Complex sentence: Sweet gum is one of the main forest trees valuable in south-eastern of United States and popular ornamental tree in temperate climates, it is recognizable by the combination of its five-pointed star-shaped leaves and its hard, spiked fruits.
Split into simpler sentences: Sweet gum is one of the main valuable forest trees in the southeastern United States, and is a popular ornamental tree in temperate climates. It is recognizable by the combination of its five-pointed star-shaped leaves and its hard, spiked fruits.