General Info.

This glabrous, evergreen Tree with aromatic, peppery bark is up to 12m high and has distinctive lenticels.  Trunk has small distinct lenticel bulges.  Simple Leaves + entire margins & lack stipules.  Small bisexual Flowers have 3 sepals and 10 petals.  Ten stamens extend from a staminal tube and the single pistil with a superior ovary ends in a truncate stigma.  Roundish Fruit is a berry with shiny seeds.

Description.

Warburgia salutaris.

Previous Names: Warburgia ugandensis, Warburgia breyeri, Chibaca salutarus.

SA No. 488.

Common names:  (Afr) Koorsboom, Peperbasboom, Peperblaarboom, Peperbasboom, Peperblaarboom, Sterkbos.  (Eng) East African Greenheart, Fever Tree, Pepper-bark, Pepper-bark Tree, Pepper-leaf, Pepper-root.  (isiZulu) Amazwecehlabayo, Isibaha, Isibhaha.  (siSwati) siBhaha.  (Setswana) Molaka,  Shibaha, Xibaha.  (Tshivenda) Manakha, Mulanga.

Family Canellaceae. These plants are usually small to medium evergreen trees or shrubs with aromatic bark.  The 25+ species are located in up to 6 genera.  Conspicuous lenticels are present.  The simple entire petiolate and pinnately veined Leaves have a peppery taste.  The small regular bisexual Flowers usually have 3 coriaceous imbricate (having regularly arranged, overlapping edges, as roof tiles or fish scales) Sepals.  There are 4-12 free Petals in unlike whorls.  The outer whorl of petals is usually larger and thicker.  The Anthers are monadelphous (having the stamens at least partly united into one group by their filaments) around the superior Ovary.  At least 2-5 Stigmas are present.  The Fruit is a berry (pulpy, indehiscent fruit like a grape or tomato) with a persistent calyx.  The 2 to many Seeds are shiny with a fleshy, oily endosperm (the starch and oil-containing tissue of many seeds; often referred to as the albumen).  Warburgia salutaris is the only indigenous species in southern Africa.

Name derivation: Warburgia: named after Dr Otto Warburg, 1859-1938.  He was born in Hamburg and was a German-Jewish botanist.  He was also a notable industrial agriculture expert.  He was later the founder of institute of natural history in Jerusalem.  salutaris in Latin means healthful – possibly referring to the use in herbal medicine.  Warburgia is a genus of 4 species – confined to Africa (1 in SA).

Conservation: National Status: EN (Endangered).  Assessed: 2008 (V.L. Williams, C.J. Geldenhuys, C.R. Scott-Shaw and J.E. Victor).  It is endangered partly because of over exploitation for herbal medicine.  In southern Africa Warburgia salutaris is the only species.

Tree

This erect glabrous (hairless) Tree is usually up to 12m high in South Africa.  It may be much higher in Kenya.  The young branches are smooth and brown with conspicuous, unusual yellow/orange Lenticels (usually raised corky oval or elongated area on the plant that allows the uncontrolled interchange of gases with the environment – photo 99).  These lenticels help with identification.  The Bark becomes rough and is aromatic, peppery and pungent tasting.  The inner bark is reddish.

Leaves

This is an aromatic evergreen tree.  The alternately arranged (photo 428) hairless Leaves are coriaceous (leathery) and simple (have a single blade that may have incisions that are not deep enough to divide the blade into leaflets).  They are up to 11 x 3cm (photo 117) and elliptic to lanceolate or oblanceolate and have a peppery smell when crushed.   The rolled under and possibly wavy Margin is entire (with a continuous margin, not in any way indented (photo 381).  The Apex and Base are narrowly tapering – the base more so.  Gland dots are present and may be visible as whitish dots (photo 381).  The Midrib is slightly off-centre.  It is visible above and protrudes below (photo 117).  Unless viewed against a strong light (photo 381) the smaller veins are indistinct.  The upper leaf surface is darker.  Leaves have a short Petiole (leaf stalk) that is less than 5mm long and grooved on top.  Stipules (basal appendages of the petiole) are absent.

Flowers

The small (up to 6-7mm wide) inconspicuous green or whitish Flowers (photo 38) are borne singly or in Cymes (broad, more or less flat-topped inflorescence with the central flower opening first), on short robust Pedicels (stalks of a single flower) in leaf axils (photo 38).  Flowers are bisexual and actinomorphic (Regular, symmetrical.  Flowers are vertically divisible into similar halves by more than 1 plane passing through the axis).  Each flower has 3 persistent fleshy Sepals that are imbricate (having regularly arranged, overlapping edges, as roof tiles).  There are 10 obovate, gland-dotted Petals in 2 rows of 5.  The outer 5 are thicker, larger, and less yellow than the inner 5.  There are 10 Stamens whose Filaments are united in a clear staminal tube (photo 838) that encloses the ovary and part of the style.  Stamens are more or less the same length as the petals and are attached below the ovary to the Receptacle (is that expanded tip of the flower stalk from which the floral parts develop).  The sessile Anthers are not exserted (sticking out; projecting beyond, as stamens from a perianth) and have fleshy apical appendages on the upper part of the tube. Anthers undergo longitudinal extrorse (outwards) dehiscence.  There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) with a superior one locular, elongated to oblong superior Ovary with 10-30 ovules.  Above this is a single thick Style that is truncate (appearing as if cut off at the end – photo 38 – upper LHS). It is almost enclosed within the staminal tube and has 5 stigmatic patches around the sides.  The perianth should be removed before examining the male and female parts with a hand lens.  (Feb-Apr).

Fruit

The nearly cylindrical or oval Fruit is a Berry, (pulpy, indehiscent fruit like a grape or tomato) which is up to 5cm wide and covered with glands.  The pericarp (fruit wall) of the berry is coriaceous (leathery).  The fruit is initially green (photo 239), maturing into a distinctive rough leathery purple colour with a white bloom (photo 249).  It contains the reniform (kidney-shaped) Seeds.  These shiny seeds have an oily, fleshy endosperm (the starch and oil-containing tissue of many seeds; often referred to as the albumen).  (Oct-Jan).

Distribution & Ecology

This is a tropical species and trees are found in evergreen forests, dry rocky hillsides and wet forests.  They are located in KwaZulu-Natal e.g. in coastal forests, Limpopo e.g. along the Blouberg and Soutpansberg mountains, and Mpumalanga e.g. along the Drakensberg escarpment.  They also occur in Swaziland, Malawi, Zambia, Zimbabwe e.g. in the Eastern Highlands, southern Mozambique and into tropical Africa.  The tree is drought resistant and has Coppice growth (In this case, when stems are cut or burned it causes regrowth from the stump or roots.  The smell and taste of the leaves makes this plant easier to identify.  To the north of SA the remaining 3 species occur in Africa.

Ethnobotany

The Wood may be used as timber but is not very durable and tends to split when nailed.  Heartwood is initially yellow to greenish and eventually darkens on exposure to air.  The wood is oily and is not resistant to insect attack.  The tree also possesses aromatic Oils and the glossy green Leaves are aromatic when crushed.  They have a burning taste due to the presence of chemicals produced by plants as a protection against herbivores and against infection by microorganisms.  The peppery Bark is used to treat many ailments by local herbalists.  It has also been used against witchcraft.  The tree is becoming rare but steps are now being taken to save it.  The Warburgia project is officially sponsored by Sappi to save this tree.  It involves growing of many trees in the KNP and passing some on to local communities.  Fortunately, the tree is a fast grower.  The intent is to persuade healers to use the leaves rather than bark.  Dogs can be trained to find these plants.  The plant can be Grown from seeds and cuttings.  Seeds can be stored for a short time at 3 degrees Celsius (Centigrade).  It makes a good shade tree and grows best in frost-free areas.

References

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

Burrows, J.E., Burrows, S.M., Lotter, M.C. & Schmidt, E. 2018. Trees and Shrubs Mozambique.  Publishing Print Matters (Pty) Ltd.  Noordhoek, Cape Town.

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

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.

Williams, V.L., Geldenhuys, C.J., Scott-Shaw, C.R. & Victor, J.E. 2008. Warburgia salutaris (G.Bertol.) Chiov. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2022/07/27.

Article by Petro Kotze in SANParks Times September 2015.

 

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

http://www.farmersweekly.co.za/article.aspx?id=62795&h=How-humus-can-save-the-world

http://www.plantzafrica.com/plantwxyz/warburg.htm

http://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=140560

http://www.iucnredlist.org/details/30364/0

http://www.botanicalsociety.org.za/ProjectsAndActivities/Useful%20Plants/11%20The%20Pepper-bark%20Tree%20March%202010.pdf

http://www.worldagroforestry.org/treedb2/speciesprofile.php?Spid=1731

http://posa.sanbi.org/flora/browse.php?src=SP

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

https://en.wikipedia.org/wiki/Otto_Warburg_(botanist)