Cacti are fleshy, succulent plants that mostly come from the American continent. They store water in their stems that they use sparingly, and therefore, rarely need watering. They acquire water from their extensive, fibrous root systems that draw moisture from the soil through exceptional suction pressure. Cacti are flowering plants that differ greatly in shape and size. Spines, which are cacti's most notable feature, also vary greatly, with some species have long, brightly colored spines and others having short, sparse spines.

Cacti grow in a wide range of shapes and sizes with different flowering and spine types.

Rainforest Cacti

While the majority of cactus species are found in the hot, arid desert, a few species exist in rainforests. Orchid cacti have flat stems that resemble leaves and big bright flowers that vary in color. Holiday cacti bloom small flowers from long branching stems at Easter, Thanksgiving and Christmas. Rainforest cacti prefer cooler, shadier, wetter conditions than desert cacti.

Prickly Pear Cacti

Prickly pear cacti encompasses the largest genus with over 300 species growing in a wide range of regions from Canada to Argentina. They have flat, paddle-like stems with spines that can be short or long. Prickly pear cacti flower in a variety of colors that are large and wide and bear edible fruits. Light, nutrient-rich soil keeps prickly pear cacti happy, as well as a bright, warm area.

Columnar Cacti

Columnar cacti have tall, narrow, cylindrical-shaped stems with vertical ribs. Spike density, size and flowering varies with each species. As with other arid cacti, columnar cacti prefer dry, warm, bright conditions and little moisture.

Barrel Cacti

Barrel cacti are cylindrical, resembling the shape of barrels native to the American Southwest and high limestone altitudes of Mexico. They have strong, colorful, showy spines and flowers, and can grow up to 10 feet tall. They prefer loamy, slightly acidic soil and a warm sunny location. Barrel cacti also grow very slow and don't need much fertilizing.

Hedgehog Cacti

Hedgehog cacti get their name from their globular shapes that are densely covered in spines that make them resemble hedgehogs. Native to Mexico and the southwestern U.S., they have cup-shaped flowers that, unlike other cacti, don't close up at night. Hedgehog cacti like sunny, warm areas and are sensitive to moisture and should only be watered from the bottom.

Pincushion Cacti

The majority of pincushion cacti are found in Mexico, but also grow in other parts of Central America and areas of the U.S. This small, ball-like cactus puts on a magnificent display of star-shaped flowers and has a thick coat of spines. Pincushion cacti are tolerant of a variety of different soils and prefer dry conditions.