Cactus Identification Chart: Types of Cacti by Shape

Check four things in order: whether the plant has areoles, its overall shape, its spines, and its flowers if it has any. Then match those features against the chart below, or photograph the plant and let an identification app suggest a name you can check against the same features.

• Areoles first. Look for the small cushions, often woolly, that the spines grow out of. Wikipedia describes areoles as structures unique to cacti, so this step tells you whether you are looking at a cactus at all.
• Shape second. Cactus Outlet's guide sorts cacti by growth form: columnar, globular or barrel, paddle-shaped, and branching or clumping. The shape narrows the list to a handful of groups.
• Spines third. Note the type (needle-like, hooked, feathery or hair-like), whether they spread out flat (radial) or stick straight out from the centre of the areole (central), and their colour.
• Flowers last. Flower colour and timing help separate close relatives, but many potted cacti rarely bloom, so do not wait for flowers.

Many spiny succulents are sold as cacti. Wikipedia notes that a number of spiny stem succulents are often assumed to be cacti when they are not. Four quick checks:

• Areoles. No areoles, no cactus.
• Milky sap. Debra Lee Baldwin's test: if it drips milky sap, it is a euphorbia, not a cactus. If you test this with a small nick, wear gloves and keep the sap away from your eyes.
• Leaves. Most cacti have no real leaves; Debra Lee Baldwin describes spines as vestigial leaves. The exception is Pereskia, which Wikipedia says keeps numerous leaves with a midrib and a flattened blade.
• Where it comes from. Wikipedia says cacti are native to the Americas, and only one species, Rhipsalis baccifera, also grows wild elsewhere, in tropical Africa, Madagascar and Sri Lanka. A spiny plant labelled as coming from anywhere else outside the Americas is very likely something else.

Match the overall shape first, then the details. Features are from Cactus Outlet (CO) and Debra Lee Baldwin (DLB).

1. Columnar: upright cylinders or trees

• Saguaro (Carnegiea gigantea). Ribbed column with sharp spines; large white flowers that open at night; up to 40 feet tall and slow-growing (CO).
• Mexican fence post (Pachycereus marginatus). Straight columns with vertical ridges (DLB).
• Peruvian apple cactus (Cereus repandus). Columns that branch like a tree (CO).
• Silver torch (Cleistocactus strausii). Slim columns covered in fuzzy silver spines (DLB).

2. Globular and barrel: balls and cushions

• Golden barrel (Echinocactus grusonii). Ribbed ball with golden-yellow spines; about 3 feet across when mature; small yellow summer flowers (CO).
• Golden pincushion (Mammillaria celsiana). A spiral pattern across the top (DLB).
• Thimble cactus (Mammillaria gracilis fragilis). Small, globular, clustering (DLB).
• Red-headed Irishman (Mammillaria spinosissima). Orange to red spines (DLB).
• Bishop's cap (Astrophytum myriostigma). No spines; smooth body dotted with fuzzy areoles (CO).
• Moon cactus (Gymnocalycium mihanovichii). Often grafted onto a green stem, in unusual bright colours (DLB).
• Domino cactus (Echinopsis subdenudata). White dots on the body (DLB).

3. Paddle and jointed: flat pads or segments

• Prickly pear (Opuntia species). Flat pads with glochids, tiny barbed spines that come off at a touch (CO; Wikipedia).
• Bunny ears (Opuntia microdasys). Flat pads with polka-dot tufts (DLB).
• Burbank spineless prickly pear (Opuntia ficus-indica). Pads bred without spines (CO).
• Teddy bear cholla (listed by DLB as Opuntia bigelovii). Dense, fuzzy-looking spines (DLB).
• Peanut cactus (Chamaelobivia 'Rose Quartz'). Short segmented stems with bright flowers (DLB).

4. Hairy: bodies hidden under hair or wool

• Old man cactus (Cephalocereus senilis). Long woolly hairs cover the stem (CO).
• Old lady cactus (Mammillaria hahniana). Fuzzy, hairy ball (DLB).
• Old man of the Andes (Oreocereus celsianus). Long white hair-like spines (DLB).

5. Trailing and forest cacti: hanging or flat stems

• Christmas cactus (Schlumbergera bridgesii). Trailing, segmented flat stems (DLB).
• Easter cactus (Hatiora rosea). Hanging habit, magenta flowers (DLB).
• Rat tail cactus (Disocactus flagelliformis). Thin, cylindrical trailing stems (DLB).
• Rhipsalis and other epiphytes. Wikipedia describes tropical forest cacti with flattened stems that grow on trees.

Once you know the group, spines separate the species. Cactus Outlet lists the features collectors use:

• Type. Needle-like, hooked, feathery or hair-like.
• Arrangement. Radial spines spread flat around the areole; central spines point outward from its middle. Count both.
• Colour and texture. Golden, white, red or translucent. Debra Lee Baldwin notes that translucent spines can make a whole plant glow when backlit.
• Pattern. On many globular cacti the areoles line up in spirals across the top, which Debra Lee Baldwin describes as a Fibonacci spiral.

Glochids deserve a warning of their own. Wikipedia describes them as short spines barbed along their length that are easily shed; they are why a prickly pear that looks soft is not. Handle pads with tongs or folded newspaper, not bare hands.

Yes. Plant identification apps, including PlantLens, suggest a name from a photo. A few habits make the answer more reliable:

• Take two photos. One of the whole plant to show its shape, and one close-up of an areole with its spines. Add the flower if it has one.
• Use daylight. Spine colour and hairs are hard to read under warm indoor light.
• Check the answer. Compare the suggested name against the features in the chart above. If the plant has no areoles or bleeds milky sap, the name should not be a cactus.
• Grafted plants. A moon cactus is two plants: a coloured top grafted onto a green stem (Debra Lee Baldwin). Photograph the top for its name.

For more on how photo identification works and how accurate it is, see our pages on finding the name of a plant and plant identification apps compared.

Desert cacti and forest cacti need opposite care. Debra Lee Baldwin says most cacti need full sun for most of the day and sparing water, and that their light and water needs differ from those of soft-leaved succulents, so they are best grown separately. Trailing forest cacti such as Christmas and Easter cactus come from a different habitat and are grown differently. Once you have a name, use our cactus plant care guide for desert types and our Christmas cactus care guide for the holiday cacti.

Research and drafting for this page were done with the help of AI, and every figure was then checked line by line against the sources listed at the end. Where sources disagree, we say so rather than pick one silently. If you find a mistake, tell us and we will correct it.