Types of Cacti: Varieties, ID, and Photos

Cacti come in various shapes and sizes, each with unique adaptations that help them thrive in their particular environment. For example, some cacti have thorns to protect them from predators, while others can bend a certain way that allows them to catch the sun’s rays.

There are many different types of cacti, from the small and spiny ball cactus to the towering Saguaro.

Cacti are most notable for their ability to survive in the harshest drought conditions in the world. Survive where no other plant can hope to. This capability makes them some of the hardiest plants on Earth and provides them with an identity that can’t be overlooked.

About Cacti:

All plants that belong to the Cactaceae family are called cacti (plural) or cactus (singular). There are about 127 genera that fall under the umbrella of the cactus family, with over 1700 cactus species combined.

Etymology

The word “cactus” is derived from the Greek word κάκτος (kaktos), which means “spiny plant.” This is in reference to the spines that are common among most cacti.

Taxonomy

The cactus family (Cactaceae) is one of the world’s most easily recognizable plant families. This is primarily due to their unique morphological features, including but not limited to: the lack of leaves, spines, and flowers that bloom only during the daytime.

The cactus family is a member of the order Caryophyllales, which also includes other succulent plants such as the aloe vera and the agave. The cactus family is further divided into four subfamilies: the Cactoideae, Opuntioideae, Maihuenioideae, and Pereskioideae.

• Cactoideae are typical cacti; green, globular, columnar, or tree-like with prominent spines, areolas, and tubercles. This subfamily contains the vast majority of plants in the cactus family.
• Opuntioideae contains about 15 genera, most of which are some variations of Prickly Pear Cacti. They are easily recognizable due to their characteristic flat, round pads. These pads are modified stems that serve several functions, such as photosynthesis, water storage, and fruit production. 
• Pereskioideae contains only three genera that don’t resemble any other cacti.
• Maihuenioideae contains only one genus, Maihuenia, with only two species. Both species are mat-forming cacti.

Distribution and Habitat:

Bar a single exception (Rhipsalis baccifera), every cactus species in the cactus family is found in the Americas.

Their habitats vary wildly, from rainforests to deserts. For example, the saguaro cactus (Carnegiea gigantea) is only found in the Sonoran Desert in the southwestern United States and northwestern Mexico. In contrast, the Christmas cactus (Schlumbergera ×buckleyi) is located in the Atlantic Forest biome of southeastern Brazil.

Besides their original habitat, various cacti have been naturalized in other regions with varying success. For example, plants from the genus Opuntia have been so naturalized as to become invasive in Australia. The Arabian Peninsula also has an invasive cacti problem thought to be perpetrated by specimens that escaped from cultivation.

Photosynthesis in Cacti

Instead of photosynthesizing during the day, they do so during the night. This is because the Transpiration portion of the process occurs during the night when there is less heat, and the sun isn’t present. Thereby preserving a vast amount of water that would have otherwise evaporated.

Many succulents have developed this method of photosynthesis, which is called “Crassulacean acid metabolism,” or CAM for short.

Cactus Identification

Many cactus plants adapted to survive in scorching conditions, making most cacti succulent. After all, they need some method to survive long periods without rainfall to survive in deserts.

In general, cacti are typically characterized by having a stem that is thickened, fleshy, and stores water. Some cacti have leaves that serve this function, but that’s an exception.

All cacti share a few core characteristics that help them to survive in their arid habitats. These include but are not limited to:

• Thickened photosynthetic stems (instead of leaves)
• Areoles ( small, raised cushion-like structures that bear spines/hairs)
• Spines ( modified leaves that help protect the plant from herbivores and conserve water loss)
• Absent or greatly reduced leaves

Stems:

As mentioned above, the stems of cacti are commonly used for photosynthesis. However, how a stem appears depends on the cactus type.

For instance, the Saguaro cactus has a long columnar stem that can grow up to 40 feet tall! Alternatively, the Prickly Pear Cactus (Opuntia) has flattened stems that look more like pads.

The stems of cacti are often green but can also be red, yellow, or purple. They usually have ridges (ribs) running along their length, which help to increase the space a cactus has for storing water. After heavy rainfall, as much as 90% of the stems might be full of water.

Leaves:

Most cacti don’t have leaves, at least not in the traditional sense. Flat, large leaves would cause the plant to lose too much water through transpiration. This is a significant issue if you’re a cactus that has to retain moisture in the harsh desert.

The only valuable aspect of a leaf, for a cactus anyway, is photosynthesis. But as mentioned above, cacti can easily photosynthesize using the stems, so what do they need leaves for?

Quite a bit; almost all cacti have leaves, just not in the traditional sense. The spines that emerge from the areolas are highly modified leaves. Since cacti don’t need their leaves for photosynthesis and having leaves with a large surface area would be an issue, cacti developed their leaves for another purpose entirely.

1. To ward off any would-be predators (herbivores).
2. To reduce the airflow around the cactus and reduce the rate of evaporation.
3. To provide some degree of shade to the plant.

It’s not nature’s way to waste resources, and anything that appears useless at first glance can be modified to serve a purpose; cactus leaves are no different.

The Prickly Pear Cactus (Opuntia) is an exception and has long-lasting leaves that sometimes carry out photosynthesis.

Note that some types of cacti have traditional leaves (wide and flat), but they don’t stay long, a few weeks to a couple of months at most. After that, the leaves are usually green and turn brown or red as they age. Once the leaves fall off, the plant may or may not begin to grow new ones.

Spines:

Cacti have areoles, which are small, raised portions of the stems the spines grow out of. As discussed before, spines are modified leaves in most cacti.

Cactus spines can be straight, curved, or barbed and come in various colors, including white, red, yellow, and black. The shape and color of the spines often give cacti their distinctive look.

Spines serve a major function in cactus identification; e.g., the Fishhook Barrel Cactus (Ferocactus wislizeni) can be immediately identified by its spines which are fishhook shaped.

They can be prickly and thorny, injuring predators and caretakers alike, or soft and smooth to the touch. The type of spine depends on the type of cactus, but almost all cactus plants have them in some form or another.

In a Prickly Pear Cactus, the spines don’t look like spines. Instead, they are like small tufts of wool that extend out of the areolas. These are called glochids, a particular type of spine.

Areolas:

An areola is a small, circular area where the spines and/or flowers of a cactus emerge from. In most cacti, the areolas are raised, giving the plant a more three-dimensional look. These serve the same function a node would in a non-succulent plant.

The size of an areola can be as small as 2 mm or as large as 10 cm. They are often covered in a fine down of hair or wool.

The number of spines that emerge from an areola can also be variable. It depends on how long an areola is designed to stay active. In most cacti, this window is relatively small, producing spines per areola that don’t surpass the single digits. While in other (e.g., Prickly Pear Cactus), areolas tend to stay active for much longer.

An areola is not just a place for spines and flowers to grow from; it’s also a place of great importance for the plant itself. This is because the areolas contain the axillary buds, which are responsible for the lateral growth of a cactus. In other words, the areolas allow the plant to branch out and grow sideways.

Flowers:

Cactus flowers are variable. But they do share some similarities even between genera. 

A common characteristic often seen in many cactus flowers is the flower tube. This is a relatively large tube (Pericarpel) that rises from an areola and continues to form a sizeable solitary flower.

These floral tubes can also develop areolas and spines, as if in continuation of the stem.

What Are Cacti Used For?

Ornamental Plants:

The first and most obvious use for cacti is as ornamental plants. Cacti come in all shapes and sizes, making them perfect for any home or garden. They are also low-maintenance, only needing water every couple of weeks (depending on the type of cactus).

Cacti can be used as standalone plants or potted with other succulents to create an arrangement. 

Smaller cacti usually lend themselves well to indoor cultivation, while taller columnar cacti are often used as garden features. The texture added by these types of cacti isn’t something other plants can replicate.

Most notably, Christmas Cactus plants remain hugely popular during the holidays. A Christmas without a Christmas Cactus feels incomplete. Its cousins, the Easter Cactus and the Thanksgiving Cactus, are also crucial commercial cactus plants.

Food:

Cactus fruits are often edible and sometimes quite tasty. The Prickly Pear Cactus (Opuntia) is a common source of cactus fruit. The fruits are called ‘tunas,’ and the pads are called ‘Nopales.’ Both are edible and a significant part of Indian cuisine.

Cactus fruits are often used in salads, salsas, jams, and jellies. You can even eat them raw as a snack.

The Indian Fig Opuntia (Opuntia ficus-indica) is a notable example of Prickly Pear Cacti being used for food. This plant is grown as a domesticated crop in that world region.

Cactus pads are commonly used in Mexican cuisine. They can be grilled, roasted, or stewed. In addition, they are often used as an ingredient in egg dishes such as scrambles and omelets.

The Peruvian Apple Cactus (Cereus repandus) is another cactus used as a food source. The fruits of this plant, called the Peruvian Apples, are often used in pies and jams.

Organic Dragon fruits and Saguaro fruits are other notable examples. However, do note that harvesting Saguaro is illegal in many parts of the US.

Fodder:

Cactus plants are sometimes used as fodder for livestock. This is most common in arid and semi-arid areas of the world, where other food sources are scarce.

The primary way to use these plants as fodder is to remove the spines first. This means this requires human intervention before any cactus is safe for consumption.

The local wildlife consumes the Saguaro Cactus fruits en masse. Gila woodpeckers and gilded flickers are only some birds that use these cacti as nests.

Psychoactive Drugs:

Certain cactus plants contain psychoactive alkaloids that can cause hallucinations. The San Pedro cactus (Echinopsis pachanoi) is the most well-known. This cactus is often used in shamanistic rituals by the locals in South America.

Mescaline is the primary psychoactive alkaloid found in San Pedro cacti. Peyote (Lophophora williamsii) is another notable psychoactive cactus with mescaline. North American natives have long used it for similar rituals and herbal medicine.

Medicine:

Cactus plants have been used for medicinal purposes for centuries by the native people of North and South America. The prickly pear cactus (Opuntia) is the most well-known for treating various physical ailments like skin wounds and inflammation.

The Indian fig cactus (Opuntia ficus-indica) has also been shown to lower blood sugar levels in rats. This suggests it could help treat diabetes and obesity in general.

Many types of cactus plants that have been used in traditional medicine for centuries are being put under the microscope to discover their capacity for use.

Research is being carried out to uncover the nature of their health benefits, and the results are promising.

Natural Fences:

Another use for cacti is as natural fences. This is often done in areas of the world where resources are scarce. Cacti fences deter animals and intruders while still looking aesthetically pleasing.

Cactus fences are often used in gardens and farms to keep animals out. They can also be used to create privacy screens or windbreaks.

The most common type of cactus used for this purpose is the columnar cacti from the Cactoideae subfamily, which like to be straight and upright.

Cactus Pictures Gallery

How To Care For Cacti

Cacti are forgiving plants. This fact is well-established and recognized by almost everyone that dabbles even slightly interested in gardening. These plants tolerate neglect well and are generally easy-care plants that don’t require much from the gardener.

However, there is a key difference between not requiring much and needing nothing. True, you can plant and forget about your cactus to middling results. But if you want a thriving specimen with a spectacular growing habit, you’ll have to put in a little effort.

There are two main categories of cacti when it comes to cultivation. Cacti have evolved to deal with semi-desert or drought conditions and epiphytic cacti. Most types of cacti or the ‘typical’ cacti fall under the semi-desert category. Therefore, we’ll mainly cover the needs of these cactus plants. However, do note that epiphytic cacti need a different care regimen entirely.

Light:

All cacti need some degree of sunlight to thrive. The amount of sunlight your cactus needs will depend on the species. Some cacti, such as the common desert cacti, can tolerate full sun for long periods. Others, like the subtropical epiphytes, need filtered light or dappled shade.

It is generally best to give too much sunlight rather than too little. Cacti exposed to too much sunlight can get sunburned, which manifests as brown or red patches on the plant’s skin, which is immediately apparent.

If your cactus is getting too much sun, move it to a location with less light.

A common misconception is that desert cacti don’t need shade. Depending on the species, this is simply not true. Even a true cactus or a typical cactus can’t tolerate direct sunlight all of the time.

Soil:

The type of potting medium you use for your cactus is essential. Cacti need their potting medium to have two main characteristics to be satisfactory: Good Drainage and Good Airflow.

Cacti need well-draining soil that doesn’t hold onto moisture too much. The best type of solution is to use a sandy or gravelly loam. You can also use a potting mix specifically designed for cacti and succulents.

There is some disagreement among gardeners on whether or not it’s okay to add organic material to a cactus mix. However, to be safe, use as little organic material as possible to promote better drainage.

If you’re unsure whether the type of soil on hand will work, simply do a test by filling a pot with the soil in question and giving it a good watering. If the water drains quickly, the soil is probably suitable. However, if the water stands on top of the soil or drains very slowly, it’s not ideal, and you should look for something else. Another option is to mix cactus potting mix with perlite or sand in a 1:1 ratio.

If you’re planting your cactus in the ground, ensure the location has suitable drainage. If not, consider growing your cactus in a raised bed.

Watering:

How often to water your cactus will depend on the size, type, and age of the plant and the climate conditions. In general, desert cacti need to be watered about once every couple of weeks during the growing season (spring and summer). Epiphytic cacti must be watered more frequently, about 2-3 times a week.

Avoid overwatering at all costs. No easier way to kill your cactus than to water it needlessly.

To water your cactus, simply give it a good soaking until water runs out of the drainage holes you’ve drilled in the bottom of the pot. Then, allow the plant to drain thoroughly, and don’t let it sit in water. If you’re uncertain whether your cactus needs water, it’s best to wait another day or two before watering again.

During the winter, most cacti will go into a state of dormancy and need very little water. Once every month or so should be sufficient.

Temperature:

Most cacti come from warm, arid environments and, as such, can’t tolerate cold temperatures for extended periods. Therefore, if the temperature drops below 40 degrees Fahrenheit (4 degrees Celsius), it’s time to bring your plant indoors.

The vast diversity in the Cactus family ensures not everything holds true for every cactus.

But in most scenarios, maintaining the temperature between 40-50 degrees Fahrenheit (4-10 degrees Celsius) is the safe zone. No cactus will die in this zone, and you’re generally safe.

Cacti also don’t like sudden temperature changes. So, if you need to move your plant indoors, make sure to do so gradually over a week or two. Giving the plant plenty of time to adjust to its new environment and avoid shock.

Some cacti are cold hardy while others are highly cold-sensitive. Find out which one your cactus is to care for correctly.

Fertilizer:

Cacti need very little fertilizer if any. If you decide to fertilize your cactus to promote early growth, use a very diluted solution of a balanced, all-purpose fertilizer and apply it once or twice during the growing season. Depending on the cactus species in question, you can also opt for the 5-10-10 or the 5-10-5 blend.

Follow the directions on the label carefully, as too much fertilizer can damage your plant.

Different types of cactus plants have different growing seasons. Some grow in the summer while others thrive in winter. Only fertilize your cactus when it’s actively growing. Fertilizing during the dormant period will have negative consequences far down the line and will most likely end up with stunted or disfigured cacti.

Overwintering:

During the winter months, most cacti will enter a state of dormancy. This is nature’s way of helping the plant survive in its natural environment where water and food are scarce. As such, you won’t need to water or fertilize your plant often. Once every month or so should be sufficient. However, you will need to ensure the temperature doesn’t drop too low as most cacti can’t tolerate cold temperatures for extended periods. If the temperature drops below 40 degrees Fahrenheit (4 degrees Celsius), it’s time to bring your plant indoors. When moving your plant indoors, make sure to do so gradually over a week or two to avoid any shock.

Propagation:

Cacti can be propagated by seed, cuttings, or by offsets.

Seeds:

If you want to propagate your cactus by seed, you’ll need to wait until the plant flowers. Once the flower blooms, it will eventually become a fruit containing the plant’s seeds. The fruit will mature and burst open, revealing the seeds embedded in a fleshy material. You can either sow the seeds immediately or store them for later use.

Take note that in some cases, a cactus may never flower indoors. For these types of cacti, the only option you have to grow them with seeds is to buy them from your local garden store. Depending on the rarity of the cactus, you might have to order the seeds online.

In most cases, cactus seeds need to be stratified to induce sprouting. Stratification means subjecting the seeds to a period of cool, moist conditions before planting. Anyone can do this by placing the seeds wrapped in a plastic bag in a fridge for about 4 to 6 weeks. This will induce the seeds to sprout into seedlings.

1. Once the stratification period is over, you can plant the seedlings in pots filled with well-draining potting mix.
2. Be sure to press the seeds into the soil lightly but don’t cover them with soil as they need light to germinate.
3. Water the soil lightly and place the pots in a warm, sunny location.
4. Keep a close eye on the soil and water when necessary.
5. The seedlings should start appearing within 4 to 8 weeks.

Cuttings:

Cactus cuttings are usually taken from a healthy portion of the stem.

1. To take a cutting, use a sharp knife or pair of scissors to cut a piece of the plant about 2 to 3 inches long.
2. You should take the cutting from a healthy part of the plant that’s free of any diseases or pests.
3. Once you’ve taken the cutting, allow it to callus over for a few days before planting. A dry, sunny windowsill should do the trick.
4. Once the cutting has callused over, it’s ready to be planted.
5. Fill a pot with a fast-draining potting medium (as discussed previously) and lightly water it.
6. Make a small hole in the soil and insert the cutting.
7. Pack the soil around the buried cutting and water it lightly.
8. Place the pot somewhere warm and sunny. Water when necessary.
9. The cutting should start to grow roots within 2 to 4 weeks. Once it has roots, it can be transplanted into a larger pot.

Offsets:

Not all cacti offset, but those that do can easily be propagated using this method.

Offsets are small plantlets or offshoots that form at the base of the main plant. They can be removed and transplanted into their own pots.

1. To remove an offset, use a sharp knife or pair of scissors to cut it away from the main plant.
2. Once it’s been removed, allow it to callus over for a few days before planting.
3. Follow the same process as the cuttings, and your offsets will begin to develop even faster into fully mature plants.

Common Cacti Problems:

Pests:

Cacti are relatively resistant to pests, but they’re not immune. The most common pests that attack cacti are mealybugs, scale insects, and aphids. These pests feed on the plant’s fluids and can cause damage to the leaves or stems.

Mealybugs are small, white, fuzzy insects that tend to congregate in groups. They can be challenging to spot, but if you see any white fuzzy stuff on your plant, it’s likely mealybugs.

Scale insects are small, hard-bodied insects that attach themselves to the plant and feed on its fluids. They tend to form colonies and can be found along the stems or leaves of the plant.

Aphids are small, soft-bodied pests that can be white, black, or green. They tend to congregate in groups and feed on the plant’s fluids.

If you see these annoying pests on your cactus, acting quickly is crucial as they can cause severe damage. The safest solution is to use insecticidal soap or neem oil, but harsher measures might be necessary in extreme cases.

Diseases:

Cacti are relatively resistant to diseases, but they’re not immune. The most common problems a cactus might face are root rot, crown rot, or stem rot, all caused by some variation of overwatering.

Overwatering is the biggest cause of dead cacti, so it’s essential to be careful not to do it. If you think your cactus might be overwatered, the best course of action is to let it dry out for a bit and see if that helps.

If you see any rot on your plant, it’s essential to act quickly, as any delays will only quicken a cactus’ death. The best way to deal with rot is to cut away the affected parts of the plant and hope that the rest of it survives.

Are Cacti Toxic?

Cacti are not toxic per se, but that doesn’t mean eating one won’t cause problems. Skin irritation, stomach aches, swelling, or itching are symptoms associated with cacti consumption.

The spines can injure the throat on the way down. Therefore, despite not being toxic, it’s generally not advised you attempt eating a cactus without prior research into its edibility.

Types of Cacti – Subfamily Cactoideae 

Tree-Like Cacti

These are gigantic and unbelievably tall cacti. They’re typically in the deserts and other wide open spaces where they get all the room needed to branch out. These cacti can get to enormous sizes if given a chance; the largest cactus in the world, Pachycereus Pringlei, falls in this category and has a maximum height of over 60 feet.

Mexican Giant Cardon Cactus (Pachycereus Pringlei)

The Mexican Giant Cardon Cactus or the Elephant Cactus (Pachycereus Pringlei) is the tallest free-standing cactus in the world. It can get as tall as 63 feet or 19.2 meters, all of its own. Notice the ‘free-standing’ addendum; some others types of cacti can get as tall as 100 feet but only ‘with support.’

Pachycereus Pringlei is native to the Baja California Peninsula in Mexico, but you can find it growing wild across much of Mexico intermittently.

Pachycereus Pringlei is exciting both for its size and its unusual appearance. The trunk is thick and stocky, with well-defined ribs that darken to black with age.

It grows mostly upright with frequent branching, resulting in a tree-like shape. The branching starts quite early, near the base of the stem, so this cactus looks less like some of the other Arborescent cacti.

Pachycereus Pringlei is also called the False Saguaro because it’s often confused with the Saguaro cacti because they are both quite large types of cacti.

The fruits were of incredible importance to the natives as a food source, but their use has fallen off with the advancing technology and better alternatives readily available.

Saguaro (Carnegiea Gigantea)

The Saguaro cactus (Carnegiea Gigantea) is the second tallest cactus in North America, only being topped by the Mexican Giant Cardon Cactus. It can get up to 40 feet tall and 12 feet wide with a trunk that’s incredibly thick!

If you’ve seen a wild west movie, you’ve seen a Saguaro. Remember the silhouette of the large cactus in the background of every Mexico ad ever? That’s a Saguaro; chances are, you’ve seen one without knowing what it was.

Carnegiea Gigantea is native to the Sonoran desert in Arizona but can grow wild across some California regions. However, unlike the movie industry’s impression, these types of cacti are scarce in Mexico (Though they are found there).

Regarding its growth habit, the Saguaro likes to grow like a tree. New ‘arms’ or branches appear almost midway along the length of the cactus and become nearly as thick as the main trunk.

Growth is slow, and it takes decades for a new Carnegiea Gigantea to reach halfway to its ultimate height.

The fruits are interesting in that they’re quite juicy. The Saguaro cactus is a popular ornamental plant in many areas and is used as a food source by Native Americans.

Cardon Espinoso (Pachycereus Weberi)

The Cardon Espinoso, or Pachycereus weberi, is a Mexican cactus species. With some specimens reaching up to 20 feet (6 meters) in height, it is one of the world’s tallest cacti.

The Pachycereus weberi has an enormous 3-foot (1-meter) diameter trunk. The plant’s tough, green exterior keeps it safe from the harsh sun and allows it to store water for extended periods. However, its body spines are also very sharp, so touch with caution.

The growth habit of Pachycereus weberi sets it apart from all the other types of cacti. The branches appear suddenly about halfway along the length of the trunk and extend sharply sideways and upward. The resulting Candelabra-like shape is unmistakable. In addition, the branching stems send out their own branches to further extend the shape to massive proportions.

The branches keep going sideways until they get space to go up and orient themselves upward. The outcome is stunning.

Pachycereus weberi requires a lot of space and exposure to direct sunlight if you want to cultivate it yourself. Nevertheless, you’ll have a prominent garden feature to write home about if all criteria are achieved.

Blue Myrtle Cactus (Myrtillocactus Geometrizans)

A cactus endemic to Mexico, the Blue Myrtle Cactus (Myrtillocactus geometrizans) can grow to be 15 feet (4.5 meters) tall and 16 feet (5 meters) broad.

It grows like a columnar cactus initially, but as it reaches critical mass, the main trunk starts giving off new and robust branches that extend in the shape of a candelabra (Like Pachycereus weberi but less packed together).

Myrtillocactus geometrizans stems are a white or slate-grey and green combination. They tend to be greener near the tips of the branches and more and more woody near the base.

Because it resembles an upright candelabra, Myrtillocactus geometrizans is also known as the Blue Candle Cactus.

Myrtillocactus geometrizans bloom in the summer and produce tiny greenish-white flowers that are so small that they are barely visible against the stem. The flowers develop into tart-flavored, red fruits that are edible though not very tasty.

The Blue Myrtle Cactus is a hard one to recommend to gardeners. It requires much care and attention in cultivation, and the payoff is years later.

Mexican Fence Post Cactus (Pachycereus Marginatus)

The Mexican Fence Post Cactus (Pachycereus marginatus) is popular in cultivation. Unlike some of the other Arborescent cacti, this one is perfectly suited to be used as a houseplant.

When Pachycereus marginatus is grown in a pot, it tends to stay between 4-5 feet tall. But in the wild, this height can easily reach 15 feet.

A common use still practiced today is using the Pachycereus marginatus as a fence post. Since it grows perfectly upright, multiple specimens can be grouped together to form a wall of cacti. The result looks spectacular and earned this plant its common name.

Remember that these cacti take multiple decades to grow as tall as they do in the wild, and it’s simply impossible to provide the same conditions for growth in cultivation.

Pachycereus marginatus is native to the Mexican Sonoran desert, where it grows quite commonly.

Pachycereus marginatus is a gray-green cactus with white spines along its length. On cultivated specimens, the spines are sharp and can easily injure if handled without gloves. Older cacti usually have shorter spines than younger ones.

Pink or green flowers appear in the spring. Then, as the season comes to an end, they turn into scarlet fruits.

Columnar Cacti

Fairy Castle Cactus (Acanthocereus Tetragonus)

The Fairy Castle cactus (Acanthocereus tetragonus) is a popular cactus for its unique columnar growth habit. Unlike other cacti, the stem of these flowering plants doesn’t grow in a solitary fashion. Instead, it gives many small branches that cluster around the main stem forming a miniature castle. 

This unusual growth habit gives the cactus a unique appearance that can be striking when displayed in a garden. It also lends itself quite nicely to being displayed in containers. So if you’re looking for an indoor cactus plant different from the rest, the Fairy Castle Cactus is a fair bet.

Acanthocereus Tetragonus stems have five ribs running along their length. White spines appear after small intervals all along these ribs. They’re slightly puffy with a wooly white appearance.

The Fairy Castle Cactus is native to parts of North America. It rises up to about 5 feet tall and features prominently in traditional folk art from this region.

The Fairy Castle cactus is a popular specimen for cacti collectors and can be found at most garden centers.

Compass Barrel Cactus (Ferocactus cylindraceus)

The Compass Barrel cactus (Ferocactus cylindraceus) is a cacti species with a distinctive barrel-shaped growth habit. It is native to parts of the United States (mainly California) and Mexico, and at no danger of extinction, the IUCN red list confirms.

The stem of Ferocactus cylindraceus typically grows in a robust column with many ribs running along its length. Interestingly enough, the column formed by each and every specimen of the Compass Barrel Cactus leans south as it ages. This behavior earned this plant its common name.

This unusual growth habit makes Ferocactus cylindraceus perfect for displaying in large containers or yards. It’s also one of the more compact cacti options, which can be easily accommodated indoors if desired.

The spines are particularly sharp on young specimens of a Ferocactus cylindraceus, so handle with care.

Silver Torch Cactus (Cleistocactus strausii)

The Silver Torch Cactus, Cleistocactus strausii, belongs to the cactus family and is a perennial bloomer. It grows on high-elevation rocky areas in Bolivia’s southern provinces.

Along with being called the Silver Torch Cactus, these types of cacti are also called Wooly Torch Cacti, a reference to the white wool-like hair that covers them from root to tip.

Highly ribbed cylindrical stems cover the tall, single file columns reaching up to 10 feet in the wild. In cultivation, Cleistocactus strausii tend to stay small enough to stay in their containers, but with proper care, they can grow taller.

Red flowers grow perpendicular to the stem near the apex to break the monotony of the otherwise uniform silver coloration of Cleistocactus strausii. In addition, the red flowers stand out quite nicely against the silver backdrop.

Old Man Cactus (Cephalocereus Senilis)

Old Man Cactus is a unique cactus. It gets its name from the long, white hairs that cover its body, which make it look like an old man with a beard.

Cephalocereus Senilis grows out of the desert in Mexico. In its native habitat, it can rise up to 40 feet tall, with a main solitary trunk that gets around a foot wide at maturity. These cacti lend themselves well to cultivation but don’t grow as tall indoors or in a pot. Cultivated specimens tend to stay within the maximum 4-10 feet range.

Cephalocereus Senilis is a member of the genus Cephalocereus, which are almost always columnar cacti. The species name Senilis means “old man,” referring to its wooly white hair covering the entire plant’s stem. This coating of white hair is startling to behold and adds lots of texture to a garden setting, standing out quite nicely in a sea of greens.

The hairs covering the stem are modified spines that developed rein this way to help these cacti survive the harsh extremes in the weather. In addition, 20-30 ribs cover the surface of the stems with the white hairs coming out of the areolas.

Peruvian Apple Cactus (Cereus Repandus)

Cactus fruit is one of the most interesting parts of a cactus plant. While they’re mostly decorative and make great focal points in your ornamental landscape, they can also be delicious!

Cereus peruvianus, or more accurately Cereus repandus, is a great addition to any garden for its tall columnar habit.

But what sets this cactus apart from other cacti? Well… it’s the fruit! When ripe (which usually happens during fall), these fruits turn into edible dark purple berries! This fruit looks starkly similar to an apple and is therefore known as a Peruvian Apple fruit or just Peruvian Apple.

These delicious fruits are the main reason these types of cacti are cultivated. Appearance-wise there is nothing separating these cacti from hundreds of other species; the same dull green color and thorny spines protrude from deeply ribbed stems. If not for the fruits, these cacti would see much less popularity.

Yellow Tower Cactus (Parodia leninghausii)

The Yellow Tower Cactus, Parodia leninghausii, is a cactus that grows in the wild in Argentina. It is named after its distinctive yellow flowers, which appear on its branches during summer. The Yellow Tower Cactus is also known by various other names such as Golden Ball Cactus or the Lemon Cactus.

Parodia leninghausii grows up to 3 meters tall (around 1 meter) with a strong, solitary cylindrical stem. These stems start out globose but extend into a tall cylinder with age. It has long spines that are the main identifying feature of this cactus. Their white-gold coloration sets this cactus apart from all the rest.

Parodia leninghausii is called the “Yellow Tower Cactus” because of its bright yellow flowers, which arise from the apex of adult specimens. These flowers give off a sweet smell when they bloom during the summer months. Then, they develop into globose fruits.

Echinopsis pachanoi (San Pedro cactus)

The Echinopsis pachanoi, a.k.a. the San Pedro cactus, is a fast-growing columnar cactus native to Peru and Ecuador, though you can also find it in the surrounding regions.

It can rise up to 20 feet (6 meters) tall and has greenish-grey (glaucous) skin with prominent white spines. The plant contains psychoactive alkaloids and has been used in shamanic rituals by the region’s indigenous people for centuries.

This cactus is often used in landscaping and gardens as it is easy to care for and drought tolerant. It can, however, become a nuisance as it spreads easily and can take over an area if left unchecked.

The San Pedro Cactus has been used medicinally to treat a wide variety of ailments, including stomach problems, anxiety, depression, and even cancer. The plant is also considered sacred by some indigenous cultures which use it in spiritual ceremonies.

The name San Pedro Cactus translates to Saint Peter, the saint mentioned in the Christian religion.

Globular Cacti

Pincushion Cactus (Mammillaria)

Pincushion cacti are a group of mostly spherical cacti native to some parts of the United States, South America, and the Caribbean. They are known for their pincushion-like shapes and colorful flowers, which often have a pink or red hue.

Most species in the genus have a high density of tubercles and spines, giving them a hairy appearance. 

Notable examples include the Powder Puff Cactus (Mammillaria Bocasana), the Old Lady Cactus (Mammillaria hahniana), and the Feather Cactus (Mammillaria plumosa), and the Rose Pincushion Cactus (Mammillaria Zeilmanniana). These species have colorful blooms and are relatively easy to grow in home gardens.

The Powder Puff Cactus has a large rose or cream-colored blooms that arise from the apex of the stem. This item is covered with a soft layer of white spines. This variety stays small and is perfectly suited as a desktop plant. 

The Rose Pincushion Cactus has a similar overall shape to the Powder Puff Cactus but has a twist. The upper body of the stem is covered with a ‘crown’ of flowers. This is a circular band of red flowers that covers the upper stem. The beautiful flowers are the main reason these types of cacti are popular. 

The Old Lady Cactus (Mammillaria hahniana) is also a small globular cactus with a thick coating of coarse white hair across its surface.

The Feather Cactus (Mammillaria plumosa) is covered with soft white hair. The clustering habit of this cactus ensures the uneven shape of the globe. Solitary stems are globose.

Sea Urchin Cactus (Echinopsis)

Sea Urchin Cacti, belonging to the genus Echinopsis are some of the more popular Cacti in cultivation.

Some types of these cacti are also referred to as Hedgehog Cactus or Easter Lily Cactus. A significant number of Echinopsis are globose, which means they have a spherical shape with little to no growth. This results in a ball-like shape and adds many cacti from this genus to the category of globular cacti.

Do understand that some species in the Echinopsis genus aren’t small and globose but large and columnar. However, a significant portion still strongly resembles a sea urchin with a dense covering of spines on a globular shape, hence the name.

Echinopsis is an amalgamation of a few different genera, most notably Trichocereus and Lobivia. Cacti that used to belong to Lobivia tend to be on the smaller side and are what we understand as the small globular Sea Urchin Cacti of today. Trichocereus, on the other hand, tend to be bigger and somewhat more columnar than their cousins, resulting in a drastically different shape.

Crown Cactus (Rebutia)

Rebutia is a genus of small cacti that are native to South America. They are some of the most colorful cacti, with blooms in shades of yellow, orange, red, and pink.

These cacti are relatively small, with most species staying under 10 cm in height. They tend to be globular, with a dense population of offshoots surrounding the main plant.

If you find a Rebutia, it will almost always be accompanied by many offshoots forming an uneven clump. This clumping habit makes Rebutia quite easy to propagate and helps them stand out from the rest of the cacti.

Unlike some other globular cacti, Crown Cacti are all quite small. They’re dwarf cacti that are incredibly suited for container cultivation.

The flowers of Rebutia cacti arise from the sides of the plant body instead of the apex and are usually very colorful. After blooming, these flowers will develop into small fruits that contain seeds.

Rebutia fiebrigii is the most well-known example of Crown cacti.

Golden Barrel Cactus (Echinocactus grusonii)

The Golden Barrel Cactus, Echinocactus grusonii, is one of the most popular cacti on the market. It has a long barrel-like stem that can get around 2-3 feet in diameter.

Golden Barrel cacti are members of the cactus family and grow in the Southwestern United States and Mexico’s arid regions. These types of cacti are easy to identify because of their characteristic golden barrels or swollen stem tips that often have a brownish tinge.

The main identifying feature of the Golden Barrel Cactus is the prominent ribs bearing the golden yellow spines. These spines’ color is the most eye-catching part of the cactus. Especially when contrasting with the green color of the stems, it looks gorgeous.

Echinocactus grusonii flowers are yellow and grow from the apex of the stems.

Golden Barrel cacti are one of the most popular types of cacti for gardeners because of their striking appearance; this is a texture cactus-like no other.

Star Cactus (Astrophytum Asterias)

The Star Cactus is a small cactus that is native to Mexico. It gets its name from the star-shaped patterns that cover its body. These patterns are raised tubercles that have a white color.

The plant body of a Star Cactus is small and globular in shape. It typically reaches a height of around 5 cm with a diameter of 10 cm. The overall shape is quite flat, differentiating it from other spherical cacti.

The surface of the Star Cactus is completely devoid of spines. Instead, small white dots cover the entirety of the stem body resulting in a beautiful shape. Tufts of white wool rise from the large tubercles.

Interestingly, Star Cactus is also called Sea Urchin Cactus, which is a common name you’ll find assigned to lots of different globular cacti. It’s also called the Sand Dollar Cactus in some circles.

The yellow flowers bloom in the summer and are so large in relation to the body that they often dwarf the Star cactus entirely.

Another notable example of globular Astrophytum includes the Goat’s Horn Cactus (Astrophytum Capricorne).

Scarlet Ball Cactus (Parodia haselbergii)

The Scarlet Ball Cactus (Parodia haselbergii) is a popular cactus that grows in the temperate region of Brazil.

Parodia haselbergii is a small, spherical cactus with a diameter of up to 15 cm and spines of short, silvery-white spines. It actively grows from the winter to spring and is threatened in its local habitat by overgrazing.

The Scarlet Ball Cactus is spherical, more or less flattened, bright green, and almost completely concealed. The surface is marked with a thick layer of spines, hiding the stem underneath.

Red flowers appear from the apex of the stems and get quite large compared to the stem. Their red color earned this cactus the Scarlet Ball moniker.

Like many other spherical types of cacti, the Scarlet Ball cacti tend to offset quite profusely from near their base. They have a clump-forming habit that sees them occupy the space they are given.

Other notable Parodia species that are also globular cacti include; the Indian Head Cactus (Parodia ottonis) and Tom Thumb Cactus (Parodia mammulosa).

Bishop’s Cap Cactus (Astrophytum myriostigma)

The Bishop’s Cap cactus is a small, globular cactus native to Mexico. It gets its name from the spines that cover its body and resemble the caps worn by Catholic bishops. It is also called the Bishop’s Miter for that reason.

The plant body of the Astrophytum Myriostigma is small and globular in shape. It typically reaches a height of around 5 cm with a diameter of 10 cm. The overall shape is quite unique, with five distinct ribs that protrude outward and form distinct rims around the base plant.

Spines are nowhere to be seen on the Bishop’s Cap Cactus. Instead, the ribs are covered with slightly raised spots that appear intermittently along their length.

In some cases, the body of these cacti is covered with white spots on the entire body.

This cactus is incredibly popular in cultivation due to its unique shape and easy care requirements.

Balloon Cactus (Parodia magnifica)

The Balloon Cactus (Parodia magnifica) is a globe-shaped cactus native to Brazil. It has a green body with white spots and can grow up to 12 inches in diameter. The Balloon Cactus gets its name from its shape, which resembles a fully inflated balloon.

Parodia magnifica is a perfectly symmetrical cactus with distinct ribs lined with spines. The stem is colored a bluish-green color which contrasts beautifully with the yellow gold spines.

Parodia magnifica is not only round but also incredibly spiky. It has long, sharp spines that can grow up to 2 inches in length. They’re so sharp that they can easily puncture the skin and cause serious injury. So be careful when handling this plant!

The Balloon Cactus blooms in the spring and summer months. Its flowers are yellow or orange and have a diameter of up to 2 inches. They only bloom from the apex of the stem and are radiant when they appear.

Other Forms

Cacti that don’t fall into the abovementioned categories tend to be relegated to this one. This includes epiphytic cacti, scalloped or sectioned cacti, and most Opuntia (Prickly Pear Cacti) since they tend to differ from every other cactus.

Most notably, plants of the genera Leuenbergeria, Rhodocactus, and Pereskia belong to the cactus family but look nothing like any other cactus.

Instead, these plants blend into their environments and mimic other plants in their local habitats, like the shrubs and the trees. Unfortunately, this results in frequent misidentification as the plants in these species are not immediately recognizable as cacti.

Orchid Cactus (Disocactus Ackermannii)

The Orchid Cactus (Disocactus Ackermannii) is a tropical cactus native to Mexico and Central America. Its called the Orchid Cactus because of the shape of its flowers, which resemble orchids.

This is an epiphytic cactus, which used to grow without soil and by climbing onto supporting structures. This is quite different from typical cacti, as it can make for an interesting display if you let it climb up a trellis or something similar.

The Orchid Cactus’ main feature is its large red flowers. These funnel-shaped flowers are usually some shade of red emerging from the center of the cactus.

Unlike regular cacti with thick leafless stems with ribs and spines, the Orchid Cactus has scalloped or sectioned leaf-like structures and a solitary main stem that remains relatively short. The scalloped ‘leaves’ are wholly flat and spread out in a rigid cascading effect. When the large red flowers are in full bloom, these leaves form a green backdrop, further accentuating the brilliant red color of the flowers.

Holiday Cactus (Schlumbergera)

The Holiday Cactus (Schlumbergera) is a plant that most people are familiar with. It’s the type of plant you often see for sale around that holidays, hence its common name. It is a small genus in the Cactus family.

This plant is native to the coasts of Brazil, where it grows as an epiphyte (a plant that grows on other plants). It’s the genus of the Thanksgiving Cactus, the Easter Cactus, and the Christmas Cactus, all of which bloom around their respective holidays. All three plants are significant commercial Schlumbergera species.

The Christmas Cactus (Schlumbergera x buckleyi) is especially important since many people look for winter blooming flowers around that time. That’s when the Christmas Cactus come in handy.

The Holiday cactus has segmented stems that are flat and leaf-like. The main differentiating factor between the Christmas Cactus and the Easter Cactus, for example, (other than the blooming season) is how their leaves are sectioned.

Rat Tail Cactus (Aporocactus flagelliformis)

The Rat Tail Cactus (Aporocactus flagelliformis) is a cactus native to Mexico. Its called the Rat Tail Cactus because of the long, thin, rat-tail-like stems that hang down from the main plant. 

The Rat Tail Cactus is a medium-sized plant that likes to stay small for much of its lifetime. It doesn’t grow much taller than 4 feet, but it can easily be pruned to remain shorter.

Its thin, rat-tail stems like hand down and cascade from any container it’s given. This makes these cacti perfect for hanging baskets and potted containers.

The bright pink flowers contrast nicely against the soft green stems. They are somewhat large (not overly so) but only last for a couple of days when they appear in late spring.

Starfish Cactus (Orbea variegata)

The Starfish Cactus (Orbea variegata) is endemic to Central America and parts of Mexico. It’s called the Starfish cactus because its flower shape resembles a starfish. 

These flowers are the main feature of this cactus, earning this plant’s infamy among gardeners. 

You see, these leopard-printed flowers might look pretty, but they smell anything but. Instead, they give off a pungent, disgusting odor that stinks a room like nothing else. 

For cultivation purposes, Orbea variegata are rarely kept as indoor cacti. Instead, you’ll most likely see them on a patio or deck.

The yellow flowers are dotted with brown leopard spots that make these cacti attractive. 

Peanut Cactus (Echinopsis chamaecereus)

The Peanut Cactus, also known as Echinopsis chamaecereus, is a small cactus native to Bolivia. It’s closely related to the Easter Lily Cactus (Echinopsis subdenudata).

Although it belongs to the Echinopsis genus, which consists mainly of globular cacti, this one is an exception to the rule.

The Peanut cactus gets its common name from the shape of its stem, which is so small it resembles a peanut.

It’s a very slow grower, only reaching about 6 inches in height at maturity. But it can spread up to 12 inches wide due to its clustering habit. The stem is green and cylindrical with short spines. Multiple branches appear near the main stem quite frequently and cascade out of the pot.

The flowers of the Peanut Cactus are white with yellow centers and appear in the springtime. They only bloom for one day, but they’re quite beautiful while they last.

Moon Cactus (Gymnocalycium mihanovichii)

The Moon Cactus (Gymnocalycium mihanovichii) is a small cactus that only grows about 2-3 inches (5-8 cm) tall. It’s a weirdly shaped cactus with a round umbrella top, shaped like a sphere cut in half. The plant’s body is green, but the top is often brightly colored. The colors can range from pink to red, yellow, and everything in between.

The Moon Cactus’s bright colors result from a lack of chlorophyll. As a result, the portion with the bright colors can’t photosynthesize and would die without the green bit below it helping it along.

The Moon Cactus gets its name from its shape and its coloration. It looks like a mini-moon, with a “crater” at the top. And the bright colors make it look even more otherworldly.

Every Moon Cactus is a result of grafting two cacti together, the Gymnocalycium mihanovichii and a Hylocereus species. The Gymnocalycium mihanovichii forms the ‘scion,’ i.e., the colorful portion at the top, and the Hylocereus forms the rootstock, which is the green portion that props up the colorful part.

The Moon Cactus is a popular plant for its small size and bright colors, making it a perfect addition to any windowsill or tabletop.

Subfamily Opuntioideae

The Opuntioideae subfamily is one of the largest groups of cacti, with over 200 species in total. They’re often referred to as ‘Prickly Pear Cacti,’ because many (but not all) members of this subfamily have flattened pads that resemble pears (hence the name).

Prickly pear cacti are very diverse and endemic to various habitats. Their sizes are also quite variable, ranging from shrubs to trees.

However, what defines a Prickly Pear Cactus are its pads. These pads are even sometimes edible (most notably in the case of Opuntia ficus-indica) but not always. They are often used in Mexican cuisine by the locals.

Bunny Ear Cactus (Opuntia microdasys)

The Bunny Ear Cactus (Opuntia microdasys) is a type of cactus that gets its common name from the shape of its pads, which resemble the ears of a bunny rabbit. It’s native to northern Mexico and can also be found in the wild in other parts of America (primarily Arizona).

Opuntia microdasys is not particularly big, only reaching about 2 feet (60 cm) in height. The pads are generally green but sometimes have a reddish or purplish tinge. They’re also covered in small miniature spines (glochids) that only rise a couple of millimeters above the surface. All you feel when you touch them is a rough texture, but don’t go touching them as these fragile dots tend to dislodge into the skin if touched.

All Opuntia have a roughly similar shape with oval pads covered in white or yellow polka dots. They range from incredibly large to very small, but the overall shape remains the same. This shape is so unlike any other cactus that there is no confusion regarding which cactus belongs to the Opuntia genus.

Subfamily Pereskioideae

Leuenbergeria

Leuenbergeria is a relatively new addition to the Cactus family. It was named after Leuenberger, a notable botanical curator of Swiss origin. Joël Lodé was responsible for naming the genus so in 2012.

Previously, the Leuenbergeria genus was a part of Pereskia. But more on that later.

Plants in the Leuenbergeria don’t resemble other types of cacti. They look more like a green bush than anything else. They grow in the shape of a tree or a bush, depending on the species.

They have leaves that perform photosynthesis, stems that develop into barks, and branches that extend outward like regular trees. Some species can grow over 15 feet (4.6 meters) in height.

The flowers of Leuenbergeria are large, colorful, and beautiful. They come in shades of orange, pink, and red, but yellow flowers are the most common. The blooming period varies from species to species.

The only way to connect Leuenbergeria to other types of cacti is their areolas and spines. But even the areolas develop into leaves, masking the spines underneath.

Pereskia

If you saw a Pereskia growing on a sidewalk, you’d be surprised to learn it’s a cactus. These cacti are so unlike other cacti that it’s hard to tell they belong to the family.

All Pereskia are shrubs or trees ranging from 3 to 10 feet high with persistent leaves. They grow like trees and look like trees, and you really have to stand back and study them to realize they’re not trees but highly modified cacti.

The leaves are persistent and succulent, storing water instead of the stems and carrying out photosynthesis. The stems develop bark over time and don’t have any way to photosynthesize as they lack stomata.

There are only four plants in the genus, but they used to be much more. The genera Leuenbergeria and Rhodocactus were a part of the Pereskia genus for a long time, their main common feature being their tree or shrub-like growing habit.

However, later studies revealed Pereskia plants to be paraphyletic, which saw the plants from the other two genera removed from the Pereskia genus and placed into their own.

The most notable species from this genus is Pereskia aculeata, used to treat skin wounds and inflammation by the locals in Brazil.

Rhodocactus 

Like Pereskia, the Rhodocactus genus plants have a tree-like growing habit. They are cacti, but they sure don’t act like it.

They have persistent leaves that stay even after the plant fully matures, unlike most other types of cacti. However, they do have slight differences from Pereskia and Leuenbergeria, allowing you to differentiate them.

First off, their stems develop bark much, much later in life than both Pereskia and Leuenbergeria. And even when they do, they retain their stomata and the ability to photosynthesize.

Even their areolas develop much differently from other plants in the Pereskia genus, which helped scientists separate the two genera.

In Rhodocactus, the areolas are called ‘Spur Shoots’ or ‘brachyblasts’ and are their main identifying features. Instead of only forming a single leaf from the areola, a new shoot emerges with its own areolas, spines, and leaves. This branch is accompanied by sharp spines that crowd the areola and produce a distinctive appearance.

Subfamily Maihuenioideae

This subfamily is the smallest subfamily in the Cactus family, only including two species.

The Maihuenioideae subfamily is unique because the plants included in it don’t look or act like cacti. Instead, they’re more closely related to the Pereskioideae subfamily than any other cactus.

Both species in the subfamily are native to Chile and Argentina. One of the species is Maihuenia patagonica and the other is Maihuenia poeppigii.

What Is The Difference Between Cacti and Euphorbias?

Although cacti and euphorbias (commonly known as spurges) share a lot of similarities, they are, in fact, two very different plants.

The main difference between cacti and euphorbias is that cacti have specialized structures called areoles which Euphorbias lack. These areoles are essential for the plant’s survival as they help it store water and protect it from the hot sun.

Cacti have spines, while Euphorbias have thorns. Spines are modified leaves, while thorns are modified stems. It might not be easy to tell the difference between the two by looking, but it’s there.

Cacti also tend to have thicker, fleshier stems than euphorbias which helps them to store even more water. The extra water storage is necessary as cacti often grow in hot, dry climates where water is scarce.

Euphorbias, on the other hand, tend to grow in cooler, wetter climates. As a result, they don’t have the same water storage capabilities as cacti, but they make up for it by being able to store more nutrients in their leaves.

So, while cacti and euphorbias share a lot of similarities, they are, in fact, two very different plants. If you’re unsure which plant you’re looking at, remember that cacti have specialized structures called areoles, and Euphorbias do not.

FAQ

References:

1. Toxic and Non-Toxic Plants. ASPCA
2. RHS Award of Garden Merit. RHS
3. International Union for Conservation of Nature. IUCN