General Info – summary

Usually dioecious, small shrub or Tree to 5m high has resinous twigs and leaves.  Finely fissured grey bark has red underbark.  Simple, narrow, hairless & entire Leaves lack stipules.  Small, wind pollinated, 4-merous Flowers in racemes and lack petals.  Male flowers have 4-8 stamens.  The Female superior ovary has 2 ovules per locule.  Fruit a capsule with 2-3 membranous wings.  Dark seeds are small and shiny.

Description

Dodonaea viscosa

(2 varities in SA)

1. var. angustifolia: SA Tree no 437. Has a narrow leaf – Latin angustus (narrow) and folium (leaf).  Previous names: Dodonaea angustifolia, Dodonaea thunbergiana, Dodonaea thunbergiana. var. linearis, Dodonaea viscosa subsp. angustifolia.  Common names: (Afr) Bosysterhout, Sandolien, Sandolyf, Ysterbos, Ysterhouttoppe.  (Eng) Narrow-leaf Sand Olive, Olive, Sand Olive.  (siSwati) Iheji.

2. var. viscosa: SA Tree no 437.1. Has longer, usually wider leaves with conspicuous veins.           Previous name: Dodonaea viscosa Jacq. subsp. viscosa.  Common names: (Afr) Makkaree, Sandolien.  (Eng) Sand-olive.

Family: Sapindaceae: (Soapberry and Litchi family).  This family has 135 genera and about 1 800 species including lianas, herbs and trees.  The alternate, usually pinnately compound Leaves often lack stipules (leaf stalk) and have a swollen base.  The small, usually unisexual, Flowers may be regular or irregular and develop in racemes or panicles.  The Calyx has 4-5 lobes and, when present, the Corolla has 3-5 petals (petals are absent in Dodonaea).  There are between 5 and 24 Stamens, which have free Filaments, and the Anthers have 2 pollen sacs.  The superior Ovary usually has 1 style with a stigma.  There are 27 species in 14 genera in southern Africa.  Local genera with trees on this website include Allophylus, Atalaya, Dodonaea, Erythrophysa, Filicium, Hippobromus, Pappea, Smelophyllum and Stadmannia.

Name derivation:  Dodonaea – after Rembert Dodoens (1517-1585); a botanist and professor of medicine at Leiden.  His translated book “Histoire des Plantes” was and used as a reference book for more than 200 years.  viscosa sticky or resinous – referring to the gummy leaves.  All species of Dodonaea are trees or shrubs and have flowers that lack petals.

Conservation: National Status: L. C. Least Concern.  Assessment date: 2006. Assessor: F. Cholo.

Tree

This Tree, with its low branches, is usually up to 5m high in South Africa and may reach 9m further north.  It is usually a multi-stemmed shrub (photo 402).  The Bark is grey, finely fissured and longitudinally striated, revealing a red underbark (photo 395).  Resinous, smooth and hairy Twigs (1-year-old current branch segments) are angular and reddish brown/grey (photo 360).

Leaves

The hairless, variable and alternate or spirally arranged Leaves are borne towards the ends of branches (photo 360 above).  The drooping leaves on this evergreen plant are glossy, light olive green above and lighter below (photo 397).  They are simple (have a single blade which may have incisions that are not deep enough to divide the blade into leaflets – photo 400).  The Margins are entire (with a continuous margin, not in any way indented).  Leaves are sticky, resinous and may be wavy.  The resin makes the leaves shine and this helps with identification.   Leaf shape is narrowly to widely elliptic or oblanceolate (the reverse of lanceolate, the leaf is broader at the apical third than at the middle and tapers towards the base – photo 359).  The Apex and Base are both narrowly tapering (the base more so).  The Midrib is clearly visible on both sides.  The lateral veins are slightly more visible below and are best seen when viewed against a strong light (photo 359).  The morning sun was used here – showing the neat, initially parallel lateral veins.  In this photo, the veins loop and join shortly before reaching the margin.  The Petiole (leaf stalk – photo 397) is up to 6mm long and Stipules (basal appendages of the petiole) are absent.  (Apr-Sep).

Flowers

This plant is usually dioecious (unisexual floral structures with male and female parts on separate plants (photos 409 & 355).  The greenish yellow 4-merous Flowers may also be bisexual.  Each flower rests on a slender Pedicel (stalk of a single flower – photo 356) that is up to 4cm long.  The flowers occur in axillary positions or at branch ends (photo 409).  The many flowers are contained in Racemes (a simple, unbranched, indeterminate inflorescence with stalked flowers).  The Calyx has 3-7 hairy Sepals (4-green in photo 356).  The absent Corolla Petals may be an adaptation to Anemophilous (wind pollination).  There are 4-8 Stamens in Male Flowers (8 in photo 355).  Here the ovary is absent.  The longitudinally dehiscent Anthers (photo 357) are much longer than the Filaments (the slender stalk that supports the anther).  The ovary is rudimentary in male flowers.  In Female flowers, (photo 409) the stamens are rudimentary or sterile.  Here both the calyx and pedicel are red, and the protruding Style is yellow.  The protruding Style tip has at least 3 divisions (photo 409 enlarged) and each division is up to 7mm long.  The 2-4 locular, sessile and superior Ovary has 2 ovules in each locule.   (Apr-Aug).

Fruit

In photo 07 of the young pendulous fruit, the calyx and remains of the now black style are visible.  The Fruit is a characteristic membranous Capsule (a dry fruit resulting from the maturing of a compound ovary, which usually opens at maturity by one or more lines of dehiscence).  The capsules only develop on female or bisexual plants.  They are up to 16mm wide, including the 2-3 papery wings (photo 185).   The fruit somewhat resemble those of Combretum but is smaller and has less than 4 wings.  The impressive fruit appear in large numbers, and initially, are almost flower-like (photo 389).  The papery Wings aid the dispersion by wind.  As they mature – which can take 11 months, they change from light green to pink and finally brown (photo 101).  These attractive colours may occur simultaneously.  The small, dark shiny Seeds (photo 101) have a blunt ridge and are without endosperm (the starch and oil-containing tissue of many seeds; often referred to as the albumen).  May-Jan.

Distribution & Ecology

These Trees have a wide distribution throughout the tropics of the world including Australia and are widespread in South America.  They are found in coastal dunes, woodland, flat and disturbed areas, within mountains, dry forest and in wide ranging rainfall areas.  These areas include moist margins of evergreen forests to dry semi desert.  The plants are widespread in forest margins and sandy areas – including sand dunes and rocky wooded hill slopes.  This plant may develop in abandoned cultivated land, where it may promote the growth of forest trees.  In South Africa, they are often found on the northern slopes.  Here they occur provincially in the North West, Western Cape, Eastern Cape, Kwa-Zulu Natal, Gauteng and Mpumalanga.  Beyond South Africa they occur in Siswati (Swaziland), Mozambique, Namibia and northwards into tropical Africa.   CAM (Crassulacean acid metabolism) photosynthesis can occur. (Here the stomata only open at night to preserve moisture.  During the night, they collect and store carbon dioxide to use during the day for photosynthesis.  This involves closing the Stomata (structures utilising 2 guard cells, which, unlike lenticels, can control the gaseous exchange between the plant and the surrounding atmosphere) during the day – the opposite of most plants.  In this way, they substantially reduce loss of water due to evaporation.  The stomata then open at night to absorb carbon dioxide, which is stored until daylight and is then used to complete the photosynthesis process.  CAM photosynthesis also occurs in many other plants including pineapples.

Viscum capense is a bird dispersed endemic Cape mistletoe that may grow on the stem.  It is a Hemi-parasite – (for water and mineral salts but remains photosynthetic).  White, sap-sucking scale insect infestation may occur.  These insects drain water from the plant and often have a mutualistic relationship with ants.  The resinous leaf surface may be the reason that the plants are not often grazed.

Ethnobotany

This plant is used in local medicine and is easily grown from cuttings.  In order to ensure fruit production use cuttings from both male and female plants. If seeds are used, they should be soaked in hot water before planting.  Plant the developing seedlings in direct sunlight in order to allow the red fruit colour to be emphasised.  This is a useful, fast growing, garden plant that is drought and fire resistant.  It is used to consolidate sand and reclaim marshes.  The Wood is very hard and used as fuel, and to make walking sticks, axe handles etc.

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.

Cholo, F. 2006. Dodonaea viscosa Jacq. var. angustifolia (L.f.) Benth. National Assessment: Red List of South African Plants version . Accessed on 2024/12/12.

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.

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.

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

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

http://pza.sanbi.org/dodonaea-viscosa-var-angustifolia

Crassulacean acid metabolism – Wikipedia