How To Identify Different Kinds Of Cactus Plants

The cactus is a weird shaped plant, alright, but how can you tell one cactus from the other? There are thousands of cacti species in the world and some look distinctively similar. A closer look will reveal the various features that set them apart.

The world is a jungle of cactus plants, their presence occupying almost every other continent. The Cactaceae family is most endemic in South America, Africa, and the drier parts of the Mediterranean. The cactus is a family name, which encompasses a plethora of about 2000 cacti species and 87 genera. When you next take a look at cacti species, you get to realize that they come in different forms, shapes, and sizes.

So, how can you tell apart the different species of cacti? This all boils down to the physical and internal characteristics of the the plant. To tackle this identification problem, behold is a list of traits to pay attention to while trying to make out the differences between cacti species;

  • Flowering style
  • Seeds
  • Fruits
  • Size
  • Shape
  • Spines
  • Stems
  • Geographical location

Defining the morphological differences between the different cactus species is a big deal for cactus enthusiasts and botanists. This guide has been coined to help ease your troubles by looking into the factors to look out for when differentiating the various cactus types. Whether this is for your self-gratification or vocational purposes, telling apart this deceptive species requires keen observation and understanding of botany and is definitely worth getting a medal for.

Where is the difference?

To the inexperienced, beginning to comprehend these differences can seem tedious and nearly impossible. These taxonomic differences arise from the species’ different morphological presentations. These differences inspire a conclusive comprehensive narrative on how to identify these desert species. Having a panoramic glance sweeping across the desert, you are bound to count cacti in their numbers at any given time. Cacti bear striking semblance with each other, yet they are different- probably not even in the same species. Cacti are the desert hardcores that thrive on the bare minimum. These plants are made to survive the hot inclement weather. They are leafless, which helps to keep transpiration rates at a minimum. The leaves are in fact, modified into tufts of thorn bristles and spikes. These survive as a protective mechanism to shoo away herbivores and destructive humans. Since water is such a rarity in the desert, cacti have fleshy succulent barks that act as their water storage reservoirs.

To propagate the progeny, cacti produce flashy, brightly colored flowers that attract desert pollinators. Some species of cacti are a great breed with their seeds, bearing seeds in their thousands inside the fruits. These xerophytes are shallow-rooted with tap roots that rapidly absorb the moisture before it leaks deeper into the grounds and beat evaporation. Bearing these phylogenetic characteristics in mind, differentiating cacti from other succulents is a mere stroll in the park. The arduous task is to help differentiate the species within the same family.

1.         Check out the sizes

Size is an important pointer that can help to distinguish these ridiculously similar plants easily. Some are tall plants, while others remain short, spiny but aggressive on the ground. The majority of the species are shrubs, growing to about 2 m in height. Blossfeldia species, for instance  are small in stature with a maximum circumference of 12 mm. The family diversity is so imminent, keeping in mind that the tree-like 10 m tall Browningia species falls in the same group as the dwarfyBlossfeldia. The mighty saguaro tree Carnegiea cacti, the wild west’s epitome, on the other hand, towers the desert skies with gigantic heights (50 ft tall) and offers reliable shades to desert animals.

 The fact that there are tiny species doesn’t mean that their ability to survive the wild is diminished. These short, overlooked species tend to have profusely prominent features. For instance, the diminished Cleistocactus bears numerous spines and brightly colored flowers, fully optimizing protection and reproduction.

2.         You can never go wrong with the shapes

Cacti are one of the most adaptable species considering the bizarre shapes they grow in, some that you wouldn’t imagine on living plants! Their shape diversity can help illuminate the cloud of ignorance surrounding the cacti family’s deceptive and uncanny similarities.

The peculiarity in nature never ceases, even in a desert scenario. Some species undergo a spectacular metamorphosis, one that includes a change in shape as the plant matures. For example, the Geohintonia species is globular when younger, but as it progresses into older age, the plant becomes columnar.

Cactus plants feature different shapes, including cylindrical, columnar, spherical, star-shaped, and others.

Most cacti species are either fleshly cylindrical trunks or stubby globular plants, or even star-shaped. While these are the most common shapes associated with cactus, a unique member of the Hylocereus species grows in a winding manner, climbing their way up tree trunks. They are epiphytes growing in moderately fair weather conditions. An even more baffling genus is the flat-like mat growing Maihuenia cactus. Its stem segments form cushions on the ground.

Then, there is the highly romanticized barrel-shaped Ferocactus species assumed to offer quick relief for a parched desert wanderer because of the barrel-shaped tank we assume has water. The Cephalocereus species, on the other hand, are large and columnar.

The other distinctive feature is its accordion-like ribbed trunk. While having these ribs is not only aesthetically pleasing, they act as water storage pockets for these plants. However, not all cacti species feature ribbed trunks. A famous player on matters ribbed trunks is the Cereus species, which stands out with its 5 to 10 properly defined ribs.

3.         What about the Leaves?

Leaves are a rarity amongst the cacti family. Seeing leaves on a cactus can help rule out almost 90% of the entire cacti family, as it is a rarely observed phenomenon. Even in cases where leaves are present, they are minor and diminished.

Since the majority of cacti do not feature leaves, you can easily determine the species of a plant if observing the leaves.

In fact, most of these leaves can only be spotted when there is a new growth emerging. You can easily differentiate the different cacti species by its ability to grow leaves, either at the seedking stage or when growing new sections. Still, some do not grow any irrespective of its growth stage.

4.         A look at the spines

The vicious spines protruding from their fleshy stems and even fruits is a typical characteristic of most cacti plants. While most cacti species bear this defining characteristic, others like the Ariocarpus do not spot any. If you can spot spines on them, the chances are that you have narrowed down your categorization to a given cacti.

 The spines can be thin or stout, scarce or dense, and these depend on the specific plant morphology. Some cactus types feature crooked hooks while others are straight as we know them. They can either be hair-like, pectinate, or bristle-like depending on the type of cactus in question.  Some cacti types feature spines that appear shiny owing to the waxy sheaths that coat their spine frames. Still others are rough and dry. While spines in some species grow anywhere on the plant without any precise symmetry, some more organized species sprout spines only on the ribs.

Observe cacti spines to determine the species of your plant.

Areoles are found in highly specialized branches or shoots; they are points from which spines arise on the stem. Some cactus types like Frailea features spines that are so weak and frail that they possess little to no threat against your fingertips.

A number of cactus species are blessed enough to bear colored spines. Some can even assume alternating patterns. There is also a unique tendency for younger cacti to grow numerous spines that slowly reduce in number as the plant ages.

5.         Stems can give a hint

Want to tell two cacti apart? It is probably all in the stem. The stems can either be smooth, littered with spines, ribbed, or at least have areoles emerging from them. Some areoles can be closely spaced, while others are neatly packed against each other. Areoles are the emergence points for spines. This presentation gives the impression that a plant has a jointed stem or not.

Take a look at the Tubercles when trying to tell apart some cactus species. These are warty growths that sprout on any outer part of a plant. The rounded projections arise from the cactus stem. While round tubercles are a more common feature in most cacti, triangular tubercles exist on some members of the Leuchtenbergia species.

6.         The Flowers can tell a story


One of its most peculiar features about cactis  is how they flower. They bear slight semblance to angiosperms, blooming out brightly colored large flowers while others have pale colors.

Cactus species produce flowers of different colors, allowing you to easily determine the type of your plant.

In some cacti species, flowers may fail to emerge and are hereby termed as cleistogamous. Such rare cacti species rely on self-pollination. Cacti flowers come in a variety of colors depending on the cacti type. They can range from deep hues of blue to an electric pink array of color. It is also worth noting that some cacti  flowers are duotone;  they feature two colors- one color towards the outer parts of the flower and the other towards the center.

Blooming habit

You can easily tell cacti types apart based on their blooming habits, timings and seasons. An even more spectacular trait is the nocturnal blooming characteristic associated with some of these desert cacti flowers. Most of them are night bloomers, but should they bloom in the heat of the day, they will open for only a short period. The flowers bloom at night when the transpiration rates are subdued, and daytime heat that can easily scorch these flowers to their death has subsided.

The other feature takes into consideration the aspect of time and season. Cacti have different flowering times depending on whether the plant is seasonal, annual, biannual, or perennial. In hindsight, one can differentiate a flower based on the time they blossom. They may also blossom for some given time during the day till they wither and fall off.

Position of the flower on the plant

You can tell a cactus’ species by the position of the flowers. Some tend to bloom flowers on the plant’s apex, while others have their flowers growing on the barks or stems. Other flowers like those from the Chin cactus are naked because they grow without any bristles, wool, or spines.

Fragrance and floral parts

 Some cacti flowers happen to be pleasantly fragrant while others produce flowers with pungent or strong smell. Some cacti flowers can be delicate and frail while some species boast large conspicuous flowers. The flower tubes may be either hairy or naked and least expected spiny, each unique variation giving the species a competitive edge for survival in the desert.

Flower shape

Depending on the species, the flowers can assume different shapes. These can range from cup-shaped to tube-shaped, star-shaped and funnel-shaped flowers.

7.         They just appear different from most of the plants you’ve seen before

Here is a bonus point with a lot of truth in it.This is not to say that any unfamiliar spiny plant growing along the road is cactus, but have you seen the Ariocarpus species? To a majority of people, these species will appear surreal and alien. These geophytes resemble the stones on the ground as if to mimic an actual land feature. They are quite a marvel to behold. In extreme conditions, these plants appear almost dead; they grow laterally on the ground and are firmly rooted on the ground with the help of the long tap roots that they possess.

8.         Take a look at their fruits


Different types of desert cacti have fruits that are a product of successful fertilization amid climatic adversities. Each species has its own color pigmentation on the fruit and this helps to tell them apart. While most cacti fruits can be green when raw, they eventually turn into a myriad of colors when ripe and this may range from yellow to black and even red. The fruits are hardly an average presentation of the usual.

Fruit-bearing cactus species can be recognized by observing the color of the fruit.


While some may have the familiar rounded shape, some species make their fruits a little more dramatic; for instance, the Epithelantha fruits are long erect tubes with conspicuous bright red color that you cannot to conceal. Some fruits may resemble pineapples. This happens when the plant species retains the dried parts of the flower on the apex of the elongated fruit. Then there exist other unique fruit manifestations that are club-shaped and have bracts.

Fruit skin texture

The fruits can either be smooth-skinned or have bristles pointing out from them. These glochids prevent the fruits from being easily foraged by animals and other predators. Being hard enough to keep the progeny alive through reproduction makes total sense to have some of these cacti species protect their fruits, conceived in these harsh weather.

The fruit’s insides

The physical appearance of cactus fruits can be deceiving, take a look inside. This is when you can easily differentiate one cactus fruit from another. When observing the insides, they may appear to be fleshy and juicy, while others can be dry. For species such as Harrisia, fruits can be a vital identification factor. Some species such as the Dragon fruit of the Hylocereus species bear big exotic fruits, while other species feature relatively small fruits. The truth is that much as the fruit contents may appear appealing and palatable, it is safe not to judge by the appearances.

The inside of a cactus fruit tells you more about the species of your plant.

9.         What’s to say about cactus seeds?

It may seem like a rather far-fetched way to bog down the differences, but it still is a significant one nonetheless. Cactus seeds can have smooth, shiny exterior or appear rough and hairy depending on the cactus type.  These seeds can either be foveolate or reticulate. As most cacti bear fruit berries, this means that fruit, if ripped open, contains countless seeds which can either appear black or brown.

10.      Are they solitary, or do they grow in a group?

Cactus growth patterns can help offer some insight into what kind of cactus species they are. Some, like the giant Saguaro cactus grow in solitude as if in isolation while others like members of the Echinocereus species tend to have their stems growing out in piles of hundreds. They grow out as a closely-knit cluster. 

One of the reasons that might explain this distribution pattern is a species’ pollination technique or characteristics. If the seeds are heavy, they will most likely drop off closest from the source, and if they are numerous and lucky enough to germinate, so will see the tufty shrub emerge.

11.      Geographical location

Sometimes the answer is right there with us. The native grounds on which these cacti grow can aid significantly in their identification. As much as these are survivors of the plant kingdom thriving in extreme conditions, they all have their geographical preferences. While some do well in the arid deserts, others thrive in cold alpine high altitude regions, and these differences are remarkable for identification. Others grow on trees that are found in wet and humid areas as epiphytes.

Geographical location can help you determine the type of a cactus, since they are native to certain areas and climates.

The current literature and studies have helped create this intensive simplistic list of characteristics that can help you tick the right boxes in your quest to identify the various cactus species. Cacti family is an excellent source of fascination and bewilderment for scientists, botanists and hobbyists alike. An even easier and practical way of reinforcing this knowledge is by making comparative characteristic analysis using familiar species. Working with what you know is a great way to learn even more. These incredible insights are bound to turn you into a great botanist, especially on matters cacti.

Last update on 2024-02-06 / Affiliate links / Images from Amazon Product Advertising API

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