This beautiful mangrove tree is easily recognized by its large leaves, delicate white flowers and guava-like fruit that hang in long racemes.
Barringtonia racemosa has a straight, unbranched stem that leads to a rounded crown and is usually 4-8 m tall, but occasionally reaches 15 m. The bark is greyish brown to pink with white blotches and raised dots and lines. The branches are marked with leaf scars.
© Geoff Nichols
The leaves are alternate and carried in clusters at the ends of branches, are 180-320 x 55-145 mm, with petioles 5-12 mm long. The midribs are prominent on the lower side of the leaf and the branching veins are visible on both sides.
The flowers are produced on hanging racemes up to 1 m long. The buds are pinkish red and split open to bring forth masses of delicate stamens in white sprays up to 35 mm wide, which are often tinged with pink. The flowers give off a pungent, putrid yet faintly sweet odour in the morning. The fruit are quadrangular, 65 x 40 mm. Each fruit contains a single seed surrounded by spongy, fibrous flesh that provides the buoyancy that allows the fruit to be carried off with the tide.
© Geoff Nichols
Distribution and habitat
Barringtonia racemosa is mainly a coastal species that thrives under very humid, moist conditions. It is common along tropical and subtropical coasts in the Indian Ocean, starting at the east coast of South Africa. It is also common in Mozambique, Madagascar, India, Sri Lanka, Malaysia, Thailand, Laos, southern China, northern Australia, the Ryukyu Islands of Japan and a number of Polynesian islands. It does grow well under dry conditions but it cannot tolerate even mild frost.
Barringtonia racemosa is not threatened in any way.
Derivation of name and historical aspects
The genus Barringtonia contains 56 species and is named after Daines Barrington, an 18th century botanist, jurist and antiquary. The specific name racemosa refers to the long racemes on which the flowers and fruit are borne. B. racemosa is the only indigenous species of this genus occurring in South Africa. Two Asian species exist in cultivation in the Durban Botanic Gardens- B. asiatica and B. acutangula.
Barringtonia racemosa can tolerate salt water and therefore thrives under coastal and estaurine conditions. It also grows well under dry conditions where frost does not occur. The chief dispersal agent for the buoyant seeds is the tide. Although there are no records of animals eating the fruit, the presence of the trees up to 1 000 m above sea level points to an as yet unknown animal as a dispersal agent. It flowers twice a year: in spring and again from January to April. The strong scent produced by the flowers at night attract moths and nectar-feeding bats. After the flowers (petals and stamens) are shed, the inflorescences are often crowded with ants that are attracted to the nectar. It is the larval food plant for the butterfly Coeliades keithloa.
© Geoff Nichols
Uses and cultural aspects
The seeds, bark, wood and roots contain the poison saponin and is used to stun fish. The bark, which also has a high tannin content, is frequently used in powdered form for this purpose. Extracts from the plant are effective insectides and are also used medicinally in the East; in South Africa the Zulus use the fruit to treat malaria. In Bengal the seeds are used to poison people and coconut is said to be the antidote. The young leaves are edible and the bark is often used for cordage.
© Geoff Nichols
Growing Barringtonia racemosa
It grows rapidly from the seed or cuttings that are pushed into the ground. The typical substrate on which it grows is the black mud on the banks of the estuaries on South Africa 's east coast.
Split the hard outer covering of the fruit to expose the seed which is about the size of a small chicken egg. Usually a large proportion of the fruits are seedless. Place the seed in a 1:1 mixture of sand and compost kept in a warm, well-ventilated area receiving a lot of light. The seeds generally germinate in 10 to 14 days, depending upon the heat. The seedlings can be planted out into large containers or into the open ground in their second season of growth.
When growing it in a garden (or relatively dry conditions), it is best to water it regularly during the establishment phase and during winter, otherwise the plant is likely to die. In Durban and Sri Lanka the weather is such that it is used as a roadside tree. Generally B. racemosa cannot tolerate even mild frost, however, it has been grown successfully in the Highveld when kept in a greenhouse under permanently well-watered and very humid conditions.
The very large, spear-shaped leaves provide plenty of shade and any plants grown in close proximity to the tree should be shade plants that can tolerate very moist soils. It is well suited for small gardens because the horizontal branching of B. racemosa makes the canopy easy to prune to the required size. B. racemosa is deciduous, dropping its leaves for a short time in early summer before the first rains on the east coast of KwaZulu-Natal.
The wood is susceptible to sap-stain and being attacked by termites and marine borer; the sapwood is prone to attack by Lyctus borers.
References and further reading
- Beentje, H.J. 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi.
- Chantaranothai, P. 1995. Barringtonia (Lecythidaceae) in Thailand. Kew Bulletin 50: 677-694.
- Coates Palgrave, M. 2002. Keith Coates Palgarve Trees of southern Africa, edn 3. Struik, Cape Town.
- Nichols, G. 2001. A pretty tough survivor. The Farmer's Weekly 20 April: 63.
- Palmer, E. & Pitman, N. 1972. Trees of southern Africa covering all known indigenous species in the Republic of South Africa, South-West Africa, Botswana, Lesotho and Swaziland, vol. 3. Balkema, Cape Town.
- Pooley, E. 2003. The complete field guide to trees of Natal, Zululand and Transkei, edn 4. Natal Flora Publications Trust, Durban.
- Strey, R.G. 1976. Barringtonia racemosa. The Flowering Plants of Africa 43: t. 1706.
- Van Wyk, A.E. (Braam) & Van Wyk, P. 1997. Field guide to the trees of southern Africa. Struik, Cape Town.
- Internet 12-11-2007: World Agroforestry Centre, Agroforestree Database: http://www.worldagroforestrycentre.org/sea/Products/AFDbases/af/asp/SpeciesInfo.asp?SpID=307.