Flowers That Grow on Cactus

Flowers of Desert Cacti

• The flowers of the cacti that thrive in dry desert climates are usually delicately shaped even though they can be large. When grown as houseplants, these cacti will generally only flower profusely when kept at cooler temperatures -- between 20 and 30 degrees cooler -- in the winter than in the summer. This temperature difference stimulates the flowering process. Some, like the barrel cactus, only bear their flowers once they have fully matured. Others flower even when they are young plants, such as the chin cacti. While the flowers of the desert cacti come in a variety of shapes from bell-shaped to flat and colors from red and purple to white, they typically have dozens of individuals petals that are clustered together in a tight group to give the flowers their delicate appearance.

Flowers of Tropical Cacti

• Tropical cacti typically have smooth skin and no spines, but many varieties also sport colorful flowers. The flowers of these plants -- which include the Christmas and Easter cactus -- can be encouraged to form by changing the amount of light the plant receives, the temperatures it is exposed to and the water it is given. Flowers will often form in the joints between the pieces of succulent stems, and many do not flower until they are several years old. The orchid cacti are another family of tropical cactus plants, with colorful flowers that bloom only at night.

Growth of the Flowers

• Whether desert or tropical cactus, each member of the cactus family has a unique flower structure that is not found in any other type of plant. This structure, called the areole, is different on almost every species of cactus and can be used to tell the difference between closely related types. The areole consists of spines that are of a size and shape particular to the type of cactus, where the flowers will form once the process begins. These structures can form along the flat edges of the cactus or on the tips; this also depends on the type of cactus, and is a means for identification. Another thing cacti flowers have in common is that the reproductive system of the flower itself works differently; in many cases, the inside of the flower ends up being hollow because of the incomplete formation.

Conditions for Flowering

• Cacti can be difficult to get to bloom when kept as houseplants because some rely on very specific circumstances in order to tell them when to flower. Tropical cacti require a resting period in order to bloom, and a change in temperature that cues the plant into making flowers. In some cases, both tropical and desert cacti can drop their flowers before they even open if the humidity is too high or low. Similarly, both types can fail to flower during their typical blooming period if kept in conditions incorrect for their species during the other times of the year.