The families and the genera illustrated in this dictionary are described briefly in this chapter. Some reference books, most of which are monographic studies, that may be of use to interested readers are included in Further Reading. The most complete work on succulent plants is undoubtedly the three-volume A Handbook of Succulents Plants by H. Jacobsen, which covers most succulents in cultivation, although it does not include the most recent discoveries. Several periodicals specialize in succulent plants, and they are the best source of up-to-date information.
ACAVACEAE Endl. (MONOCOTYLEDONS) The Agavaceae family includes several plants of horticultural interest. It consists of about 18 genera, of which seven are illustrated in this book. The stems of the plants in this family are short or even absent. The leaves are usually arranged in rosettes, and they are long-lived, rigid and often have dentate margins. The roots are fibrous and stoloniferous. The flowers are arranged on tall inflorescences. The fruit is a capsule or a berry. Genera Illustrated Agave L.
This genus includes several species of use to humans. The leaves of Agave sisalana, for example, are a source of sisal, which is used for making ropes, sacking, insulation and so on. A. sisalana used to be cultivated in Sicily until 1940, but it was not economically viable, and now the remains of abandoned sisal orchards may be seen. Other species are used in Mexico to produce alcoholic beverages by fermenting the central part of the stem.
The leaves of agaves, which are very variable in size, are arranged in rosettes. The inflorescence is a tall spike -to 10 m or more - and usually has thick, modified leaves (bracts). The tubular flowers, which are borne in clusters, have six sepals. The fruit is a capsule with black seeds.
All agaves are monocarpic - i.e., the plant dies after flowering and seeding - but it takes several years for an inflorescence to be produced.
Distribution: America; a few species are naturalized in Mediterranean countries and tropical regions. Calibanus Rose A monotypic genus. Distribution: Mexico. Dasylirion Zucc.
There are approximately 18 species of simple-stemmed plants with long, lanceolate leaves with spiny margins. The inflorescence is branched, and the flowers are cam-panulate.
Distribution: Mexico and southern USA.
The 20 or so species are similar to agaves but have taller stems and longer leaves. The tall inflorescence is branched, and the flowers are campanulate. The fruits contain many black seeds. The plant dies after flowering. Distribution: Mexico. Nolina Michx.
There are about 20 species of small trees. Each plant has a succulent, swollen caudex covered with thick bark. The fibrous leaves are long and narrow. The tall inflorescence is branched and bears numerous small flowers. Distribution: Mexico to Guatemala. Sansevieria Thunb.
There are approximately 70 species of rhizomatous or stoloniferous plants with fibrous, succulent leaves. The elongated inflorescence is unbranched and is seldom produced in cultivation; the flowers are white or greenish. Several species are tolerant of shade and may be grown as house-plants.
Distribution: tropical Africa, India and Madagascar.
Between 40 and 50 species of small trees bear simple or branched stems. The leaves, which are arranged in rosettes, are flexible to rigid. The branched inflorescence bears nocturnal flowers. During the day the flowers do not close fully, giving refuge to the moths that pollinate them. The fruit is a dry or fleshy capsule with black seeds. Some species are hardy and can be cultivated outside the greenhouse if the cold season is not too long. Distribution: North America and West Indies.
AMARYLLIDACEAE J.St.Hil. (MONOCOTYLEDONS)
There are about 70 genera of bulbous plants, with corms or rhizomes. Only the genus Ammocharis Herb, is included
ANACARDIACEAE l.indl. (DICOTYLEDONS) About 70 genera of trees or shrubs with resinous bark are found in tropical and temperate regions of the northern hemisphere. The family contains several species of economic interest, including Mangifera indien (mango), Anacnrdium occidentale (cashew nut) and Pistacia Iciitiscus (pistachio nut).
Only the genera Pachycormus Coville and Operculycaria H. Perrier are considered succulent and are included in this dictionary.
APOCYNACEAE Juss. (DICOTYLEDONS)
The family contains about 215 genera of lactiferous herbs, lianas, shrubs and trees. The simple leaves have parallel veins. The flowers, which may be solitary or borne in clusters, have five petals and five sepals; the buds are contorted. The fruit is divided into two follicles. Several species are sources of pharmacological substances - alkaloids, glucosides and so on. The plants belonging to the three genera illustrated in this dictionary are very tender and need a warm position, and they require plenty of water during the growing season. Distribution: widespread. Genera Illustrated Adenium Roem. & Schult.
Succulent shrubs or trees with swollen caudices and lanceolate leaves, crowded at the stem apices. Distribution: tropical Africa, Arabian Peninsula and South Yemen (Socotra). Pachypodium Lindl.
Spiny trees or subterranean, caudiciform stems with caducous leaves.
Distribution: Angola, Madgascar, Namibia and South Plumeria L.
Shrub or trees with cylindrical stems and branches, lanceolate, dark reddish-green leaves and showy, fragrant flowers in various colours. Distribution: Mexico and tropical South America.
ASCLEPIADACEAE II. Br. (DICOTYLEDONS) The family contains over 2,800 species of lianas or low shrubs, some of which are succulent. The leaves are simple and caducous in most succulent species. The flowers have five sepals and five petals and are often malodorous. In the Stapeliae group pollen grains adhere together to form waxy pollinia (Fig. 1). The fruit is a follicle containing several seeds with a terminal tuft of hairs. The genera containing succulent plants have a complex and confusing taxonomy. The species with succulent stems are prone to rot if over-watered.
Distribution: tropical and temperate regions.
Fig. 1 A diagram of the flower of a plant in the Stapeliae group, based on Orbea. Pollen grains adhere together to form waxy pollinia.
Fig. 1 A diagram of the flower of a plant in the Stapeliae group, based on Orbea. Pollen grains adhere together to form waxy pollinia.
Plants have tuberous or fusiform roots with thin, caducous stems. Leaves are variable in shape. The flowers, which may be solitary or borne in clusters, have a round corolla and five lobes; the lobes may be free or united at the tips. Distribution: southern and tropical Africa. Caralluma R. Br.
Stoloniferous, clump-forming plants, with four- or five-angled stems bearing reduced, caducous leaves. The flowers are very variable in size and may be campanulate or have an open corolla; the corona has two whorls; the five outer lobes may be free or fused, and the five inner lobes are fused to the outer whorl. Distribution: Arabian Peninsula, north and eastern Africa, India, Mediterranean countries and South Yemen (Socotra).
These climbing or erect plants often have swollen tubers or fusiform roots. The calyx has five sepals, and the five petals of the corolla are united to form a tube, which is almost spherical at the base; the tips of the lobes are united to form a lantern-like structure (Fig. 2). Distribution: central and southern Africa, Canary Islands, India and Madeira.
Fig. 2 A side view of Hie schematic flower of Ceropegia. The corolla has five petals, which are united to form an almost spherical tube at the base while the tips of the lobes are united into a lantern-like structure. This type of flower can be pollinated only by specific pollinators, which are able to reach the pollinia down the long tube. Cynanchum L.
Climbing shrubs with fleshy branches. The corolla lobes of the small flowers form a pentagon. Distribution: central and southern Africa and Madagascar. Dischidia R. Br.
These are epiphytic plants with small, waxy leaves, some of which are modified into large, inflated pitchers inhabited by ants (see also Myrmecodia under Rubiaceae). The flowers are small. Distribution: Australia and India.
The four- to six-angled stems have spreading teeth. The leaves are small. The flowers, which appear on younger stems, are solitary or borne in clusters on stalks 1-3 cm long.
Distribution: eastern and western Africa. Echidnopsis Hook.f.
The stems have between 6 and 20 angles, the ribs being divided into hexagonal tubercles. Flowers are borne in clusters of two to four; they have no tube, triangular lobes and an inner whorl with five reflexed lobes. Distribution: tropical Africa, Arabian Peninsula and South Yemen (Socotra). Edithcolea N.E. Br.
The few species have five-angled stems to 30 cm high. Large, hemispherical flowers are borne at the stem apices. Distribution: Kenya, Somalia, South Yemen (Socotra) and Tanzania. Fockea Endl.
These caudiciform plants have tuberous roots and thin, twining branches. The flowers, which may be solitary or borne in clusters, are starfish-like.
Distribution: Angola, Namibia, South Africa and
A monotypic genus very similar to Caralluma but with persistent leaves to 6 cm long. Distribution: India. Hoodia Sweet
The many-angled stems, to 1 m tall, are covered with conical tubercles and hard teeth. Flowers, which are borne near the apex of stems, have a flat corolla, very small lobes and a five-lobed corona in two whorls. Distribution: Angola, Namibia and South Africa. Hoya R. Br.
These epiphytic plants have climbing stems and branches. The leaves are variable in shape and size, and in some species are thick and succulent. Inflorescences are borne in pendent clusters with several waxy, star-like and fragrant flowers.
Distribution: Asia, Australia and Polynesia. Huernia R. Br.
The short stems, which branch from the base, are four- to six-angled and have large teeth. Flowers are produced from the base of young stems and have a campanulate corolla.
Distribution: southern and eastern Africa, Arabian Peninsula and Ethiopia.
Notechidnopsis Lavranos & Bleck
Similar lo Echidnopsis but leafless at all stages of growth. Distribution: southern Africa. Orbea Haw.
The plants are similar to Stapelia and are often included in that genus.
Distribution: southern Africa. Orbeanthus L.C. Leach
The stems spread horizontally. The flowers are very showy and have a hairy corona. Distribution: southern Africa. Orbeopsis L.C. Leach
Flowers arc borne in clusters from the base of stems; the corolla is flat and there is no annulus. Distribution: southern Africa. Pachycymbhim L.C. Leach
Rhizomatous stems. The corolla may be campanulate or flat.
Distribution: southern Africa. Piaranthus R. Br.
The flowers arc small; the corolla is flat, and the tube is absent or campanulate; the lobes are lanceolatc. Distribution: southern Africa. Pseudolilhos P.R.O. Bally
The unbranched stems are stone-like. The inflorescence has many small flowers.
This genus is related to Caralluma.
Distribution: southern Africa.
A genus distinguished by its tuberous roots, climbing stems and loose pollinia. Distribution: eastern Africa. Rhytidocaulon P.R.O. Bally
The unbranched stems are papillose. Solitary flowers are borne on short stalks; the corolla has spreading lobes. Distribution: eastern Africa. Sarcostemma R. Br.
Thin-stemmed shrubs with clusters of flowers, with small, projecting corolla lobes. Distribution: tropical Africa. Stapelia L.
There are about 100 species. The flowers, which are borne on long stalks, have a five-lobed, usually flat, corolla; the deep lobes are triangular. The corona has two, five-lobed whorls, an inner and outer whorl.
Distribution: tropical and southern Africa.
This genus is closely related to Huernia.
Flowers with a long corolla are produced from the base of the stems.
Distribution: central and southern Africa. Trichocaulon N.E. Br.
Cylindrical stems are simple or branching from the base. The small flowers are borne between the tubercles towards the stem apices. The flat corolla has acute lobes. Distribution: southern Africa, Madagascar and Somalia. Tromotriche Haw.
A genus that is very similar to Stapelia and that was, in fact, formerly included in it. Distribution: southern Africa.
BASELLACEAE Moq. (DICOTYLEDONS) A family of about six genera of rhizomatous, climbing plants with simple, often succulent leaves. The branched inflorescence bears small flowers. Only one genus, Boussingaultia H.B. & K., is illustrated here. Distribution: tropical and subtropical America.
BO.MBACACEAK Kimth (DICOTYLEDONS)
There arc 30 genera of very large trees with soft wood. The leaves, which may be simple or compound, are covered with hairs or hairy scales. The flowers arc large. The two genera illustrated have woolly fruits with numerous seeds Distribution: tropical Africa and America. Genera Illustrated Bombax L.
These large trees often have spiny trunks and palmate leaves. The very large flowers appear before the leaves. Distribution: tropical regions. Chorisia H.B. & K.
The trees have swollen trunks that are usually spiny. The large flowers appear before the palmate leaves. Distribution: tropical America.
BROMEI.IACEAE Juss. (MONOCOTYLEDONS)
COMMEI.INACEAE K. Br. (MONOCOTYLEDONS)
The family contains about 50 genera of terrestrial or epiphytic plants. The basal leaves, which may have spiny margins, are often arranged in rosettes. Flowers are borne in spikes with coloured bracts. The epiphytic genera grow on the trunks and stems of trees. Distribution: tropical America. Genera Illustrated Abromeitiella Mez
Small, terrestrial rosettes form large clumps. The greenish flowers are usually solitary, and the petals are much longer than the sepals. Distribution: Argentina and Bolivia. Deuterochnia Mez
These short-stemmed plants have rosettes of leaves with spinose margins. Distribution: South America. Dyckia Schult.f.
The stemless rosettes have thick rhizomes. The leaves are rigid and have spinose margins. Distribution: South America. Hcchtia Klotzsch
Stemless or short-stemmed rosettes are formed from grey or red-brown leaves with spiny margins. Distribution: Mexico and southern USA. Puya Molina
The toothed and spinose leaves are arranged in rosettes, which may be stemless or long-stemmed, to 10 m tall when in flower.
Distribution: Argentina, Bolivia and Chile.
BL KSERACEAE Kuntli (DICOTYLEDONS) A family of about 20 genera of shrubs or large trees. The trunks, bark and wood are resinous. The leaves are compound.
These shrubs have caudiciform trunks and compound Distribution: Mexico and southern USA. Commiphora Jacq.
Shrubs with a very thick, tuberous caudex; similar to Bursera.
These tropical plants have jointed stems. The flowers are usually blue, a colour that is seldom seen among succulent
These plants, which have succulent leaves, are similar to Tradescanlia.
Distribution: Mexico, tropical South America and southeastern USA. Cyanotis D. Don
A genus of plants with tuberous roots and succulent Distribution: tropical Africa and Asia. Tradescanlia L.
These plants have fibrous or tuberous roots, jointed stems and leaves that are often covered with hairs. Distribution: North and South America.
COMPOSITAE Giseke (DICOTYLEDONS)
A very large family containing both annual and perennial plants, ranging from herbaceous plants to trees and including epiphytic and aquatic species. The inflorescence may bear from one to many heads of clustered, stalkless flowers, and the calyx has many bristles and scales
(pappus), which remain attached to the seeds and facilitate their dispersal by the wind.
These small shrubs have either entire or lobed leaves. They are winter growing and should be kept dry in summer. Distribution: Namibia and South Africa. Senecio L.
This very large genus contains several succulent species. The genus Kleinia has been included in this genus for the purposes of this dictionary. Distribution: widespread.
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