General Info – summary.

This common dioecious coastal Tree is a southern African endemic.  The trunk has a diameter up to 45cm and is occasionally up to 29m high with a vertically fissured bark.  It may be a dune shrub.  Simple, bitter Leaves are discolorous.  Shiny upper surface is hairless and dense velvety below.  Tiny unisexual Florets (flowers) are in bracteate capitula.  The Fruit is a cypsela.  Seeds have a wind-dispersed apical pappus.

Description.

Brachylaena discolor.

Previous Names: Brachylaena discolor DC. subsp. discolor, Brachylaena discolor DC. subsp. discolor var. discolor, Brachylaena discolor DC. subsp. discolor var. mossambicensis Paiva, Brachylaena natalensis  Brachylaena natalensis.

SA Tree No. 724.

Common names: (Afr) Bosvaalbos, Kreukelboom, Kusvaalbos, Lepelboom, Vaalbos.  (Eng) Coast Silver Leaf, Coastal Silver-oak.  (isiXhosa) Isiphaluga, Isiduli, Umpatha.  (isiZulu) Iphahla, Isiphahluka, Umduli, Umphahla.  (siSwati) umPhahla.  (Xitsonga) apahla.

Family: Asteraceae, Compositae. (Daisy family: includes sunflowers, lettuce, chicory, marigolds).  There are in excess of 1 900 genera and close to 33 000 species.  This is possibly the second biggest plant family.  In southern Africa, there are 246 genera and about 2 300 species.  Local genera containing trees on this website include Brachylaena, Oldenburgia and Tarchonanthus.  Some members have flowers grouped in heads and the whole head may appear to be a single flower – like the “sunflower”.  Surrounding each flower are bracts.  Individual Flowers have sepals replaced by a pappus which may be bristle, plume, scale or awn like.  Individual flowers are called Florets that may have 5 fused petals.  The inferior Ovary contains one Ovule and the Style has 2 lobes.

Name derivation: Brachylaena – short cloak: referring to the short floral bracts.  discolour – 2 colours: referring to the 2-toned upper and lower leaf surfaces.  There are 9 species of the genus Brachylaena in southern Africa.  This genus is restricted to Africa, Madagascar and associated islands.  All species lack ray florets and are dioecious (unisexual floral structures with functional male and female parts on separate plants).

Conservation: National Status: L C (Least Concern).  Assessed: 2018. (L. von Staden).

Tree

This single stemmed Tree is up to 12m high (usually less) and has a Trunk that may reach a diameter of 45cm.  It is often a multi-stemmed shrub.  The tough, dark grey to brownish grey Bark becomes rough, hairless and vertically fissured (photos 1 048, 340 & 347).  The many indiscriminately arranged dark grey or reddish-brown untidy Branches (photo 347) may be grooved and may reach down to the ground (photo 360).  The young branches are ribbed and white-felted with short-lived woolly white hairs (photo 904).  Young branches may have visible pale Lenticels (usually raised corky oval or elongated area on the plant that allows the uncontrolled interchange of gases with the environment).

Leaves

On this evergreen tree, the simple, alternate or spirally arranged Leaves are usually up to 12 x 6cm (photo 342).  Leaves are variable in shape from oblong to lanceolate or elliptic to obovate even oblanceolate (the reverse of lanceolate, the leaf is broader at the apical third than at the middle and tapers towards the base).  The Blade is thinly leathery, shiny dark green and hairless above (photo 342).  It is pale white/silvery with dense velvety hairs below – hence the species name “discolor” (photo 342).  This colour difference is distinctive and individual trees are recognisable from a distance – especially when the wind is blowing (photo 360 under Tree).  The Midrib and lateral Veins protrude below (photo 344) and are sunken above (photo 342).  These lateral veins often form a V-shape before they reach the margin (photo 344).  The Margin is wavy, almost entire or obscurely to irregularly toothed in older leaves, especially closer to the apex (photo 342).  The Apex tapers to a point (photo 342) or is almost rounded.  The Base tapers narrowly.  Here the tapering is slightly decurrent (partly wraps or has wings around the stem or petiole) – here down the Petiole (leaf stalk is up to up to 1,5cm long).  The hairy petiole is up to 1,7cm long.  Stipules (basal appendages of the petiole) are absent (photo 342).

 

Flowers

In this tree, each inflorescence is a small Capitulum (a flower head containing a dense cluster of up to 50 small Florets (flowers).  Each capitulum (photo 367) is about 11mm long with a Pedicel (stalk of a single floret) up to 5mm long).  In photo 367, each capitulum is supported by a short visible Peduncle (stalk of flower cluster).  Here the Involucre (whorls of visible green bracts) on each single capitulum is also visible.  In male flowers they are round to cup-shaped and in female flowers they are funnel or cup shapes at the base The capitula collectively form in a Panicle (an indeterminately, branched inflorescence (photo 367) that is up to 40cm long.

These trees are Dioecious (having male and female parts on separate plants) and the very small Florets are thus unisexual.  Here the Sepals are replaced by a Pappus (modified Calyx) that is bristle-like (photo 1 050).  These have been likened to a shaving brush when completely open.  The Corolla has a dull tube ending with 5 tiny recurved, light yellow petal lobes (photo 366).  In each Male floret, the 5 Stamens are attached to the style and surround the Stigma.  The Anthers are introrse (the line of dehiscence, faces towards the flower centre).  Male involucre is relatively large, and round to cup-shaped.  Here individual florets / flowers are up to 15 x 8mm and the Ovary is abortive.  In the Female capitulum (photo 366), the clearly visible creamy white 5 lobed, recurved petals of many florets are visible.  From the centre of each floret, the extending bilobed Styles are visible (photo 366).  Staminodes may be present.  The inferior Ovary has a single ovule.  The short exserted Style has 2 lobed branches that are flat to ovate-lanceolate (photo 366).  (Jul- Sep).

Fruit

The brownish to purplish Fruit is a Cypsela (a dry single-seeded fruit formed from a double ovary of which only one develops into a seed) that is up to 8mm long (photo 152).  It has an apical Pappus (modified outer perianth series of Asteraceae).  The pappus has a tuft of rough creamy bristles.  These bristles enable the seeds to be wind dispersed (photo 152).  The tiny brown Seeds lack endosperm (starch and oil containing tissue).  (Sep-Nov).

Distribution & Ecology

This drought resistant plant is common in coastal forest, riverine forests and dune bush e.g. near Port Alfred.  On the dunes, it exists mainly as a shrub.  It is also found at the edges of mangroves and northwards along the north-eastern coast of South Africa.  Trees are Located in the Eastern Cape, KwaZulu-Natal, and Mpumalanga.  They also occur up to the Lebombo Mountains in Limpopo, in southern Mozambique and Swaziland.  These trees do not occur in Namibia.  Flowers, which may cover much of the tree, are rich in nectar.  This attracts both insects and birds.  Duiker, Bushbuck and Nyala may eat the Leaves.  The trees may survive for 30 or more years.

Ethnobotany

The yellow, strong, hard and durable Wood has a relatively low density and is used as floats for fishing nets.  Other uses include making fishing spears, fence posts, boat building, hoe, pick and axe handles, hut building and for fuel.  Zulu girls use the wood for constructing string bows.  Here a gourd is used as a sounding box.  The wood ashes are used as an alkali for soap making.  The wood is suitable for carving.  Propagation is from cuttings and seeds.  The plant grows easily and quickly from seeds and makes a good hedge plant and windbreak – especially in coastal areas.  It has non-invasive roots.  These trees, together with Mimusops caffra, are also planted for dune afforestation.  Leaves have an intensely bitter taste and are not often grazed.  This is a good Honey tree.

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.

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.

von Staden, L. 2018. Brachylaena discolor DC. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2022/10/01.

 

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

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

http://kumbulanursery.co.za/plants/brachylaena-discolour

http://apps.kew.org/efloras/namedetail.do?taxon=4688&nameid=11353

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