General Info.

This, the tallest aloe Tree is up to 22m high and has thin roughish bark.  Recurved, amplexicaul, rosulate & deeply channelled Leaves do fall.  They lack stipules & only margins are dentate.  Regular, 3-merous, bisexual, and reddish Flowers + nectar are in racemes.  Buds have green tips.  The 3+3 stamens and the superior ovary has a single style, & both become exserted.  Fruit is a capsule with irregularly angled seeds.

Description.

Aloidendron barberae.

Previous Names: Aloe bainesii var. barberae, Aloe barberae.

SA Tree No. 28.

Common names:  (Afr) Boomaalwyn, Boom-aalwyn, Mik-aalwyn, Mikaalwyn, Oostelike Boomaalwyn.  (Eng) Eastern Tree Aloe, Tree Aloe.  (isiXhosa) Ikhala, Umgxwala, Uphondonde.  (isiZulu) Impondondo, Indlabendlazi, Inkalane-enkulu, Inkalane Enkulu, Umgxwala, Umhlabandlanzi, Umhlalampofu, Umpondonde.  (siSwati) inhlaba.

Family: Asphodelaceae (Aloe Family).  Presumably derived from Asphodel Meadows, which is a section of the Ancient Greek underworld where indifferent and ordinary souls were sent to live after death.  The family has about 40 genera and 900 species.  There are 10 genera in the South Africa.  This is a small but wide spread, mainly African family of perennial plants.  All have Anthraquinones (an aromatic, organic compound, which is the main active constituents of herbs – often used to relieve constipation and may possess antifungal and antiviral activities.  They are also widely used in dyes).  When present, the Stems are fibrous and woody.  The fleshy Leaves often have spines either on the margins or on the blades.  The outer 2 flower whorls (the Perianth) lack the classic distinction between calyx and corolla and the lobes are called Tepals.  These 2 whorls each have 3 tepals.  Flowers are usually borne on a leafless stalk arising from the rosette of leaves.  Individual flowers are regular.  The 6 Stamens are inserted in 2 whorls of 3, below the superior 3 locular Ovary.  Fruit is usually a dry Capsule.  Genera with trees on this website include Aloe, Aloidendron and Kumara.

The name Aloidendron or ‘tree aloe’ dates to 2013 and is thanks to molecular studies that are rather shaking up phylogenies and thus classifications.  The rambling aloes have also been put in their own genus: Aloiampelos.  About 20 of these are considered to be trees.

Name derivation: Aloidendron – aloe (bitter sap) + dendron (tree-like).  barberae after Mary Barber (1818-1899) who was a plant collector in the former Transkei.  Her other interests were ornithology and entomology.  She sent a specimen to KEW where it was named in 1874.  Her contribution to science is worth reading about.  Aloidendron barberae was first recorded in 1873 by the explorer and artist: Thomas Baines.

This scientific name has changed several times.  The botanist that named it perpetrated that error.  He named two specimens as one Aloe barberae and another Aloe bainesii then realised that they were the same species.  The bainesii name stuck, but it was later realised that the barberae was published first and thus has precedence, so it is the valid name.  The name Aloidendron or ‘tree aloe’ dates to 2013 and is thanks to molecular studies that are rather shaking up phylogenies and thus classifications.  The rambling aloes have also been put in their own genus: Aloiampelos.

Conservation: National Status: L C. (Least Concern).  Assessed 2018 (H. Mtshali and L. von Staden). This tree is now widely cultivated.

Tree

This succulent perennial is the Largest and Tallest aloe and is up 22m high and the trunk has a diameter of up to 1m – even wider in cultivation (photo 989).  This photo shows the widest tree trunk that I have seen.  The thickset trunk has expanding greyish Bark with thin visible remains from fallen leaves.  These leaf remnants make it rough to the touch (photo 839).  The tree often Branches about halfway up and re-branches more than once.  These branches collectively form a rounded crown (photo 390).  Like Aloidendron dichotomum, branching often occurs by dividing into 2 parts (photo 234).

Leaves

The deeply channelled and recurved (arching over and downwards – photo 841) Leaves are situated at branch ends and form a rounded rosulate (forming a rosette) crown.  They are succulent, fairly thick, long, and narrow.  Each leaf arches over and downwards and may reach 90 x 9cm.  Leaves are a dull dark green and have parallel venation that is not that easy to see.  The Margin is pale, may be pink and is dentate (with spreading, rather sharp teeth that are usually perpendicular to the margin – photos 919 & 842).  The smallish, whitish Teeth only appear on the margin.  Some teeth become brown tipped.  The Base of the leaf is amplexicaul (a large leaf base that embraces a stem – photo 921).  The Apex may end in a drip-tip (photo 841).  The old leaves do not remain on the tree.  They shrink and soon fall off the stem.  Fallen leaves leave a clear stem with small leaf scars.  They are still greenish and not very shrivelled when they fall.

Flowers

Each Inflorescence branches dichotomously low down, and each branch contains a cylindrical upward pointing raceme (simple elongated inflorescence with stalked flowers that open in succession towards the apex – photo 151).  Each raceme is about 50cm long.  Pedicels (stalks of single flowers) – are visible in photo 333 – under Fruit.  In photo 1 007, bracts (modified specialised leaf usually found with inflorescences and flowers) are clearly visible.  Individual flowers are bisexual, cylindrical and actinomorphic (Regular, symmetrical.  Flowers are vertically divisible into similar halves by more than 1 plane passing through the axis).  Flowers are rose pink or orange and each flower bud has a distinctive green tip (photo 151).  Individual flowers are up to 3,8cm long.  Young flowers are initially erect but spread at least horizontally as they develop.  This allows the insect pollinators to escape more easily. The Perianth (the 2 floral envelopes considered together, a collective term for the calyx and corolla) consists of 2 whorls of 3.  All 6 are similar, resemble petals and are referred to as Tepals.  The 6 exserted (sticking out, projecting beyond) Stamens (visible at the base of racemes in photo 151) are also in 2 whorls of 3.  The superior Ovary is trilocular (3 compartments).  The Stigma also protrudes from open flowers.  Flowers produce a great deal of nectar and the collecting sunbirds are at least partly responsible for pollination.  (Apr-Jul).

Fruit

The Fruit is a trilocular Capsule (a dry fruit resulting from the maturing of a compound ovary with more than 1 carpel).  In photo 333, pedicels, capsules, old bracts, style and stamens are still visible.  The irregularly angled Seeds are wind dispersed.

Distribution & Ecology

This Tree is found in areas of heavy summer rainfall, little frost and in coastal areas in dense bush.  It occurs in the Eastern Cape (East London) up through KwaZulu-Natal and northwards into Swaziland, Mpumalanga and Malawi.  It tends to be more common on east and south facing slopes.

Ethnobotany

This Tree grows rapidly (at least initially) from seeds and truncheons (stem cutting from a selected plant – used to produce genetically identically new plants) which should be left for a week after cutting and before planting, otherwise the ends tend to rot.  Soil should be well drained e.g. on a slope.  The plant has invasive Roots and should be kept away from buildings.  Scale insect and aphid attack is controllable with an oil-based spray.  The tree grows in almost any soil but is sensitive to heavy frost.

References

Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.

Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.

Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants. The Macmillan Company, New York. Tenth Printing 1965.

Mtshali, H. & von Staden, L. 2018. Aloidendron barberae (Dyer) Klopper & Gideon.F.Sm. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2022/08/25.

Palmer, E. & Pitman, N. 1972. Trees of southern Africa. Balkema, Amsterdam, Cape Town.

Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park. Jacana, Johannesburg.

van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa. Struik, Cape Town.

Alice Notten for explaining the name changes that have taken place.

 

http://www.plantzafrica.com/plantab/aloebarber.htm

https://www.researchgate.net/publication/259581179_All_change_in_Aloe_Haworthia_CWalker_CactusWorld312013_sm

http://www.bioone.org/doi/abs/10.1600/036364414X678044?journalCode=sbot

http://veldfloraed.blogspot.co.za/search?q=Aloidendron+barberae+

http://succulent-plant.com/families/aloaceae.html

https://en.wikipedia.org/wiki/Mary_Elizabeth_Barber