The North Surrey Branch

Of the British Cactus and Succulent Society

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Identifying succulents

To identify a plant you must firstly find out what Family it belongs to. Euphorbiaceae, Cactaceae, Liliaceae are some examples of succulent Families, more are detailed later. The next step is what genus does the plant belong to within the family. Within the Cactaceae family, there are a considerable number of Genera, each with their own characteristics. One such Genera is Opuntia. An opuntia has fleshy pads, jointed together to form the body. You see many of them growing all over the world where cold and damp conditions do not preclude them. The fruit of one species being known as a prickly pear. After identifying the genera, the most difficult part is to identify the species. For an opuntia, it might have distinctive pads, or spines.

To identify which family, Genus, species, your plant belongs to the factors are the flowers, body form, whether they have leaves, the type of sap, whether tendrils are present,  where they originally came from, and what type of spines they have. Just because a plant looks like a cactus does not in any guarantee that it is. There are many plant families that have plants that have a cactus like shape. Examine the plant photographs in this web site. The Euphorbiaceae family is a prime example, some of them look more like cacti than some cacti do themselves. Look at the photograph of the species Lophophora Williamsii, a cactus. It looks more like a mushroom than a Cactus.

If you cannot easily identify the plant from it's body form, then it is most likely that you will need to wait until the plant flowers. Flower structures are probably the most important way of identifying a plant. All cactus flowers have large numbers of petals, see the pictures on this site, so if your plant has a small number of petals, less than six say, it won't be a cactus. 

The Euphorbiaceae have very distinctive flowers, see the photograph below, and are almost exclusively small in size. The maximum size a Euphorbia flower reaches is around 0.5 cm with few exceptions, which is far too small to be confused with nearly all Cactus flowers. The shape and overall structure of Euphorbia flowers is very different to all other plants in that it is really a compound flower, known botanically as a Cyanthium. A typical Cyanthium consists of a Female central flower surrounded by a number of Male flowers. (Not always the case because there are Euphorbia species that have separate Male and Female plants)

If you seriously want to find out about, or identify succulents, one of the best books is written by a well known succulent lover and botanist Gordon Rowley. The book is called Name that Succulent, by Gordon D. Rowley and it's ISBN number is 0-85950-447-6.

A list of characteristics for the main succulent plant families

Crassulaceae :- There is a considerable number of succulent type plants in this family from small succulent leaved herbs to some that grow into small trees. (The money tree, Crassula Argentea, is probably the most well known representative) The one distinguishing factor for these plants is the flower structure. They have small star like or tubular structured flowers massed in corymbs. See the picture of an Echevaria on this site for some idea of what they look like or look at the flowers on the commonly found Sempervivums (Houseleeks). Their body structure varies enormously so it is often difficult to recognise them using body structure alone. A considerable number of them, Echevarias, Dudleya, Tacitus, Orostachys, have a typical star like leaf structure. Look again at the Echevaria to see what I mean. Others look like miniature trees with a Pachycaul like stem (Tylecodon)

I will publish more pictures of these plants on this site when I have more time.

Cucurbitaceae :- Yes, these are members of the Cucumber family. As such, it is the generally small yellow flowers that give them away and the typical fruits that follow them. They all have twining stems with tendrills to allow them to take advantage of tall plants in their vicinity. Some are defined as succulents because they have a large caudex. I have a Xerosicyos with a caudex some 30cms across.

Dideriaceae :- A small but unusual family of shrubs and trees. They have spiny trunks and branches with small and unisexual flowers. They are not plants for the beginner, and if you have one you are very likely to know what it is, otherwise you will loose it. High temperatures are required at the very minimum to keep them alive. They have thin grass like leaves when they are growing which immediately distinguishes them from Cacti.

Dioscoreaceae :- Climbing branches from a single tuber, having heart shaped leaves is the best way to describe them. Included among the species are the edible yams. One of the most well known species to Succulent growers is the Elephant's foot, otherwise known as Dioscorea Elephantipes. I will publish a picture of this plant when I have time.

Euphorbiaceae :- Flowers less than 1 cm wide, complex structure, colour usually yellow, can be white or red, mostly 2 petals. Photograph of typical flower below.

Fouquieriaceae:- Shrubs with prickly stem tending towards a Pachycaul structure. Comes from Mexico and SW USA. Has leaves that drop off when the plant has not had water for any length of time. The flowers have five petals joined together, but you are unlikely to see them in cultivation.

Geraniaceae :- See the picture of a Sarcocaulon for an idea of what the succulents in the family look like. Five Petalled and usually quite small flowers.

Gesneriaceae :- Only included here because of one plant, Rechsteineria Leucotricha. I have had one for years, you can't kill it off.  Tuberous plants with simple branches. An example of the flowers would be the structure of a Gloxinia. Mostly brightly coloured, with zygomorphic flowers a la Christmas Cactus.

Labiatae :- Only a few members are included as succulents. Succulent types of Coleus, and Plectranthus are grown by succulent collectors. Square stems, probably aromatic, ovary divided into four lobes are characteristics to look out for.

Lilliaceae :- The flowers are usually multiples born on racemes. Think of a tiger lilly with it's multiple flowers. The characteristic bell shape of the flower often gives away it's identity. Don't be fooled however, some of the flowers of the Lilly family are so small you might not notice this shape. Haworthia flowers are very small, but they are still members of this family.

Mesembryanthemaceae :- 1cm to 5 cm diameter, multi petalled like a cactus, all colours except blue, simple in structure. Photograph of typical flower below. Tend to have very fleshy leaves, and in their most extreme forms, tending to look like stones. See the Lithops plant in the plant list. Often low growing plants, but there are a considerable number of shrubby type plants.

Moraceae :- Mulberry or Fig family. Recognised by the greenish flat container of a number of bracts, the whole being the flower. Strange looking flowers, looking much like an outstretched hand on Dorstenias. Most succulent members have fat very fleshy stems, but some are small trees.

I have a number of these plants, and will include photographs of them at a later date. 

Oxalidaceae :- 

Recognisable by the long stalked , trifoliate, clover like leaves. There are a few succulent members having swollen stems, but not much else in the way of succulent characteristics.

Passifloraceae :- Only a few members of this family are claimed to succulents, they are in the Genus Adenia. They generally have conical, expanded trunks i.e. caudex like.

Pedaliaceae :-

A family that has it's 'roots' in Africa. In two genera, Pterodiscus and Sesamnothamnus large caudices (Swollen trunks) are developed. Colorful flowers are produced.

Peperomiaceae :-

Identified as in the well known Peperomia  house plants by the tall thin flower spike  that does not seem to have any flowers on it. These are microscopic and are to be found at the end of the flower spike, usually the part that is yellow.

Portulaceae :- 

All the plants of this family have succulent leaves. Portulaca afra is one of the most well known. The flowers are regular in shape, looking somewhat like sarcocaulon flowers, but having non matching numbers of Petals, sepals, and stamens. The usual structure is 2 green sepals, 4 to 18 petals, 1, 2 or more whorls of stamens. 

Vitaceae :-

The grape family. All succulent members have grape like fruits, but they are usually hard, and very small. The leaves have the typical structure of a grape vine. The succulents in this family are either caudiciform or pachycaul in structure i.e. they have a swollen base or trunk.

Some flower Pictures

Agavaceae :- The flowers are Trimerous (Three petalled) and usually in an abundance on a tall flower spike. Most of the plants are large, typical shape as in the photographs on this site. Typically, the leaves of Agaves have sharp spines at the tips. Other members of this family are Calibanus, Nolina, and Sansevieria. Calibanus can be recognised by it's large caudex body and long thin leaves. Sansevieria all look similar to the well known Mother in laws Tongue, a member of the Genus. Nolinas have a flask shaped trunk with long thin leaves protruding from it.
Agave Parasana		Agave Sp.
Anacardiaceae :- Contains the mango plant, Rhus, Sumach. Plants of this group collected by succulentophiles are pachycaul in structure (thick trunk)  Pachycormus Discolor
Apocynaceae :- Have five petalled flowers. In my experience, most plants belonging to the Apocynaceae family have very similar flowers, commonly yellow, white and the colour you see below. Pictured below is a free flowering clone of Adenium Obesum
Asclepiadaceae :- Again has pentamerous (Five Petal) flowers but has a large corona, typical lifebelt shape in the middle of the flower. See the picture of a Huernia for a typical flower. The body of the plant below is quite typical of a large number of plants in the Asclepiadaceae familiy, but there are slightly different forms that look more like Cacti. Huernia Macrocarpa
Bombaceae :- A small genus notable for it's Pachycaul members. Adansonia, Chorisia, and Cavanillesia are all members. Tree like, and with large flowers, you are not likely to come across them often although I have a Chorisia Speciosa grown from seed. This is recognised by it's spiny trunk. This plant grows outside all year at the south facing front of the house as in the photograph below taken in early January. Chorisia Speciosa
Burseraceae :-See the photograph of Commiphora Sp. for a typical member of this family. Commiphora Sp.
Cactaceae The flower on the left is fairly typical for a lot of plants in the Cactaceae family. Often very brightly coloured, and very thin petals that have an iridescent sheen to them. Some species, particularly Astrophytum Asterias in my opinion, have the most attractive golden sheen to them if looked at in full sun. I would assume that this is their way of avoiding overheating in desert areas by reflecting the light from their flower surfaces.  Some cactus flowers have a spiny Hypanthium (Flower stalk), others have smooth, or indeed hairy flower stalks.  Only one species of cactus comes from anywhere else except the Americas. There is suspicion that this was probably caused by birds carrying seeds.
Commelinaceae :- Flowers have three green sepals, and three coloured petals. The flowers are commonly blue which is rare in any other succulents. Tradescantia is the only genus of interest to succulent growers. I have no photographs at present of this family, but I am sure you will be aware of the housplants that belong to this family.
Convolvulaceae :- Ipomoea is the only genus of interest here. Underground caudex types are of main interest here. Creeping plants with attractive flowers (Beautiful blue), physically like the common convolvulus plant with white flowers found in U.K. hedgerows.
Euphorbiaceae Typical flowers of a Euphorbia. A large number of succulents are from this family, the Euphorbiaceae and some of them can be mistaken for cacti if they are not flowering. The flowers are produced in multiples from a common stem. The flowers are called Cyathiums and have two bracts (Petals). You can identify the bracts if you look at the disk like Cyathia.
Asclepiadaceae This particular plant  has evolved a body shape similar to some cacti. It's flower is very distinctive however, and indicates that it is a member of the Milkweed family. The five petal flower with its distinctive corona in the center of the flower is typical. A lot of variations occur in this family however, some flowers are tiny, millimeters in diameter, some are very large indeed. These plants as far as distribution is concerned are centered in Africa, but have spread through many tropical areas.
Mesembryanthemaceae Plants mainly from South Africa with a great diversity of shape. Some look like stones, their common name being living stones, others are shrubby in nature growing to several meters in height. The flowers of this family are however fairly uniform multi petalled types. Always a smooth tube to the flower unlike many cacti, and in general not much more in diameter than about 1.5 centimeters
	Lilliaceae Although the flowers may  be nowhere near the size of these flowers, the basic shape is that outlined in the black box. Nearly always, there are a number of flowers on what is called a raceme. You can just about make this out from the photograph. Occasionally, there is only one flower.  Haworthias have very many flowers per raceme, and the flowers are small and invariably white. There is still the characteristic bell shape.
Moraceae The flowers of this family are particularly  strange. See the hand shaped flower in the photograph to the right