Kirkia wilmsii

General Info – Summary

This monoecious Tree has underground tubers, smooth grey bark and may reach 18m high.  Impressive delicate, feathery, imparipinnate Leaves lack stipules, are deciduous and produce brilliant autumn colours.  The regular unisexual 4-merous Flowers occur in panicles.  Male: 4 stamens.  Female: superior ovary + 4 styles and staminodes are present.  Fruit: a small, woody dehiscent capsule releasing triquetrous seeds.

Description

SA Tree No. 269.

Common names: (Afr) Basterpeperboom, Bergsering, Slaploot, Wildepeperboom, Wilde-peperboom, Wit sering.  (Eng) Bastard Pepper Tree, Mountain Kirkia, Mountain Seringa, Wild Pepper Tree.  (Northern Sotho) Legaba, Modumela, Modumeta.

Family: Kirkiaceae.  This family has 2 genera Kirkia (with 3 species in southern Africa and 1 genus in Madagascar).  Leaves are often near branch ends and all lack stipules.  Individual leaves are usually opposite, compound and imparipinnate with many pairs of opposite Leaflets.  The trees are unarmed.  Flowers occur in paniculate, bracteate cymes.  Individual flowers are regular and usually unisexual.  Although the tree is monoecious (having both male and female reproductive organs on the same plant), only 1 sex appears at a time.  The Calyx has 4, more or less free Sepals.  There are 4 free imbricate Petals and usually 4 Stamens in Male Flowers and these are reduced to staminodes in Female Flowers.  Here the superior ovary (reduced in male flowers) has 4 locules, each with 1 ovule.  4 fused styles end in a capitate stigma.  The woody Fruit is clearly 4-angled, dry and splits longitudinally.  Seeds are triangular in cross section and have little or no endosperm (the starch and oil-containing tissue of many seeds; often referred to as the albumen).

Name derivation: Kirkia – named after the explorer who also visited the southern Africa – the Scotsman Captain (Sir) John Kirk (1832-1922).  He was highly regarded as a botanist.  wilmsii after the German botanist and plant collector: Dr F. Wilms (1848-1919).  He was also an apothecary (person who prepared and sold medicines and drugs) who worked in Mpumalanga Province in the Mashishing (Lydenburg) area.  There are 3 species of the genus Kirkia in southern Africa (2 in South Africa – the other is Kirkia acuminata – the white stinkwood).

Conservation: National Status:  L C. (Least Concern).  2005/06/30. (W. Foden and L. Potter).  The use of tuberous roots in local medicine and for water may become a cause of concern.

Tree

This unarmed, usually small Tree with its smooth grey Bark, may reach 11m height and several stems may be present (photo 545).  Here branching often occurs near the base.  The blunt-tipped, unarmed Branches and delicate feathery leaves help produce a rounded Crown.  Branchlets have visible leaf scars with noticeably stubby, protruding tips (photo 346).  Present are large (up to 30cm long) Tubers (swollen underground stems that are storage and regenerative organs.  These help survival during dry winter months).  In rocky areas, Roots may produce leaves.

Leaves

This deciduous tree has delicate, attractive, and feathery Leaves that develop (photo 344).  They begin growth at the ends of stubby tipped branchlets (photo 109).  In this photo, the branchlet has the visible remains of old leaves bases.  Leaves are imparipinnate (pinnately compound leaf ending in a single leaflet – photo 495).  Young Leaflets are visible and have an initially red apex (photo 806).  Each leaf is up to 15cm long and has 10-23 pairs of usually opposite, leaflets – and the single terminal one (photo 495).  Each spaced apart and hairless leaflet is translucent, narrowly ovate and up to 3 x 0,6cm.  Leaflets are pale green above and slightly lighter below – photo 495).  In this photo: each leaflet Apex tapers to a point.  The Base is often asymmetric (not equal to the opposite side (photo R495) and usually tapers or is rounded.  The usually slightly toothed leaflet Margin (photo R495) may be entire (with a continuous margin, not in any way indented).  The Petiole (leaf stalk) is up to 4cm long and Stipules (basal appendage of the petiole) are absent.  Likewise, the Petiolules (leaflet stalks) are absent or very short (photo R495).  Leaves develop an impressive red or scarlet autumn colour.

Flowers

This tree is monoecious (having both male and female reproductive organs on the same plant).  However, male and female flowers appear at different times, and this helps to ensure cross pollination.  The Flowers are actinomorphic (Regular, symmetrical.  Flowers are vertically divisible into similar halves by more than 1 plane passing through the axis).  The up to 7cm long flowers with red long stalked flowers (photo 1010) are contained in compact, many flowered, Panicles (determinate or indeterminate, much branched inflorescence with stalked flowers).  Here the flowers occur at the ends of long red Peduncles – flower stalks (5 visible in photo 1010) that arise in leaf axils (the upper angle between a lateral organ, such as a leaf, and the stem that bears it (photo 1010).  In individual flowers, the Disc (a more or less fleshy or elevated development of the receptacle) is fleshy.  The Calyx has 4 green Sepals (outermost flower whorl that initially encloses and protects the rest of the flower – photo 110).  In the Corolla, there are 4 free white overlapping Petals (photo 110).  The Male Flowers have the 4 Stamens (photo 110) arising outside the disc and alternating with the Petals (photo 110).  Here the Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) has a reduced ovary and lacks a style.  In the Female Flowers, Staminodes (sterile stamens) are present.  Here the superior Ovary is 4-locular (locule: cavity within an organ e.g., ovary, anther or fruit), and each locule has 1 ovule (egg).  The 4 fused Styles (style – more or less elongated part of the pistil situated between the ovary and the stigma) have a capitate (like a head) Stigma (the end part of the pistil that receives the pollen).  (Oct-Dec).

Fruit

The small, initially fleshy Fruit is a Capsule (a dry fruit resulting from the maturing of a compound ovary and usually opening at maturity by one or more lines of dehiscence).  The stem of the pistil expands raising the fruit beyond the rest of the flower.  The initially green capsule is sharply 4-angled (photo 963) and ages to become woody.  The now brown capsule is up to 1,2 x 0,5cm and dehisces (photo 1017) into 4 or 8 Valves (outer walls of the ovary).  These split at the base, and the central axis remain attached by a membrane at the top.  Together they resemble a small half-open umbrella.  The Seeds are triquetrous (triangular, especially in cross section) and lack endosperm (the starch and oil-containing tissue of many seeds; often referred to as the albumen).  Seeds are mainly wind dispersed.  (Jan-Apr).

Distribution & Ecology

This tree is a smaller version of the white seringa Kirkia acuminata (SA Tree Number 267).  Kirkia wilmsii Trees grow naturally on dolomitic and granite formations, in mountain slopes and rocky areas.  They also occur in Sandstone in northern Limpopo Waterberg that is alkaline with a high pH value.  Shoots may develop from exposed roots and, when they do, the leaves are not initially concentrated at the branch ends.  The tree is Endemic (Endemism is the ecological state of a species being unique to a defined geographic location) in Limpopo and Mpumalanga.  Plants occur in Gauteng, Mpumalanga e.g., Abel Erasmus Pass, and through the Drakensberg, Limpopo e.g., Bela-Bela (Warmbaths) and Sekhukhune in southern Limpopo.  Elephants are one of the few animals that consume the leaves.

Ethnobotany

A good, strong fibre can be made from the Bark of young stems, young shoots and roots.  The low-density Wood is light, greyish, coarse grained, thinly textured and not much used.  Leaves are used to feed goats in Sekhukhuneland (South Eastern Limpopo and Mpumalanga).  Plants are easily Grown from seeds (spring), and in summer from Truncheons (stem cutting from a selected plant – used to produce genetically identical new plants).  They do best in a warmish, garden with well-drained soil.  In times of need, the up to 30cm long and swollen Tuberous Roots are consumed and serve both as a food and a water supply.  This plant, with its red and golden autumn leaf colours, makes a pressive garden prospect that tolerates mild frost.  A sheltered position will promote growth.  Plant parts play a role in traditional medicine.  Tuber extracts show anti-microbial activity (AMA).  In 2004, this tree was selected as the South African Tree of the Year.

References

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

Foden, W. & Potter, L. 2005. Kirkia wilmsii Engl. National Assessment: Red List of South African Plants version 2024.1. Accessed on 2025/12/18.

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.

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

 

https://en.wikipedia.org/wiki/John_Kirk_(explorer)

http://plantzafrica.com/plantklm/kirkwill.htm

http://www.operationwildflower.org.za/index.php/albums/trees/kirkia-wilmsii-il-1-5314

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

Kirkia wilmsii: A Bapedi treatment for hypertension – ScienceDirect

Kirkia wilmsii Engl. | Plants of the World Online | Kew Science

Phytochemical and antioxidant properties of different solvent extracts of Kirkia wilmsii tubers. Asian Pacific Journal of Tropical Biomedicine 6(12). October 2016

Lou-Nita Le Roux. Lowveld National Botanical Garden. May 2004.