Succulents and cacti are unique plants in that they are explicitly designed with survival tactics in mind. Found in dry and often hot climates, these plants have adapted for efficient water retention, given their harsh environment. Their unusual structure and appearance have made them popular in many homes.
What Is the difference between succulents and cacti? Succulents comprise a broad category of plants that store water. Cacti are a family of plants within the larger succulent family, making all cacti forms of succulent. For a succulent to be considered a cactus, it needs to have an areole, which is specific only to cacti species.
Areoles and other specific characteristics help you to identify cacti from similar-looking succulent variations. Succulents are found in a wide variety of plant families, all with the ability to store water, bringing their similarities into view. In this article, we will break down the different types of succulents and cacti, so you know what to look for in spotting the differences.
Scientific Differences Between Succulents and Cacti
Let’s first examine the differences between succulents and cacti in their classification and scientific differences. This will help to explain how they are related to one another and what separates them.
A succulent is defined as any plant that has naturally adapted its structure to maximize the storage of water. They are characterized by thick tissue that can store water in their stems, leaves, or roots depending on the specific plant species. Cacti are a type of succulent that use their stems and branches for storing water.
Therefore, all cacti are succulents, but not all succulents are cacti.
Plant Taxonomy Classification Hierarchy for Succulents and Cacti
Plants are classified into hierarchal categories to organize and group related plants. This hierarchy starts with larger groupings and becomes more specific as plants are more similar to one another. Knowing how this classification works is essential to understand how succulents and cacti are related (as well as any other plants).
The general classification hierarchy for plants and organisms is:
- Kingdom: This category differentiates between different varieties of life, including animals, plants, fungi, bacteria, and other small organisms.
- Phylum/Division: Division is the more common term used in botany, and there are around four divisions in the plant kingdom. These divisions point to plants with ferns, conifers, flowers, and mosses.
- Class: This splits plants into groups of dicots and monocots. It differentiates between plants with two seed leaves and one seed leaf, respectively.
- Order: This classification further breaks down the different classes into more specific groups.
- Family: Plants that start to share many features are arranged into families. Usually, this is where groupings of plants are referred to with species of plants being placed into these categories.
- Genus: Within a family, specific plants are grouped that are more similar to each other than others.
- Species: This refers to the individual plant that is being examined. Typically, plants are written as genus and then species for their scientific classification. For example, a saguaro cactus is scientifically known as Carnegiea gigantea, with Carnegiea being the genus and gigantea being the species within the genus.
- Variety: Some plants may be further broken down into variety if there are minor differences within a species. This will be noted with ‘var’ and the variation name, but many species will not have variations.
In comparing succulents and cacti, we are going to go as far down as differences in family. Of the 452 plant families identified by botanists, over 50 families contain succulent plants. Not all families that contain succulents are entirely comprised of them, but all cacti are classified under the Cactaceae family. This specific family contains over 1,800 species of plants.
Some of the common plant families that include succulents are:
- Agavaceae/Asparagaceae: This family includes popular plants like Agave and Yucca.
- Aizoaceae: This family contains a significant number of succulent species, with nearly 2,000 different ones falling under this category. Popular plants include ice plant, Conophytum, Faucaria, and Lithops.
- Aloaceae: This family includes aloe, which has been further broken down for specificity into the Xanthorrhoeaceae family.
- Apocynaceae: Adenium and Pachypodium are among popular plants in this family. Periwinkle, milkweeds, and oleander also fall into this category.
- Bromeliaceae: Pineapples, Dyckia, and Spanish moss are popular plants in this family.
- Cactaceae: Other than the Aizoaceae family, Cactaceae make up the largest family of succulents. These are the families that contain plants with the definable areoles that separate cacti from other succulents.
- Crassulaceae: In this family, you’ll find jade plant and stonecrop, among other succulents. This family is responsible for the identification of unique photosynthesis processes that are specific to cacti and some succulent variations. This is known as CAM photosynthesis.
- Euphorbiaceae: Many plants in this family are not succulents, but the ones that are usually have leaf and stem succulents. They are one of the few succulent varieties that can be poisonous.
Succulent is a general term for plants that store water with cacti being a specific family of succulent plants. If you break down the classification hierarchy for cacti, it looks like this:
- Kingdom: Plantae (plants)
- Division: Magnoliophyta (flowering plants)
- Class: Magnoliopsida (two seed leaves, larger flowers)
- Order: Caryophyllales (includes many succulent plants)
- Family: Cactaceae (Cactus family)
- Genus: Will vary by specific plant
- Species: Most specific to individual cactus plants
- Variety: Must be looked at on an individual cacti species basis
Noting the scientific differences in taxonomy and classification helps botanists and gardeners to understand how the plants they work with are organized better as well as similar behaviors for growth patterns and care.
Structural and Visual Differences Between Succulents and Cacti
Looking at the specific structure and characteristics of a cactus makes it easier to know what to look for in comparing them to a broader range of succulents. Cacti separate themselves from other succulent families and species in specific ways. Remember, all cacti are considered succulents, but some succulents are not related to cacti.
The most significant difference that separates a cactus from any other succulent or plant is the presence of areoles. These are spots on a cactus that hair, spines, bristles, and spikes come out of. These may vary in their appearance, including size, color, and shape. Some species may grow new branches from these areas, but they are most similar to the creation of a bud.
Areoles are specific to cacti, so you can easily spot the difference between this family and other succulent plants. Because there are so many species of cacti, areoles are one of the only characteristics that remain consistent across the family of plants.
Other characteristics that are common among this family (but not all) include:
- Stem succulents: Most water is stored in the stems of the cacti as there is often most space and mass for water retention.
- No leaves: Cacti do not have leaves – they have spines instead.
- Dormant in winter: To protect themselves from low desert temperatures, cacti remain dormant during wintertime and will continue to grow in the summer.
- Spiny protection: The spikes that protrude from the areoles are designed as a defense mechanism against animals and predators.
- Flower producing: All cacti will produce some form of flower, as they are classified under the Magnoliophyta division of plants.
Many other succulent species may also contain similar characteristics to cacti but will not contain areoles. The only similarity among all succulents is their ability to store water. There is significant variation between various succulent plants, with cacti typically being distinguished and separated due to the different characteristics and sheer number of variations to study.
While cacti typically store water in their stems, other succulents use their leaves (no leaves for cacti) and roots for water storage as well. Most succulents do contain leaves, with many of them being oriented in unique and mesmerizing patterns. These leaves are often thick to retain water. Additionally, not all succulents are flowering plants, unlike cacti, and they don’t typically have spikes.
Differences in Care and Survival for Succulents and Cacti
The survival and growth of succulents and cacti vary widely as different species are native to varying environments. These plants have adapted to maximize their chances of survival, whether it is related to climate, nutrients, or protection from their surroundings.
There are five primary categories where succulents and cacti draw both similarities and differences:
- Water demands and care
- Light requirements and photosynthesis methods
- Weather variations and needs
- Protection from predators
- Propagation methods and techniques
Understanding these requirements and needs for survival not only compares succulents to cacti, but it also allows for more effective care techniques and approaches.
Water Demands for Succulents and Cacti
Succulents and cacti are more similar than they are different in terms of plant care as they are both designed for survival. Specific species of both may have different care routines, but for the most part, they need to be cared for in similar ways. In terms of watering, these plants do not do well in wet environments or if they are overwatered.
All succulents are designed to take advantage of environments where little water is provided, making sparse watering necessary. For at-home care, it is recommended that these plants are only watered once a week and with ample drainage. This is a fairly regular schedule for these plants to be best suited for growth, especially during the summer months.
Cacti and succulents also need lots of water when they are watered. This means that they need to be drenched to absorb enough water to fill their stems (cacti) or leaves and roots (succulents). This will leave them with a plump or bloated appearance as they fill with water.
In the winter months, watering should occur far less frequently due to dormancy. Almost all cacti and some succulent species will become dormant in the wintertime. Specific succulents will not become dormant, creating another difference between cacti and succulents.
Light Requirements and Use for Succulents and Cacti
All succulents need sufficient light to survive. Some succulent varieties, including the cacti family, have adapted their photosynthesis process to account for arid climate conditions. Many desert succulents use CAM photosynthesis or crassulacean acid metabolism photosynthesis. It was named for the succulent family that this method was discovered.
Stomata (holes in leaves) in all plants will open to complete photosynthesis by collecting carbon dioxide. In CAM photosynthesis, this opening only occurs at nighttime during cooler temperatures so that the cacti do not lose moisture they need to maintain. They hold the carbon dioxide until the daytime when the process is completed with sunlight.
Some, but not all succulents, will use this CAM photosynthesis process to best adapt to their natural environments. Pineapple is another common succulent that uses this process. This is another difference that distinguishes between cacti and many succulent species.
While succulents and cacti do not need much water to survive, they do need lots of sunlight. Most species of both will require full sun to thrive, with cacti generally requiring more sun than other succulent varieties. For succulents, sunlight often impacts their ability to maintain vibrant colors, with limited sunlight keeping them green.
Weather Variations and Needs for Succulents and Cacti
While both designed for water retention, the environments that succulents and cacti grow in can be quite different. Cacti and other desert succulents are quite similar in the tolerance to hot and dry weather conditions, while other succulents are native to tropical environments with more temperate climates.
Cacti can withstand more considerable temperature changes than many succulent species as deserts get very hot in the summer and very cold in the winter. This helps to explain why they practice dormancy in the winter months when temperatures drop significantly. Many succulents cannot survive these massive temperature fluctuations.
Most succulents and cacti thrive in warm environments, between 65 and 90 degrees Fahrenheit, with specific variations adapting to temperatures that fall above and below. Most cacti do not do well in humid environments, while some succulents, especially tropical variations, are more welcoming and tolerant of these wetter conditions.
To compare the two, cacti are typically far more tolerant of extreme weather conditions than most common succulent species. This hardiness is due to their native environments, which are typically desert-based compared to succulents, which can be found in many conditions. While they may have limited access to water, succulents are found all over the world in high and low climates.
Protection from Predators for Succulents and Cacti
Many plants grow or adapt in structure to protect themselves from predators. Especially in desert climates, succulents are susceptible to being eaten as they often contain water and can be nourishing to many animals. To avoid this, many plants have developed rigid or harmful defense mechanisms to keep animals away.
Cacti are most famous for this protection as they often contain a variety of spines and sharp, spiky features. Growing from the areoles, these structures can be dangerous and injure those who try to touch or eat them. A vast majority of succulent varieties do not contain these spikes, making them much easier to uproot and eat if needed.
Cacti separate themselves from most succulents in their threatening appearance and ability to ward off predators. If you have touched many common succulents, you’ll find that they are quite soft to the touch. These make it easy for animals to eat them. Plants such as aloe and agave contain sharp edges on their leaves for similar defense purposes.
Beyond physical structure, their chemical composition is also used for protection. The majority of cacti species are not poisonous, relying on the anatomical structure for defense. Conversely, some succulents are deemed poisonous, especially for animals.
These are some common succulent species that may be harmful to humans or animals:
- Aloe vera: While it can be ingested or used topically (and often is by humans) for antioxidants and burn relief, aloe is toxic for dogs, cats, and horses.
- Euphorbia family: This family of plants is toxic to both humans and animals. The sap found in them can be irritating to your skin. This same reaction can occur internally if ingested.
- Jade: This is a common succulent variety, and it is toxic to animals. There are different variations of jade plants, and all should be avoided by animals.
- Kalanchoes: These succulents are not dangerous to humans but can make animals sick if ingested. They are characterized by small pink or red flowers arranged in clusters.
The most danger arises from their structural spikes and injuries that may occur from physical contact. This is more of a concern with cacti than succulents as they are not usually as spiky.
Propagation (Breeding) Requirements for Succulents and Cacti
Propagation is the process of reproducing or breeding a plant by taking a portion of the plant from its parent. This can be completed with sexual reproduction, requiring pollen and egg to join for seed creation. This occurs in the floral sections of a plant. Asexual reproduction uses roots, stems, or leaves to create identical offspring from one parent plant.
Succulents and cacti propagate quickly, which is another survival strategy for various species. This is not only important in nature, but if you are interested in growing these plants, it makes it a simple process to do at home. Succulents are generally reproduced by separating them from the root of the plant, while cacti can be propagated by removing individual heads.
The method of cutting succulents and cacti for propagation engages in asexual reproduction. Because not all succulents are flowering, this method is taken advantage of most frequently. Because all cacti are flowering plants and not all contain structures for cutting, cacti can reproduce through both sexual and asexual reproduction. Stem cutting is often the easiest.
You may find that leaves or structures of both succulents and cacti that naturally fall have formed into a new plant. This is a survival mechanism, especially if the plant has been damaged or tampered with. Its fallen component can grow into a new plant and continue the survival of the species.
Different Types of Succulents and Cacti
There are thousands of species of both succulents and cacti, offering an extensive range of plants that vary in conditions for growth as well as physical appearance. We wanted to point out some of the most common variations in succulents and cacti and the key characteristics that separate them from one another.
While cacti are considered succulents, they are generally not included among popular succulent species because they have such specific characteristics and thousands of species within their own family. We will break them down into two separate categories for clarity.
The most common and popular succulent varieties include:
- Aloe vera: One of the most popular succulents for their historical healing qualities, they are characterized by long and thick leaves that branch out from one stem. Aloe is often covered in small serrations as protection.
- Zebra plant: Scientifically known as Haworthia, they are white and green with a pattern similar to a zebra. They have pointy leaves and will bloom small flowers.
- Snake plant: Also known as Sansevieria trifasciata, they have tall and upright leaves, giving them a unique look compared to other succulent varieties. The leaves have unique streak patterns and will thrive in low-light environments.
- Echeveria: One of the most popular succulent varieties for their rose-like configuration, this genus is found in the Crassulaceae family. They come in a beautiful range of colors and have commercially become most recognizable among all succulents.
- Agave: Native to Mexico and the southwestern United States, multiple species fall under this genus. Many agaves are spiked for protection, and some species are edible. Flowers, stalks, and the sap are used to make many edible products, including syrups and nectars.
- Stonecrop: Sedum is a popular succulent that is often used as a groundcover in garden applications. They come in many varieties, often with small spiky leaves and will produce flowers.
- Jade: Scientifically known as Crassula ovata, they are characterized by thick branches with hearty but small leaves. ‘Jade’ points to their green coloring, but this can vary based on the plant.
- Hens and chicks: Also known as Sempervivum, these are also rose-like in appearance. Their leaves are typically more pointed and spikier than Echeveria.
All of these plants are designed to thrive in low-water environments are typically characterized by having waxy or glossy looking surfaces to retain moisture best.
When filled with water, the leaves, roots, or stems will appear swollen or expand to accommodate more water in their tissues.
Cacti also come in a variety of species (over 1,800!), and most of them are found in the Western Hemisphere. Because there are so many, we have broken them down by their growth shape and appearance, with specific species mentioned in each.
These are general categories for different types of cacti:
- Tree-like: Your larger cacti typically fall into this category, including saguaro (Carnegiea gigantea) with a long stem and tall branches. This is one of the most popular visual representations of large cacti in the desert. Pereskia is a rarer genus that looks like tropical trees, with bark that does not often resemble most cacti.
- Columnar: Tall and shaped like a column, these cacti are usually single tubes and are put into the Cereus genus due to their elongated bodies. These include organ pipe cacti (Stenocereus thurberi) and hedgehog cactus (Echinocereus).
- Globular: As their name suggests, these small cacti are shaped like little globes or balls. Some common types include golden barrel (Echinocactus grusonii) and moon cactus (Gymnocalycium mihanovichii).
- Bush-like: These often grow in a cluster-formation with various branches and pads growing from stems. Popular variations include prickly pear (Opuntia) and Christmas cactus (Schlumbergera),
The broad species variety has made both succulents and cacti popular because they appear in very unique and beautiful appearances. For home growth, they are both easy to care for and low maintenance due to their limited watering requirements and ability to grow in a wide variety of environments.
Succulents vs. Cacti
This article has demonstrated that succulents and cacti have specific differences but draw many similarities as all cacti fall under the broad category of succulent plants. With areoles being there one key distinguisher, physical appearance is often the best way to determine the difference between the two upon visual inspection.
Cacti tend to be much more resilient plants as they are often found in more arid and challenging climate environments, such as the desert. Many succulents cannot withstand the intense temperature fluctuations that cacti experience in their native environments. Natural environments for species determine the conditions in which they can best thrive.
Whether you plan to grow them at home or merely appreciate them in nature, their unique adaptations for survival have resulted in long-lasting and exciting looking plants that are appreciated by scientists and gardeners alike. While all cacti are succulents for their water-storing abilities, not all succulents are cacti, and they definitely stand out!