General Info – summary

This attractive dioecious Tree with a single straight trunk – up to 30m high and 30cm wide.  Tree has vertically fissured bark.  Simple, entire and spirally arranged Leaves are discolorous.  Inflorescences are contained within panicles.  Male trees lack an ovary and in female trees, tiny Florets are in capitula.  Nectar attracts insects & birds.  Fruit is a small cypsela with attached bristles that help the wind dispersal of seeds.

Description

Brachylaena transvaalensis

Previous Names: Brachylaena discolor subsp. transvaalensis, Brachylaena discolor var. transvaalensis.

SA Tree No. 731.

Common name: (Afr) Bosvaalbos, Vaalboom.  (Eng) Forest Silver-oak, Salie.  (isiZulu) iPhahla, Umphahla.  (Northern Sotho) Mphahla.  (siSwati) iPhahla, Umphahla.  (Tshivenda) Mufhata.

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 in the Asteraceae are called Florets that usually have a base of 5 fused Petals.  The Sepals are replaced by a Pappus (is the modified calyx, the part of an individual floret, that surrounds the base of the corolla tube in flower heads of the plant family Asteraceae.  The pappus may be bristle, plume, scale or awn like.  In all members, the central florets are called Disc Florets.  In some members, excluding Brachylaena, the outer florets (Ray Florets) are also present.  These occur around the periphery of the flower.  Ray florets are usually long and brightly coloured (like the yellow outer florets in the sunflower).  Four or 5 stamens are fused to the corolla.  An inferior Ovary is present containing 1 Ovule and the Style has 2 lobes.  Each floret produces 1 Fruit with 1 Seed.

Name derivation: Brachylaena – short cloak – referring to the short floral bracts.  transvaalensis – referring to location in the former province: Transvaal (northern South Africa).  Opinions differ on the naming of some species.

Conservation: National Status: L C. (Least Concern).  Assessed: Raimondo et al. (2009).

Tree

This impressive slender, usually single Tree is tall: 10 – 20m high (photo 614).  The Stem / trunk supports the leaves, flowers and fruit.  In this plant it is single, straight and up to 30cm+ in diameter.  The plant is usually solitary or may occur in small groups.  The initially smoothish Bark is grey or brown-grey.  It ages to become rough, possibly vertically fissured (photo 953) and stringy.  Grey twigs are hairless and ribbed.  Pale, raised Lenticels (usually raised corky oval or elongated areas on the plant that allows the uncontrolled interchange of gases with the environment), which may run lengthwise, are visible on the hairless young branches.

Leaves

These usually evergreen trees may be briefly deciduous – usually dependent on their location.  The splendid thick leathery foliage has pale green young leaves (photo 606).  Mature Leaves are alternate and discolorous (having upper and lower surfaces of leaves different colours) – hairless and dark green, above whereas below the dense whitish hairs provide the white colour (photo 609).  The spirally arranged leaves may be wavy (photo 606).  They are simple (has a single blade, which may have incisions that are not deep enough to divide the blade into leaflets).  Each leaf is narrowly elliptic and usually up to 10 x 4cm (photo 609) or larger.  The Blade has veins that are sunken above and protrude below (photo 609), where they are more clearly visible.  Lateral veins end in a rough V-shape before reaching the margin (photo 609).  Apart from closer to the apex – where it is irregularly to sharply toothed, the wavy Margin is mostly entire (with a continuous margin, not in any way indented but may be hairy).  The margin may be rolled under.  The Apex is rounded or tapering to acuminate (said of an acute apex whose sides are somewhat concave and taper to a protracted point – like a drip-tip (upper leaf in photo 609).  Near the apex the leaf may be dentate (with a toothed edge – photo 609).  The Base is narrowly tapering and partly decurrent (leaf blades that partly wrap or have wings around the petiole).  The Petiole (leaf stalk) is short – up to 5mm long and is channeled on the upper side (photo 612).

Flowers

The creamy or greenish Florets (individual flowers) develop in terminal (photo 688) or axillary Capitula (false flower containing a dense cluster of many small, drab yellow Florets (flowers).  Here each is capitulum is up to 10mm long.  The tiny florets (individual flowers) are up to 5mm long.  Florets collectively make up the dense inflorescence.  Pedicels (individual flower stalks) are reduced or absent.  The Calyx develops a Pappus (modified calyx – outer perianth series of Asteraceae, borne on the ovary (photo 453).  Here the calyx is replaced by is a row of scabrid (somewhat rough in texture), tawny (yellowish-brown) Bristles.  The cylindrical Corolla tube ends with 5 lobed Petals.  Much reduced, initially green Involucre Bracts (each bract is a usually a much-reduced specialized leaf) occur in 3-7 rows below the florets/flowers (photo 654).  The bracts are imbricate (having regularly arranged, overlapping edges – (photo 654).

The tree is usually dioecious (unisexual floral structures with functional male and female parts on separate plants).  However, occasionally bisexual flowers occur.  The Male Capitula have up to 14 flowers.  The filaments are thread like and the anthers have a tail-like appendage.  The Receptacle (is that expanded tip of the flower stalk from which the floral parts develop and is greatly expanded in the Asteraceae and Ficus) is honeycombed, and slightly convex.  The Ovary is usually absent.  The Female Capitula have up to 11 florets in large axillary or terminal flowers photo 654).  The ribbed, single chambered Ovary is ovoid to oblong and has a white bilobed Stigma (photo 655).  Here bracts extend to the base of the Peduncle (stalk of a cluster of flowers).  (Jul-Sep).

Fruit

The Fruit is a small Cypsela (in Asteraceae it is a dry single-seeded fruit formed from a double ovary of which only one develops into a seed).  The small fruit has an apical tuft of creamy-brown bristles (photo 368) that aid wind dispersal of the seeds.  After seed dispersal, the remains of the now whitish Bracts are visible (photo 366).  (Aug-Nov).

Distribution & Ecology

This is a medium altitude Tree located in different inland forest types: including evergreen, deciduous forests, forest margins, riverine forests and wooded grasslands.  They occur in KwaZulu-Natal – along the escarpment, Mpumalanga, Limpopo and in Eswatini (Swaziland).  The plentiful Nectar attracts insects including flies and bees.  Insectivorous or carnivorous birds that visit the Trees include Flycatchers, Shrikes and Prinias (small insectivorous birds).  Bushbuck and Kudu browse the Leaves.

Ethnobotany

The hard tough fine-grained and elastic Wood is durable and used for implement handles – including for axes and hoes, boat building, fence posts and hut construction.  The very large trees are usually hollow and unsound.  This is a good garden tree and propagation is through seeds or cuttings.  In order to produce fruit both male and female plants are needed.  Here cuttings from male and female plants will help ensure this.  The Roots are non-invasive.  The tree grows best in full sun and is frost hardy.  Aqueous extracts from the plant have shown some antibacterial activity.  Plant parts are used in local medicine.  This plant is frost hardy and lacks aggressive roots – making is suitable for medium to large gardens.

References

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

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

Foden, W. & Potter, L. 2005. Brachylaena transvaalensis E.Phillips & Schweick. National Assessment: Red List of South African Plants version . Accessed on 2024/10/25.

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://www.plantzafrica.com/templates/voteplant.php

http://www.operationwildflower.org.za/index.php/component/joomgallery/trees/brachylaena-transvaalensis-252

http://iscantree.co.za/brachylaena-transvaalensis-bosvaalbos-forest-silver-oak/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4364486/

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

ASTERACEAE A NOTE ON THE BRACHYLAENA DISCOLOR COMPLEX.