Cacti thrive in arid regions and deserts, making them well-adapted to harsh conditions. These plants belong to the group of succulents, known for their thick, fleshy tissues designed to store water.

While all cacti are succulents, not all succulents can be classified as cacti. What sets cacti apart is their areoles—small, cushion-like structures on their surface.

These areoles give rise to sharp, pointed spines, which are modified leaves. Most cacti lack traditional leaves, but they produce flowers and fruits, serving as vital resources for desert wildlife.

A Diverse Group

Cacti come in over a thousand species, showcasing incredible variety. Some species have a single, rounded form, while others display intricate branching structures. Sizes range from tiny plants comparable to grapes to towering giants taller than buildings.

Notable Types of Cacti in the United States

Saguaro Cactus

The saguaro is an iconic plant of the United States, reaching heights of 40-50 feet or more as it matures. This impressive cactus is native to the Sonoran Desert and plays a critical role in its ecosystem.

Its large trunk provides shelter to wildlife, and its nectar and fruits are key food sources for many species. The saguaro belongs to a single species, Carnegiea gigantea.

Pipe Cactus

A close relative of the saguaro, the pipe cactus (Stenocereus thurberi) grows tall and features multiple stems branching from a single base. This plant thrives in the heat of the Sonoran Desert and can be found in the Pipe Cactus National Monument in Arizona. Its sensitivity to freezing temperatures limits its range.

Prickly Pears

Prickly pears, from the genus Opuntia, are characterized by their branching, flattened pads that perform photosynthesis. These pads and their fruits are edible when properly prepared, offering nourishment to animals and people alike. Prickly pears are common in deserts and even grow in regions beyond these arid landscapes.

Chollas

Chollas, part of the genus Cylindropuntia, are close relatives of prickly pears. Unlike the flattened pads of prickly pears, chollas feature cylindrical stems. These cacti, such as the teddy-bear cholla, are covered in sharp spines and can vary widely in appearance.

Hedgehog Cacti

Belonging to the genus Echinocereus, hedgehog cacti form clusters and are typically small, growing under a foot in height. Their ribbed stems and rounded shapes make them visually distinct. These cacti are celebrated for their vibrant flowers and are found in arid regions of the southwestern United States and Mexico.

Barrel Cacti

Barrel cacti include species from the genera Ferocactus and Echinocactus. Their rounded shapes resemble barrels, with sizes ranging from under a foot to over 10 feet tall. These cacti are native to the southwestern United States and parts of Mexico.

Pincushion Cacti

Pincushion cacti, part of the genus Mammillaria, are small plants often just a few inches tall. They are characterized by hooked spines and compact forms. These cacti can be found in Central America, Mexico, and some regions of the southwestern United States.

Cacti are not only fascinating for their survival strategies but also essential to the ecosystems they inhabit, offering shelter, food, and beauty to the arid landscapes they call home.

How many kinds of cacti are there?

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