enough water to reserved syrup to measure 1 1/4 cups.
Heat to boiling in small saucepan.
Remove from heat; stir in gelatin until dissolved.
Stir in lemon peel and juice.
Refrigerate, stirring occasionally, until mixture mounds slightly when dropped from a spoon.
In chilled bowl, beat whipping cream until stiff.
Fold gelatin mixture and mandarin orange segments into whipped cream.
Pour into crust.
Refrigerate until set, about 2 hours.
Garnish with sweetened whipped cream and maraschino cherries if desired.