How to Identify a Succulent: Echeveria, Haworthia, Sedum and the Rest

Succulents are the worst labelled plants in the shop. They arrive in mixed trays marked "assorted succulent 5.5cm", and people assume that because they all store water they all want the same thing.

They do not. A haworthia scorches in the sun that an echeveria needs to keep its colour. A euphorbia looks like a cactus and bleeds an irritant sap that a real cactus does not have.

Here is how to sort a tray out.

Start with the shape from directly above

Photograph or look at the plant from straight above. Succulent identification runs on geometry more than colour, and colour changes dramatically with sun and season anyway.

• Tight symmetrical rosette, flat like a flower. Echeveria, sempervivum, graptopetalum.
• Rosette of stiff pointed leaves, often with white markings or a translucent window at the tip. Haworthia, gasteria.
• Leaves stacked along a trailing or upright stem. Sedum, crassula, senecio.
• Thick woody trunk with branches. Crassula ovata, the jade plant, or portulacaria.
• Ribbed column with spines from a cushion. A true cactus.
• Column or branch with spines but no cushion, and milky sap. Euphorbia. Not a cactus.

The distinctions that matter

1. Echeveria vs sempervivum. Look identical as rosettes. Echeveria leaves are thicker and often powdery, and it is not frost hardy. Sempervivum, the houseleek, is thinner leaved, often has fine hairs at the tips, survives snow outdoors, and produces offsets on runners.Can it live outside?
2. Haworthia vs aloe. Haworthia is small, usually under 15cm, with hard pointed leaves and often white ridges or windows. Aloe is larger with softer leaves that ooze gel when cut and have teeth along the margins.Does it ooze gel?
3. Cactus vs euphorbia. This is the important one. Cacti have areoles, small cushions from which spines grow, and clear sap. Euphorbias have spines straight from the stem with no cushion, and milky white sap that irritates skin and is genuinely dangerous in the eye.Check the sap
4. Jade plant vs portulacaria. Jade has thicker rounded leaves on a stout trunk. Portulacaria, elephant bush, has smaller leaves on reddish stems and grows much faster.Stem colour
5. String of pearls vs string of beads vs string of tears. All senecio. Pearls are spherical, beads are pointed at the ends, tears are teardrop shaped.Bead shape
6. Sedum morganianum vs echeveria. Burro's tail hangs in dense trailing ropes of plump leaves that drop at a touch, rather than forming a flat rosette.Does it trail?

Why it changes the care

Light. Echeveria, sedum and most cacti want several hours of direct sun and stretch badly without it. Haworthia and gasteria grow under other plants in the wild and scorch in full afternoon sun. Putting them on the same windowsill will fail one of them.

Water. Broadly similar, meaning soak then dry completely, but haworthia tolerates more frequent water than an echeveria and far more than a cactus.

Cold. Sempervivum survives frost and lives outdoors year round. Echeveria does not. They look nearly identical in a shop and one of them dies on a balcony in December.

Toxicity. Haworthia, echeveria, sedum and burro's tail are non toxic to pets. Euphorbias, kalanchoe, aloe and jade are not. If you have a cat, this is worth knowing before the tray goes on a windowsill.

What to photograph

From directly above, so the rosette geometry is clear. Then a side profile, which shows whether it forms a trunk, trails, or stays flat. Then a close shot of a leaf tip and margin, since teeth, windows, hairs and powder are the distinguishing features.

If it is flowering, photograph that too. Flower shape and how the flower stalk emerges separate several genera that look similar as foliage.

Do not rely on colour. Sun stress turns green echeverias pink, red and purple, and the same plant can look like two different species in summer and winter. Shape holds, colour does not.

One warning

Never break a spiny plant open to check the sap unless you are prepared for what comes out. Euphorbia latex is a serious eye irritant and can cause chemical burns and temporary blindness. If you suspect euphorbia, treat it as euphorbia and wear gloves when handling or repotting.

Photograph the plant from above and from the side and Identium will name the genus, tell you whether it is toxic to cats and dogs, and give you the light and watering it actually wants, which is the part that separates the survivors in a mixed tray from the casualties.