What Kind of Cactus Do I Have?
The habitats of cacti vary, and so do these plants. Here are general types of them:

Flowering
Not all cacti can bloom. Some can even produce fruit (like dragon fruit), but it’s rare indoors. They require a lot of sunlight and a cold, dry dormancy period in winter to blossom.

Cactus with long leaves
Most cacti don’t have leaves at all. Schlumbergera (Christmas cactus), Epiphyllum (orchid cactus), and some other epiphytic cacti have stem segments that look like long leaves.

Cactus with long spines
Many cacti have long spines, for example, Ferocactus or Echinocactus. Nonetheless, some grow long but soft spines like Tephrocactus aricalatus or Parodia leninghausii.
Columnar cacti, or ceroids, can be found in many genera. However, they are commonly found in the Cereus genus.

Moon cactus
Moon cactus is a Gymnocalycium mihanovichii that doesn’t have chlorophyll to photosynthesize. So, the only way to survive is by grafting on another cactus that provides them with nutrients. They come in many colors and varieties.

Prickly Pear
Bunny Ears, or Opuntia, is an extensive genus of cacti. If your plant has oval, round or flat elongated segments — it’s Opuntia. The most popular species are Indian fig opuntia and bunny ear cactus.