NAMES: White Ironwood / Forest White Ironwood
Wit Ysterhout (Afr)
Umozane (Zulu)
UmZane (Xhosa)
Muruvula (Tsonga)
Muhondwa (Venda)
FAMILY
Rutaceae (The Citrus family)
A large family, occurring globally, but most common in warm and temperate regions, with about 160 genera and more than 2000 species of trees, woody shrubs and a few herbs, belonging to the order Sapindales. Members can be identified by the presence of aromatic oil glands on the leaves, (usually only visible as translucent gland dots when held against direct sunlight), and perfumed, bractless flowers, generally divided into 4 or 5 parts, occurring in a cyme or solitary. Most flowers are hermaphroditic, and the leaves are typically oppositely arranged, compound, and lack stipules. Several members are of economic importance, and many are planted as ornamentals
The Ironwood typically grows as a large, elegant and straight-stemmed giant in its natural forest habitat, but is often much smaller and shrub-like in cultivation. It has attractive, silvery-grey bark, a gently rounded crown of lustrous, glistening, deep-green, aromatic foliage, picturesque purple berries and sprays of sweetly perfumed, dainty flowers that add life and beauty to any surrounding. It makes a delightfully versatile garden subject, easily trained into different shapes.
Description
HABITAT
These trees are especially prevalent in forested environments around the country, including evergreen, coastal and dry forests, also in riverine mixed shrub, bush and seaside thicket, where it is often found growing on sandy beach soils and dunes. Found from sea level to elevations of more than 1000 m, in Natal, Transkei, Limpopo, from the Eastern Cape to Gauteng, extending into tropical Africa.
DECIDUOUS/EVERGREEN
Evergreen
BARK
Smooth, light, purplish to dark grey, older trees often seen with a distinct citron colouring and crumbly texture around then base od stem. The main trunk is lofty, straight and columnar, occasionally furrowed, with a diameter of up to 140 cm. In woodland areas, the trees tend to branch higher up, while growth will be more spreading and shrub-like in open spaces.
FOLIAGE
Alternate, 3-foliate, (rarely 4 leaflets), with a viscous, glossy texture. The leaflets are narrowly elliptic, (50-125 x 15-32 mm), with narrow to rounded tips and tapered bases. Rich, deep-green on both surfaces, glabrous, conspicuously gland-dotted and aromatic, with a prominently wavy, entire margin. The lateral veins are numerous, and the petiole is large and grooved, up to 15 cm, but slender.
FLOWERS
Large, (10 – 12 cm), terminal, much-branched flowerheads, consisting of numerous insignificant blooms. Each individual flower is star-shaped and greenish-yellow. Sexes are carried on separate trees. (December to March)
FRUIT
A small (3.5 – 5mm diameter), 4-lobed, spherical, smooth and fleshy, gland-dotted, berry-like capsule with 2-4 seeds. As it ripens, it becomes leathery and black. (February to July)
HEIGHT
3-20 m, up to 35 m in its natural forest environment.
Landscaping Details
TOLERANCE
Once established, the trees are quite hardy, able to endure extended periods of moderate drought, although they do not favour very dry conditions. Young plants can be severely damaged by extreme cold, and they should be well sheltered for at least the first 3 years in very cold areas, after which they will be mildly tolerant of light frosts. They will not do well in very dry or severely cold highveld gardens.
GROWTH RATE
Moderate to fast, 0.5 to 1 m per year.
LIGHTING REQUIREMENTS
Full sun or semi-shade, but a substantial portion of direct sunlight is required daily, be it in the afternoons or mornings.
SOIL AND WATER REQUIREMENTS
The trees can tolerate poor and sandy soils, but optimum growth and development will be achieved in loamy or peaty, coarse textured soil that retains moisture well, with a fairly acidic Ph. The trees prefer areas with steady winter rainfall of not less than 500 mm, but are generally water-wise.
ADVANTAGES
The root system is non-aggressive, and the trees tolerate partial shade, so they make ideal container and bonsai subjects. They can also endure sandier soils, so they will grow well in coastal gardens and can assist with soil rehabilitation. As a single specimen in smaller or townhouse gardens, as part of a mixed bush clump or forest garden the trees are wonderfully decorative. The trees coppice well, and can be trained into a striking informal hedge or screening plant due to their shrub-like nature. In large, open-spaced gardens or on farms, they will make good shade trees.
WILDLIFE
The sweetly-scented flowers lure butterflies, bees, wasps, beetles, moths at night, and birds love to roost amongst the dense foliage. The fruits attract a host of fruit-eating bird species, and porcupines are said to devour the bark, but often end up severely damaging or killing trees. The trees are also host to several Swallowtail butterfly species.
PROPAGATION
Propagates well from fresh seeds taken from recently ripened fruits, sown into a humus rich, well-drained mixture of compost and river sand. (1:2) Keep in a temperate, bright area and water regularly, but allow time for the soil to dry out between watering. Young trees transplant well, and this can be done once they have developed at least 3 true leaves. (If seeds and fruits are desired in cultivation, both male and female forms are required, as the species are dioecious.)
MEDICINAL
The leaves contain chemical compounds such as alkaloids and limonoids, and have moderate antibacterial and antifungal properties. Extracts in various forms are used to treat respiratory infections, fever, influenza, gastric pains and rheumatism, while crushed leaves are applied topically to clean wounds and sores. The pulverised roots are said to ease menorrhagia and cardiac pains, and are also used against colic and flu. The leaves are also burnt as a fumigation agent and disinfectant.
PRACTICAL
True to the name, the wood is pale yellow to whitish, fine and evenly-grained but very hard, heavy and strong, with a slightly elastic texture. It is highly valued for furniture making, ornaments, roof beams, tool and implement handles, construction, flooring, vehicle bodies, mine props, toys, novelties, precision equipment, vats and general carpentry and turnery.
ADDITIONAL FACTS
The leaves have a striking resemblance to the Rhus genus, but the latter lacks the aromatic secretory cavities.