General Info – summary

This Tree has pale grey bark, is up to 15m high & branches have tough spines.  Wood is hard & dense.  The simple, hairless, thick, leathery, stiff & alternatively arranged Leaves are usually entire.  Tiny, greenish, 5-merous, monoecious & unisexual Flowers lack petals & are in cymes.  The sessile, 1 locular, superior ovary is pubescent & has 2 long persistent styles.  Indehiscent Fruit is an orange drupe & seeds lack endosperm.

Description

Chaetacme aristate

Previous Names: Chaetacme aristata var. kamerunensis, Chaetacme aristata var. longifolia, Chaetacme aristata var. nitida, Chaetacme madagascariensis, Chaetacme microcarpa, Chaetacme microcarpa var. crenata, Chaetacme nitida, Chaetacme serrata, Chaetachme serrata.

SA Tree No. 43.

Common names: (Afr) Basterwitpeer, Basterwitpeerhout, Baster-witpeer, Doringolm.  (Eng) Thorny Elm.  (isiXhosa) Umkaboti, Umkhovothi.  (isiZulu) Umbhangbangwe (it catches the leopard – referring to the spines), Umkhovothi.  (siSwati) umbambangwe.  (Tshivenda) Mula-nguluvhe, Muthavhalunzhi.

Family Ulmaceae. This family of 9 genera and 45+ species – at the moment.  Species includes the elms – in the genus Ulmus.  Family members have leaves and bark with mucilaginous substances.   Plants may be evergreen or deciduous.  Leaves are simple and may have an asymmetrical base and are often alternately arranged.  The small Flowers lack petals and are bisexual or unisexual.  The indehiscent Fruit may be a drupe, nut or samara. Wood is usually used for furniture.

Name derivation: Chaetacme – referring to the bristle tipped leaves.  aristata– with an awn, a fine bristle.  Chaetacme aristata is the only species in South Africa.

Conservation: National Status: L. C. Least Concern.  Assessment: 2009 (W. Foden and L. Potter).

Tree

This Tree may reach 13m high and can produces a dense canopy.  The plant may also be a vigorous shrub that may scramble.  Tough, straight, single or paired Spines occur on branches (photos 517 & 526 – under Leaves).  Spines are more numerous on coppice growth (if young tree stems are repeatedly cut or burned down to near ground level this may cause regrowth from the stump or roots).  Here spines may be larger and paired.  The Stem (main axis of the plant, the leaf and flower bearing as distinguished from the root-bearing axis) may be fluted (grooved, funnelled, channelled – photo 664).  The young branches are initially green (photo 524) with light coloured longitudinally Lenticels (a usually raised corky oval or elongated areas on the plant that allows the uncontrolled interchange of gases with the environment).  The Bark becomes pale grey.  Branches may occur low-down.  Branchlets (a small branch or division of a branch – especially a terminal division; usually applied to branches of the current or preceding year) tend to zigzag between nodes (photo 526 under Leaves).

Leaves

The simple, hairless, thick, slightly leathery and stiff Leaves are alternatively arranged.  Margins are rolled under and usually entire (with a continuous margin), but occasionally sharply toothed.  The leaves are up to 9 x 5cm (photo 520).  They are minutely punctate (with translucent or coloured dots or depressions or pits) on the lower side.  Young and coppice leaves may be serrate (saw-toothed margin with teeth pointing forward).  Leaf shape varies from elliptic to lanceolate or ovate.  The blade is often widest above the central part.  The Apex is broadly tapering to rounded, often notched and has a hair-like bristle at the tip (photos 520 here & 522 under fruit).  The tapering to rounded Base may be slightly lobed (photo 520).  It is slightly asymmetric (not equal to the opposite side).   The upper surface is dark green and glossy (photo 520).   The lower surface is a lot lighter (photo 520).  All veins are clearly visible when the leaf is held against a strong light – in this case the sun (photo 824).  Here initially parallel lateral Veins are visible and the lateral veins loop before reaching the margins.  In the field a hand lens will help.  The Midrib is clearly visible on both sides and protrudes below (photo 520).  The relatively wide Petiole (leaf stalk) is up to 1cm long and grooved on the upper surface (photo 520).  Terminal buds are enclosed by large, leathery Stipules (basal appendages of the petiole).  They are joined to form a sheath over the young bud.  However, they are caduceus (an organ or part thereof is easily detached and shed early).  Straight Spines develop with the leaves at nodes and usually occur in leaf axils (photo 526).

Flowers

The small greenish (photo 204), 5-merous Flowers (floral parts in 5’s) are monoecious (having both male and female reproductive organs on the same plant).  However, individual flowers are unisexual.  Flowers each rest on a short pedicel (stalk of a single flower – photo 204E) and are single or occur in cymes (a broad, more or less flat-topped, determinate flower cluster, with central flowers opening first).  Small Bracts (any leaf associated with a flower is called a bract).  Bracts may be much reduced, scale like and subtend the flowers.  The Calyx has 5 green and deeply concave lobes, with inflexed sides.  Petals are absent (photo 204E).  Small Male Flowers may grow in clusters in leaf axils and have 5 Stamens which emerge from the calyx lobes (photo 204E).  The Anthers are 2-thecous (with 2 pollen sacs) and dehisce through longitudinal slits.  Pistillodes (sterile, rudimental pistils are present in male flower).  In the solitary Female Flowers, staminodes (sterile stamens) are absent.  Female buds are imbricate (having regularly arranged, overlapping edges, as roof tiles).  The sessile, 1 locular, superior Ovary is pubescent (hairy).  Two long unbranched hairy persistent Styles are present.  (Sep-Dec).

Fruit

The thinly fleshy, almost spherical Fruit is a Drupe (a fleshy, 1-seeded indehiscent fruit with the seed enclosed in a stony endocarp; stone fruit – like a peach) with apical protruding remains of the stigma (photo 522 and 510).  Ripe fruit is pink or yellowish, about 1,5cm wide and rests on a pedicel (the single stalk of a flower (photo 510).  Seeds lack endosperm (the starch and oil-containing tissue of many seeds; often referred to as the albumen).  (Jan-Sep).

Distribution & Ecology

These Trees are not endemic in South Africa.  They grows primarily in a wet tropical biome.  They occur naturally in the Western Cape e.g.  Knysna, Eastern Cape, KwaZulu-Natal e.g. near Durban, Gauteng, Mpumalanga, Limpopo and North West.  Beyond South Africa they occur in Eswatini (Swaziland), Mozambique (mainly south and central), West Africa, Sudan and Madagascar.  These plants are riparian (relating to wetlands adjacent to rivers and streams).  They also grow in wooded grasslands near the coast and in the bushveld up to an altitude of 1 400m.  Many animals including Nyala and Black Rhino graze Leaves.  Rhino also eat the Bark.  Butterfly larvae of the Blue-spotted Emperor or Blue spotted Charaxes (Charaxes cithaeron cithaeron) and the Forest King Emperor (Charaxes xiphares) also feed on the leaves.  The Purple-crested Turaco (Purple-crested Loerie), the Thick-billed Weaver and bats eat the Fruit.

Ethnobotany

The dense Wood is hard, and tough.  It is difficult to cut and not much used.  However, it has been used to make fighting sticks, some musical instruments and small ornaments.  Traditional medicine makes use of the Bark and Roots.  In local villages, the spiny branches may be used as fences.

References

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

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

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

Foden, W. & Potter, L. 2005. Chaetacme aristata Planch. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2022/11/15.

Ginn, P.J. McIlleron, W.G. Milstein, S. 1989. The Complete Book of Southern African Birds. Struik Publishers (PTY) LTD. Third impression 1991.

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.

 

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

http://www.biodiversityexplorer.org/plants/ulmaceae/chaetacme_aristata.htm

http://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=120100

http://www.theplantlist.org/browse/A/Ulmaceae/Chaetacme/