TWO PLANTS.  Litchi tomatoes are neither litchi or tomatoes, although the plants look somewhat like very scary tomato plants.  Covered in thorns, even on the leaves and husks, care is required when picking the fruit.  When fully ripe, the sweet red fruit tastes a bit like tart cherries mixed with strawberries.  Fun and scary to grow at the same time.  AT LEAST TWO PLANTS ARE REQUIRED FOR FRUIT SET.