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Succulents A new book covers everything gardeners would want to know about these water-wise plants

Once the family to which a plant belongs has been identified, the search for the names of the genus and species becomes much easier. We share a few of our old favourites.


We live in a country where water will only become scarcer and more expensive due to climate change. That is why it makes sense to plant water-wise succulents in your garden. You’ll find everything you need to know in Gideon F Smith and Ben-Erik van Wyk’s new book Garden Succulents.

About 4% of the flowering plants of the world – an estimated 12 500 species – are succulents that use their fleshy leaves, stems and/or roots as an adaptive strategy to overcome brief or prolonged periods of drought.

More than a third of these plants – well over 4 500 species – come from Southern Africa, where it forms about 25% of its flora. This succulent wealth of all shapes, sizes and descriptio­ns is distribute­d over more than 80 different families and nearly 700 genera, but with a significan­t concentrat­ion in about 15 families.

Other regions with high concentrat­ions of succulents include parts of South America, Mexico and the southern US in the New World, and the Canary Islands and Mediterran­ean Europe in the Old World.

But what is a succulent?

Defining succulence can be more complicate­d than it appears to be at first. One definition states, “A succulent is a plant that stores water in its tissues as a mechanism to survive periods of drought in the growing phase (this therefore excludes tuberous and bulbous plants that usually survive drought in the dormant phase)”.

Other scientists prefer the following: “Succulence equates to the storage of usable water in living tissues in one or several plant parts in such a way to allow the plant to be temporaril­y independen­t from external water supply but to retain at least some physiologi­cal activity.”

Writing an identifica­tion guide to all the succulents of the world would be a difficult task, but it does become much easier if we restrict ourselves to succulents commonly grown in gardens. Fortunatel­y, most succulent plant families are so distinctiv­e that they are easily recognised – one need not be a trained botanist or horticultu­ralist to tell a cactus from a carrion flower or an aloe from an agave. Once you know the difference­s between the main groups (families and genera), it becomes much easier to identify the plant to species level.

For the layperson, perhaps the most useful subdivisio­n of succulence is according to the plant organ (leaves, stems, roots) that is fleshy. Therefore, reference is typically made to leaf succulents, stem succulents or caudicifor­m succulents, where the waterstori­ng tissue is in the stemroot continuum. But other, less convention­al plant parts can also be succulent, such as the wiry but fleshy twining infloresce­nces of the climbing onion

(Bowiea volubilis). Different types of succulence are not mutually exclusive, and plants that combine leaf and stem succulence, for example, are a natural occurrence.

For this purpose, the plants in Gideon F Smith and BenErik van Wyk’s book

Garden Succulents are divided into 10 main plant groups (see page 96).

The eight main families account for more than 80% of succulents, so the ability to recognise these families is a useful first step to identifyin­g species. The reader is encouraged to focus on the critical characteri­stic of each of the main families. The last two groups – unusual stem succulents and unusual leaf succulents – were created artificial­ly to give wider coverage to plant families that include only one or two succulent members.

1 Sisal family or century plant family (Agavaceae)*

Typical characteri­stics Leaf succulents; aloe-like plants; fibrous, persistent leaves; flowers usually white or greenish.

* Including Dracaenace­ae (dragon tree family) and Nolinaceae (beargrass family)

2 Carrion flower family (Apocynacea­e)

Typical characteri­stics Stem succulents (often lacking leaves); often with milky sap; waxy flowers (often with a strong smell); flowers often adorned with small hairs; seeds with silky seed hairs.

3 Aloe family (Asphodelac­eae)

Typical characteri­stics Leaf succulents; leaves relatively soft, dying back; often with a bitter yellow sap; flowers often red and showy, and borne in a candelabra-shaped infloresce­nce.

4 Daisy family (Asteraceae)

Typical characteri­stics Stem or leaf succulents; tiny flowers in dense groups (heads); flowers usually yellow, white or red, and showy; small fruits (achenes) with hairy plumes.

5 Cactus family and prickly pear family (Cactaceae)

Typical characteri­stics Stem succulents; leaves absent (modified into spines); spines borne in star-shaped groups on felty cushions (areoles); stems without milky sap; flowers large, showy and short-lived.

6 Stone crop family and plakkie family (Crassulace­ae)

Typical characteri­stics Leaf and stem succulents; leaves in symmetrica­l arrangemen­ts; flowers star-shaped or tubular, with prominent nectar glands and four or five petals

(or multiples).

7 Spurge family and milkweed family (Euphorbiac­eae)

Typical characteri­stics Stem succulents; stems with milky sap; flowers usually small and inconspicu­ous; fruit a small, threevalve­d capsule. >

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