Most often, tropical plants are colorful with large leaves or flowers because of the excessive rainfall and sunshine in their tropical climates. Tropical plants do best in warm climates where there is no risk of cold temperatures, like Florida. In northern areas, you can grow tropical plants outdoors in summer and transport them indoors for winter. Keep some specific characteristics in mind when distinguishing tropical plants from other types of plants.
Smell the plants to see whether you can decipher a fragrance. Tropical plants often have a strong aroma, ranging from a sour rotting odor (literally a plant called carrion because it smells like roadkill) to an invigorating sweet smell.
Examine the green leaves on tropical plants, as they are usually greener than all other varieties. For example, the monstera deliciosa, or the Swiss cheese vine, grows very dark emerald green leaves and flourishes in shade, since sunlight directly on it will burn the leaves, creating holes like in Swiss cheese.
Observe the size of the leaves besides just the color. Tropical plants can have leaves that grow up to several feet long and wide, some of the larges leaves on any plant. For example, the macaranga grandifolia has leaves that grow up to 2 feet wide, and the canna leaves will grow long and narrow, but are still almost 2 feet wide as well.
Look for large flowers on the plant, since this is a common attribute for tropical plants. The flowers are also in bright shades, like red, orange, purple, blue, yellow, pink or cream. Consider the African tulip tree, that can grow up to four stories tall with cup-shaped flowers to collect rain and produce nectar for hummingbirds. The flowers are bright orange and red, and when they are heavy with nectar, the flowers turn yellow.
Take a picture of the tropical plant if you can't identify it, and visit a tropical gardener's website to research and identify if all else fails.