Aloe Linnaeus (1753)
Greek: alsos, Arabic: alloeh = bitter
Over 450 species of Aloe have been described with diverse forms and sizes. The genus includes small grass-like herbs and stemless succulent rosettes a few inches tall to larger species with stout 60ft trunks, occupying the ecological niche of trees. Aloes, with their waxy leaves, are well-adapted to harsh climates with infrequent precipitation. They can flower many times with clusters of yellow, orange or red tubular flowers, angled downwards on a simple or branched inflorescence.
Aloes are distributed across sub-Saharan Africa, Madagascar, and Arabia. Aloes feature in prehistoric rock art by bushmen, and have been cultivated for thousands of years. Although Aloes are mentioned in the Bible, this probably refers to another resinous plant. However, the Egyptian Ebers Papyrus (ca. 1552 BC) refers to the medicinal value of Aloes, which were also used in embalming. Aloes were known to the Greeks by 400 BC. The Greek herbal of Dioscorides (41-68 AD) recommends Aloe applied externally for wounds, hemorrhoids, ulcers and hair loss, and internally as a laxative.
Aloe vera became so widely grown as a medicinal plant in ancient times that its exact region of origin is a mystery. This species is of considerable economic importance and extracts are included in all manner of pharmaceutical preparations for the skin, treatment of burns and for ingestion. It is important to use the correct species of Aloe for medicinal preparations, as some species e.g. Aloe venenosa are poisonous. Toxic reactions by sensitive individuals to Aloe barbadensis (Aloe vera) have been reported, despite its widespread, mainly safe use.
Aloe ferox and other species are cultivated for the bitter properties of their sap (bitter Aloes) which discourages predators. Aloe vera & Aloe ferox are the basis of a sustainable £multi-million industry in South Africa.
Cultivation: Partial to full sun suits most species of Aloe. The larger Aloes enjoy more direct sunlight than the smaller species as they would normally grow through and above protective vegetation. However, strong sunlight may be needed to develop the attractively bronzed foliage that some species develop in their habitat. Many Aloes produce spectacular racemes of packed tubular yellow, orange or red flowers and are of considerable horticultural merit for the tropical garden or larger glasshouse. Numerous small species can be grown and will produce their showy flowers on a sunny window ledge. Aloes may be grown from seed but hybridise freely between species in flower at the same time. Some inter-specific Aloe hybrids are available as well as Aloe x Gasteria hybrids.
Watering regimes should reflect whether the plant is from a summer or winter rainfall area. Some species can be remarkably sensitive to water at the wrong time of year while they are resting. Although most species tolerate cool dry winter conditions, few species are sufficiently hardy to withstand cold wet winter weather in the UK and similar climates.
Notable exceptions include the near-alpines, Aloe aristata, Aloe polyphylla and Aloe striatula. My hardy Aloes are potted up in frost-resistant clay pots with plenty of crocking. A potting mixture containing around half to two-thirds granite chippings added to my usual free-draining cactus mix is suitable for hardy succulents kept outside and not dissimilar to the way one sees plants growing in their habitat.
|
 |
Aloe arborescens Syn: A. mutabilis (Krantz Aloe, Kransaalwyn) from South Africa, a medium-sized shrubby, branching Aloe growing to 6 ft, with large, decorative spikes of yellow, orange or red tubular flowers. Bicoloured forms are also known. More than one of the unbranched inflorescences can be produced from each rosette. In strong light the bluntly-toothed leaves take on a grey-green colour.
Aloe arborescens is widely distributed through the Eastern Summer rainfall regions of South Africa, Mozambique, Malawi and Zimbabwe and grows from sea level to the tops of mountains, often growing on exposed rocky ridges (= krantz). It is widely-cultivated in tropical countries, as a garden ornamental plant, for hedging and for the healing properties of its leaves. Propagation is easy from stem cuttings.
|
|
Aloe aristata (Torch Aloe) from South Africa forms a small stemless 6-8 in rosette. The triangular soft green leaves have raised white spots, especially on their undersides, finely toothed edges and filamentous tips. The rosettes offset freely and with time will form a substantial clump. Offsets may be removed and used for propagation.
Aloe aristata is often grown indoors as a window-ledge plant, but it is very hardy. In the Drakensberg mountains it grows at up to 7500 ft and is equally happy growing outside through the wet English winter, provided that it is potted up in a very free-draining medium. It does well on a sunny patio, potted up in almost pure granite chippings mixed with a small amount of soil. During the summer it flowers freely, with 10 in spikes of tubular pink flowers attracting bees and other insects.
|
 |
 |
Aloe bellatula is a choice, tender plant from Madagascar, growing at elevations of around 4500 ft. The long (10 in ) thin leaves are marbled brown and green, becoming bronzed in strong light. Tiny, pale teeth along the leaf margins make them feel rough rather than sharp. The rosettes offset freely at their base to form a dense clump. The inflorescence consists of a raceme of delicate pink and darker pink striped bells on the end of a long stalk.
This plant is easy to grow on a sunny window-ledge. In England it flowers freely in mid-December.
|
| |
|
Aloe albiflora is very similar to Aloe bellatula but with pure white flowers. |
 |
 |
Aloe ciliaris (Climbing Aloe) is a small, fast-growing species from the Eastern Cape of South Africa, capable of scrambling up to 30 ft through scrub or along the ground. The recurved dark-green leaves are well-spaced along the upper part of the stems, bear tiny marginal teeth and may have white spots on their surface. The margins of the leaf-sheaths around the stems bear distinctive white hair-like teeth (hence ciliaris). The decorative racemes of tubular orange flowers are sunbird pollinated.
The Eastern Cape has a hot dry climate with mainly summer rainfall, a guide to watering this plant. This species is often used for landscaping in frost free climates and flowers throughout the year.
|
|
Aloe deltoideodonta var. candicans is a medium-sized plant, growing at 2000 - 2500 ft in the mountains of central-southern Madagascar. The stemless rosettes of triangular pale green leaves (up to 6 in long) with prominent longitudinal darker green lines and finely toothed margins, spread by offsetting from the base to form loose clusters. The inflorescence bears a cluster of salmon-pink tubular flowers.
Left: Desert Botanical Garden, Phoenix, Az., Sept. 2004.
Aloe deltoideodonta var. deltoideodonta - darker green leaves with variable amounts of broken white lines or spots.
Aloe deltoideodonta var. brevifolia as var. deltoideodonta but rather shorter more triangular leaves.
|
More pictures of Aloe dichotoma
|
Aloe dichotoma is a distinctive tree Aloe from dry rocky areas of the Western Cape and Namibia. The common name refers to the traditional use of hollowed stems of this tree as quivers. This is one of the largest species of Aloe, growing up to 30 ft tall.
A single trunk divides into numerous branches at the top, each branch bearing a rosette of narrow grey-green leaves. Old leaves are not retained on the smooth, but ridged trunk with sharp edges to each scale. The inflorescence is divided into three to five racemes of large tubular yellow flowers.
In a young plant the leaves are arranged in vertical rows and only with maturity, spiral to form a rosette.
Left: North Escarpment near Nieuwoudtville, RSA. December 1998.
|
|
Aloe dorotheae is an attractive medium-growing species from Tanzania. The rosettes are bright green in average light but develop a coppery-red hue in full sun. The shiny leaf surface is marked with scattered white spots and the leaf margins have prominent teeth. The rosettes offset freely by suckering to form dense clumps. The unbranched inflorescence carries clusters of glossy bright red tubular flowers. This is an attractive ground-cover plant for frost-free xeriscaping.
Left: Desert Botanical Garden, Phoenix, Az., Sept. 2004. |
|
Aloe excelsa (Noble Aloe) from Zimbabawe, Zambia, South Africa and Mozambique is a tree Aloe with a solitary stem up to 14 ft, bearing a large rosette of 3ft dark green sword-shaped leaves with reddish-brown marginal teeth. The leaf surfaces are thorny, especially those of younger plants. Old leaves remain attached to the stem, providing protective felting. The branched candelabra-like inflorescence carries 10 - 15 racemes of orange to crimson flowers.
Aloe excelsa is an impressive plant, widely used in landscaping. It grows at up to 2500 - 5000 ft and receives mainly Summer rainfall and a cool, dry Winter. Traditional use is made of antimicrobial substances in the leaves and as a treatment for a variety of digestive disorders and diabetes.
|
 |
Aloe falcata (Vans Rhynsdorp Aloe) growing near Vans Rhynsdorp, South Africa, December 1998. The smooth blue-green leaves have sharp brownish teeth along their margins and form compact rosettes which often lie at an angle. Aloe falcata flowers in December - January, mid summer in the Southern hemisphere and the hottest time of the year. The branched inflorescence carries spikes of tubular orange flowers.
This species comes from a winter rainfall area in the North-Western Cape and should be watered carefully and hardly at all during the summer flowering season when it would usually be completely dry. It requires water during the winter which may be a problem in cool climates.
|
More pictures of Aloe ferox |
Aloe ferox (Cape Aloe, Bitter Aloe, Bitteraalwyn, Bergaalwyn) is a tall, single stemmed Aloe up to 10 ft tall with a wide distribution in the South African Cape, Southern KwaZulu-Natal, Lesotho and the Free State, in grassland and bush in both Summer and Winter rainfall areas.
The large 3ft, tapering, fleshy, grey-green leaves with reddish-brown toothed margins are arranged in a dense rosette. Teeth may be present on the leaf surfaces, especially in immature plants. Old leaves remain as protective felting on the stem, leading to a rather untidy appearance.
Left: Aloe ferox flowering at the Kokerboomkwekery, Van Rhynsdorp. Xmas 1998
|
The flowers in various shades of orange are carried well above the leaves on candelabra-like heads with up to ten dense flower spikes. Copious production of nectar makes the flowers attractive to birds, insects and monkeys.
Aloe ferox is an impressive feature plant for a Mediterranean climate, or as a container plant if it can be given Winter protection. However it is grown, it needs full sun and free-draining soil to prosper. This species hybridizes freely with other Aloes.
Aloe ferox is the source of "Bitter Aloes," the yellow juice from just under the skin, which is a powerful purgative. The gel within the middle of the leaves has similar soothing properties to that of A. vera.
|
 |
Aloe juvenna from Kenya has small rosettes of triangular green leaves bearing white spots, some raised, or streaks and prominent inward-curving marginal teeth. The rosettes turn reddish-brown in full sun. Old leaves remain green, so as the stem elongates a characteristic densely-stacked rosette forms. Stems offset at their base or occasionally higher up to form a dense clump. The unbranched inflorescence carries a cluster of tubular red flowers.
A tolerant plant for any window-ledge, but dislikes being watered during its winter resting period. Often confused with Aloe squarrosa.
Photo: Jim Myers
|
|
Aloe microstigma is widely distributed across the dry interior of the Western to Eastern Cape Province. The medium-sized blue-green rosettes turn bronze and curl inwards in full sun or when stressed, thus protecting the inner rosette. The leaves are speckled with white spots and their margins have prominent brown teeth.
This species flowers freely through the winter with dense spikes of tubular orange flowers turning yellow as they open. The nectar from these is attractive to birds which are the main pollinators. A suitable plant for frost-free dry gardens.
|
 |
 |
Aloe peckii grows on gypsum soils in Somalia at elevations of around 5000 ft. The stemless olive-green rosettes have fleshy, usually streaked or banded leaves (6 in) whose margins bear sharp brown teeth. The branched inflorescence has spikes of small straw-coloured to greenish-yellow flowers, with paler petal borders
causing a striped appearance.
The flowers distinguish this species from the similar A. somaliensis which has pink to red flowers.
Left: Desert Botanical Garden, Phoenix, Az., Sept. 2004.
|
|
Aloe pendens from the Yemen has a lax speading habit making it suitable as a ground-cover or hanging-basket plant. In its habitat it grows down rock faces.
The narrow floppy leaves have small white spots and toothed edges. The stems offset freely at their base. The thin flower stalk bends down and then upwards to display a spike of yellow or orange-red tubular flowers. Flowers are produced throughout the year.
|
|
Aloe plicatilis (Fan Aloe) has a limited distribution in the mountains of the South-Western Cape, a winter rainfall area. This distinctive Aloe is is popular with collectors, although it is slow-growing and in a temperate climate is sensitive to watering. Large specimens may grow up to 15 ft tall.
The grey-brown stems are forked with clusters of strap-shaped blue-green leaves arranged in two opposite rows on the end of each stem fork. The 10 in leaves have a few small teeth distal to the stem. The fan-shaped arrangement of leaves is unique to this species. Each leaf cluster can produce a single cylindrical raceme of tubular scarlet flowers towards the end of the winter.
Left: Kirstenbosch Botanic Garden, RSA. December 1998.
|
Photo: Mike Kaplan
|
Aloe polyphylla (Spiral Aloe, Kroonaalwyn) grows at 6000-8000 ft in the Drakensberg mountains, where it sometimes experiences winter snow. Even during the summer, rain is frequent. This is one of the few Aloes that will withstand the constant wet, frost and snow of the English winter, provided that it is growing in very free-draining soil. It is more likely to suffer during over-hot summers. In it's habitat, Aloe polyphylla grows among loose basalt rocks and in rock crevices so potting it up in a medium containing a high proportion of granite chippings is not inappropriate for a damp climate.
In a mature Aloe polyphylla over 8 in and up to 18 in in diameter, the grey-green leaves are ranked as five rows in a spiral, which may be either left or right-handed. The leaf magins carry a few small teeth. The sharp leaf tips, tend to go brown.
|
The plants are stemless and do not offset, so propagation must be from seed. The branched inflorescence carries clusters of reddish tubular flowers which are self-sterile and cross-pollinated in their habitat by sunbirds. This species is listed as endangered, partly due to collection. However, plants grown from seed or from micro-propagation are becoming freely available and do well in cultivation.
|
|
Aloe pseudorubroviolaceae (Arabian Aloe) forms clumps of large 2 ft diameter rosettes of smooth, thick, blue-grey leaves with toothed margins. In very strong light or when stressed by drought, the leaves may take on a pinkish hue (hence pseudorubroviolaceae). The branched inflorescence of waxy orange-red tubular flowers is produced in winter.
This plant grows on steep slopes above 6000 ft in Yemen and Saudi-Arabia and is reported as tolerating light frost providing that it is grown in full sun in very well-drained soil.
|
 |
Aloe reynoldsii from the Eastern Cape of South Africa is a low-growing rosetted plant, clumping with maturity. The waxy, blue-gray leaves have longitudinal striations, white spots and marginal fine white teeth. The inflorecence is a panicle of bright yellow to orange flowers. This species was named for the plant collector Gilbert W. Reynolds.
Aloe striata is a similar plant except that the leaves are unspotted with more conspicuous longitudinal striations
and the inflorescence is a panicle of coral-red flowers.
|
 |
Aloe secundiflora is a medium-sized solitary stemless Aloe from Kenyan and Tanzania. The curved stiff, shiny leaves (20 in) have margins with sharp teeth. There may be a few white spots on the leaf surface, especially before maturity. The branched inflorescence has racemes of well spaced, small red tubular flowers with paler to yellow mouths.
Aloe secundiflora is drought tolerant but not hardy. Extracts of the plant may have useful antimicrobial properties and as a substitute for Aloe vera.
Left: Desert Botanical Garden, Phoenix, Az., Sept. 2004.
|
 |
 |
Aloe speciosa (Tilt-Head Aloe, Spaansaalwyn)
(Latin: speciosa = showy)
is a medium-sized tree Aloe up to 20 ft with an untidy rosette of long tapering blue-green leaves, on top of a stem that is often felted with old leaves. Leaf margins are furnished with small reddish teeth. The terminal rosette often tilts towards the North in its habitat i.e. facing the sun, but towards the maximum light elsewhere. The inflorescence is a dense cone-shaped spike of flowers, often with multiple spikes from one rosette. The flower buds start off deep pink, maturing to a greenish-white. As the flowers open, the orange to brown stamens and style are exerted and provide most of the flower colour.
|
Aloe speciosa is widely distributed from the Western to Eastern Cape of South Africa in hot, dry river valleys and low mountain slopes. It experiences both Winter and Summer rainfall, with the latter predominating. This is a spectacular plant for a Mediterranean climate and is said to tolerate dry cold. The leaves have a traditional use to dye fabrics pink.
|
 |
A. squarrosa, (Syn: A. concinna, A. zanzibarica) a creeping species that grows hanging down limestone cliffs in Socotra. It is often confused with Aloe juvenna but has larger rosettes with longer, often recurved white-spotted lanceolate leaves edged with triangular teeth. The unbranched inflorescence carries a cluster of tubular red flowers with greenish tips.
Although not uncommon in cultivation, the wild population is small and threatened by grazing.
|
 |
Aloe striatula (Hardy Aloe) from the Eastern Cape of South Africa and Southern Lesotho has a rosette of narrow dark-green leaves up to 10 in long on a branching 1 in stem up to 4-6 ft tall, eventually forming a bushy clump. New stem sheaths are distinctively striped white and green (hence striatula), going brown with age. Leaf margins have well-spaced tiny teeth. The inflorescence is a dense 18 in spike of tubular yellow flowers arising from the stem below the newest leaves.
Aloe striatula is very hardy and tolerates the cold-wet English winter, providing that it is planted in a very free-draining medium. During the winter of 2008/9 my plant was covered in snow for several days. However, this species is also a drought-tolerant plant, suitable for dry-landscaping. An old plant needs staking to prevent drooping, or it could be pruned to encourage a bushy habit. The prunings can be potted up for propagation of new plants. The sap of this species is said to be an irritant.
|
 |
Aloe vacillans grows on rocky mountain slopes in the Yemen and Saudi Arabia at up to 8000 ft. The large 20 in tapering, blue-grey leaves whose margins have brown teeth, form a rosette on the end of a short stem, offsetting at the base of the stem to make clumps. The leaves may take on a bronzed colour in full sun. The branched inflorescence bears spikes of bright yellow to orange-red flowers.
|
|
|
Aloe vaombe (Malagasy Tree Aloe) from Southern Madagascar has an unbranched trunk up to 12 ft bearing a single rosette of recurved smooth green leaves with a concave cross section and marginal teeth. The leaves take on reddish tones in strong light. The inflorescence is a branched raceme bearing spikes of bright crimson tubular flowers which are attractive to birds and bees.
In its habitat this plant grows in dry thorny scrub on limestone soils.
|
Above: June 2008,
The Glasshouse, RHS Wisley. |
Aloe vera Synonyms: A. barbadensis, A. officinalis (Medicinal Aloe)
This species has been so widely naturalised and grown as a medicinal plant that its exact region of origin is a mystery. However, it's origin was probably within the Arabian peninsula. Aloe vera is probably the best known Aloe and is of considerable economic importance. Extracts of the gel from the center of the leaves are included in all manner of pharmaceutical preparations for the skin, treatment of burns and for ingestion. However, some people have allergic reactions to substances in the yellow sap under the epidermis.
The large (2 ft) blue-green, tapered, fleshy leaves forming a loose stemless rosette, have prominently toothed margins. The leaves of some clones are marked with white spots but this is a variable feature. The 2 - 3 ft inflorescence is a spike of golden-yellow tubular flowers. Some clones have orange flowers. Roots are fibrous and form a symbiotic relationship with mycorrhizal fungi.
|
Offsets are produced freely at the base of the rosettes and may be removed for propagation, which is no harder than sticking the cutting into some gritty soil. Aloe vera is not hardy and is damaged by any significant amount of frost. However, it is an undemanding house plant and a popular flowering plant for dry landscaping in Mediterranean climates.
|
|
Aloe wickensii Synonym: A. cryptopoda ( Geelaalwyn)
from Southern Africa including Mozambique, Swaziland and Mpumalanga has long tapering bluish-grey leaves, colouring up with a purple hue in bright light. Leaves have brown marginal teeth. The inflorescence is a branched spike of orange-red or yellow tubular flowers or flowers with orange-red buds opening yellow.
Natural hybridization has been reported, which may contribute to the variable flower colour of this species. Its habitat range is a Summer rainfall area.
|
|
Families of Succulent Plants 
