Tamanu Nut Tree
- Alexandrian Laurel
- Beauty Leaf
- Dilo Oil Tree
- Oil Nut Tree
The tamanu nut tree (botanical name Calophyllum inophyllum) is an average-sized tree that usually grows up to a height of 25 meters, while a few of them may be found to be taller growing up to 35 meters in height. This species produces muggy latex whose color varies from being clear/ transparent to opaque. Often the latex of the tamanu nut tree is also white, yellow or creamy colored. The bole or stump of this tree is generally entwined or tilted and its diameter may be up to 150 cm having no support whatsoever. Usually, the external bark of the tree is distinctive having diamond or boat-shaped crevices that connect with one another as the tree matures. In addition, as the tamanu nut tree ages, its external bark also becomes smooth frequently having a burnished color (ochre) or having yellowish hue. On the other hand, the internal bark of the tree is typically chunky, supple, firm, fibrous and coated. The color of the inner bark varies from pink to red and becomes brown when exposed.
The top of the tamanu nut tree has a consistently conical shape that may at times also be hemispherical. The branches of this tree are four-angles and smoothed having plum terminal buds, each of which varies in length between 4 mm and 9 mm. The tree produces elliptical leaves that are broad, even and laminated. In fact, the shape of the tamanu nut tree leaves may be ovate, oblong or even obovate and their length varies from 8 cm to 20 cm. The leaves are either smoothed or triangular (cuneate) at the base, while they are either rounded, obtuse with a hollow notch (retuse) or (somewhat acute) subacute at the tip having latex canals which are typically not so protruding. These leaves do not have any stipules. The tree has an arrangement of flowers (inflorescence) at the axils having the form of a raceme. Generally, the inflorescences are not branched; however, at times the trees of this species may have three flowered branches each bearing five to 15 flowers, but never more than 30 flowers.
Flowers of the tamanu nut trees are generally bisexual, but occasionally structurally unisexual. The flowers are also sweet scented having perianth comprising anything between eight to 13 petals in numerous whorls that are typically whitish. A typical flower has several stamens that are yellowish in color and cluster in four bundles. The color of the anthers changes from vivid yellow through khaki to brown. Incidentally only the bisexual (hermaphroditic) flowers possess ovaries – a brilliant pink ball found at the end of the stem after the petals whither away. The tamanu nut trees bear fruits whose shape vary from round to ovoid drupe (a fruit with an outer skin) and grows up to a length of 25 mm to 50 mm. The fruits have a slender and compacted outer layer (epicarp) that is greyish-green in color and soft skinned. The nut or stone of the fruit has a hard layer and frequently has a spongy layer generally enclosing a solitary seed. The seeds have large cotyledons and radicle or the lower part of the axis of an embryo directed to the fruit’s base.
The tamanu nut tree has derived its generic name from the Greek terms ‘kalos’ denoting beautiful and ‘phullon’ meaning leaf. In other words, the generic name of this species means the beautiful-leafed tree in Greek. Similarly, the precise nickname (epithet) of this tree also has its origin in two Greek words – ‘is’ meaning fiber and ‘phullon’ denoting leaf that refers to the prominent veins on the underside of the leaves of the tamanu nut tree.
The seeds of the tamanu nut tree produce a dense oil that is deep green in color and used for therapeutic purposes or greasing the hair. The oil’s active elements are considered to renew the tissues and, hence, it is in much demand by industries manufacturing cosmetics as a valuable element in crèmes meant for skin treatment. However, it is important to note that the nuts ought to be dehydrated properly prior to cracking them. Once the nuts are cracked, the kernel that is full of oil needs to be dried further. In fact, the first neoflavone segregated by scientists in 1951 from natural reserves was calophyllolide obtained from the seeds of Calophyllum inophyllum (tamanu nut tree).
The natural oil extracted from the seeds of the tamanu nut tree was used for burning night lamps in the coastal areas of Luzon Island, located in northwest Philippines. When burnt, this oil produces a soothing scent. However, the extensive use of this oil for night lamps in these regions began to decline with the availability of kerosene and afterwards when electricity was easily available. In addition, during the World War II, the oil extracted from the nuts of tamanu nut trees was also used to generate electricity to supply power to radios.
The fruit of the tamanu nut tree can be consumed and generally it is pickled. However, one needs to exercise caution while pickling this fruit, which is known to enclose toxic substances. The timber of the tree is somewhat heavier, tougher and comparatively more enduring than the other species of Calophyllum. The surface of the wood of the tamanu nut tree is very smooth and the grain is additionally compact. The sapwood or the wood on the outer trunk of the tree has a yellowish-brown color with a pink shade. In fact, the sapwood of this tree is quite distinct from the heartwood or the central wood of the tree that is reddish-brown in color having an orange-brown or pinkish-brown shade. The wood of Calophyllum inophyllum (tamanu nut tree) is considered to be a good timber for all general purposes. In many parts of the world, the wood of this tree is in high demand for making spars, masts as well as bridges and scaffoldings as they are available in the shape of slender tall poles. As the wood is close-grained and durable, it is also used for building boats, veneer, railway sleepers and for making plywood. In addition, the timber of the tamanu nut tree is brilliant for making cabinets as it possesses a vivid reddish-brown color.
Inhabitants of different islands in the Pacific traditionally used the wood of the tamanu nut tree (Calophyllum inophyllum) to make the keel of their canoes and used the wood from breadfruit trees (Artocarpus altilis) to construct the sides of the boats. At the same time, this wood is widely used for light constructions, moulding (making wooden frames), joinery (woodwork) and flooring. The timber of Calophyllum is also used to make wooden pallets, cartwheels and axles, and diving boards. In addition, this wood is also excellent for making blowpipes and musical instruments.
The natural oil obtained from the fruit of tamanu nut tree is also used for therapeutic purposes, especially to treat conditions like ulcers, rheumatism and skin complaints. The bark of this tree is known to be astringent and a decoction prepared with the bark and latex of tamanu nut tree is also used for medicinal purposes. This decoction taken internally is especially effective for treating diarrhea and beneficial after childbirth. Externally, the decoction is used to treat skin disorders, rheumatism as well as eye ailments. Local people also use the leaves, flowers and seeds of the tree for medicinal purposes.
Habitat and cultivation
The tamanu nut tree is also cultivated for providing shade as well as reforestation and afforestation – an initiative to reclaim soil. In many places, this tree is also planted along the shores because it has proved to be effective in preventing soil erosion by the sea. While the growth of Calophyllum inophyllum or the tamanu nut tree is very sluggish, it is very popular as a roadside plantation in India. In addition, this is also an attractive ornamental plant, as it has young foliage that is crimson in color. Even the flowers of the tree are very aromatic.
The tamanu nut tree is a plant that is necessarily found growing beside a water body, especially sea shores, in the tropical climatic regions. In northern Australia, this species of trees is usually found growing higher than the high-tide level down the sea coasts. Tamanu nut trees grow in an extensive area experiencing tropical climatic conditions and its habitat extends from northern Australia to all over south-east Asia and the entire south India. As mentioned above, although it is very common to find Calophyllum inophyllum along the sea shores, this species is also found growing naturally in upcountry areas on sandy soils. Generally, this variety of tree grows and thrives well on the debris and waste (detritus) carried down by the rivers as well as on the sand and gravels deposited by the waves and wind. Tamanu nut tree grows well on soils which are usually waterless on the exterior, but the ground water table may be just a few decimetres below. Nevertheless, the water drawn by this tree is brackish or briny.
In addition to growing along the sea shores and inland sandy soils, Calophyllum inophyllum is also found thriving at river upstream, usually along the length of the river banks. The tamanu nut tree requires sufficient sunlight for growth. In addition, it grows well in places where the temperatures are controlled or toned down by their closeness to the sea as well as the sea breezes. The exposed conditions, sandy soils, heat radiation from the sand as well as the winds carrying salts make this habitat noticeably xerophytic. However, it may be noted that the trees belonging to the Calophyllum species are very susceptible to fire as well as frost.
As aforementioned, the tamanu nut trees produce bisexual flowers that are usually pollinated by insects, particularly bees. The flowering as well as the fruiting periods of Calophyllum inophyllum differ depending on the place of their growth. For instance, the trees produce flowers during May-June and occasionally in November in India. It is said that any type of asexual reproduction (apomixes) may also take place in Calophyllum bringing about polyembryony (producing in excess of one embryo). Often, the tamanu nut trees are found producing fruits round the year. As the trees usually grow along sea shores, the ripened fruits are scattered by the sea currents and also fruit bats. In case of Calophyllum inophyllum occurrence of cross breeds or hybridization is often possible because of one of the parents.
It has been found that usually the tamanu nut trees regenerate naturally close to the mother trees. The germination of seeds of this tree is delayed owing to its somewhat wood fruit that does not open as well as the solid shell of the seeds. Therefore, under normal conditions, germination of the Calophyllum inophyllum is held up for an extensive period till the peel or coating of the fruit becomes softer or decays. Nevertheless, this tree can also be regenerated from its seeds much easily given that the seeds are sown soon after the ripening.
While the capacity of the seeds to germinate is quite reasonable, several researches in the Philippines have displayed that removing the seed cover completely before sowing is not only effectual in enhancing the germination capacity of the seeds as well as lowering the time consumed by the seeds to generate under normal conditions. Such experiments carried out in the Philippines helped to lower the duration of the germination of tamanu nut tree seeds from the usual 57 days to mere 22 days. At the same time, this treatment also helped to augment the ratio of germination from a modest 63 per cent to as high as 93 per cent. It is advisable that soon after germination, the seedlings be grown in a nursery providing them with adequate shade.
The tamanu nut tree is known to be very fragile and susceptible to damage by wind. The growth rate of this tree is very sluggish. For instance, the seedlings of the tamanu nut trees are planted in the coral regions in Zanzibar and a year after they are planted the trees merely grow to a height of 90 cm. While this is considered to be an extremely slow rate of growth, it needs to be noted that the area where these trees are grown requires recurrent weeding till the time they are well established. Presently, plantation experiments are being carried out in Indonesia, where the seedlings are generally planted with a spacing of 2 x 3 meters. Generally, Calophyllum inophyllum does not form very dense thickets. Another important aspect that may help in increasing the natural regeneration of the tamanu nut trees is getting rid of the unwanted trees as well as adopting a selective cutting system.
The leaves as well as the young shoots of Calophyllum inophyllum are vulnerable to attack by a variety of insects. In addition, the fungus Fomes dochmius results in the formation of brown cuboidal rot that eventually causes the plant to decay. It has been found that another fungus recognized as Trichocoma spp. also attacks and exterminates the tamanu nut trees in India.
Scientists have done chemical analysis of the various parts – leaves, flowers, trunk and bark, of the tamanu nut tree (Calophyllum inophyllum). They have found that common tannins are present in the bark as well as the leaves of this tree. While the content of tannins is around 11.9 per cent in the bark, the leaves also enclose some amount of the substance. A decoction prepared with the bark of this tree has been at time used for coloring batik cloth in Java. On the other hand, the kernels of the tree produce around 50 to 73 per cent of viscous oil whose color varies from bluish-yellow to dark green. This oil is known as domba oil, pinnai oil or dilo oil and has a very unpleasant taste and scent. Although the oil encloses a number of resinous substances, they can be removed easily by means of refining the oil. Even the intensity of these resinous materials in the oil varies from 10 per cent to 30 per cent and, hence, it may well be used for varnishing purposes. In addition, the domba oil is said to be of very good quality to be used for manufacturing soap. In local medications, the domba oil is also used as an illuminant. On the other hand, the active elements in the oil extracted from the seeds of tamanu nut tree includes oleic, stearic, palmitic and linoleic acid. When the domba oil is blended with the resin of Vateria indica, the resultant product is used to caulk boats or make them waterproof.
The leaves of the tamanu nut trees enclose saponins and hydrocyanic acid, the latter being toxic for fish. Similarly, the latex of the tree possesses rich content of complex derivatives of coumarin – a number of them being effective in eliminating insects and pests. The wood as well as the trunk of the tree contains a significant assortment of xanthones. Among these xanthones, one called jacareubin is almost present in Calophyllum all the time. However, this chemical is very rarely found outside the plants belonging to this genus.
Collection and harvesting
The tamanu nut tree is an herbal plant native to South East Asia and Polynesia. The trunk of this tree is bequeathed with a broad and fissured bark. Trees of this species produce fruits that are similar to apricots in size. Fruits of this tree have a slender flesh with a big nut shell within. The medicinally valued tamanu nut tree oil is extracted from the nuts found inside the fruits of this tree. When the nuts have matured, they are collected and cracked to obtain the nut kernel, which is dehydrated for some time. When the nut kernels of tamanu nut trees dry out, they have an inclination to release oil. After they are dried out completely, the kernels turn to be muggy and release a pleasing scent of the tamanu oil. The oil is green in color and is obtained by means of a screw press. Since the ancient Polynesians were very familiar with the various benefits of tamanu oil, they have utilized it to treat a variety of health conditions and diseases.