Eucalyptus robusta Sm.
Swamp mahogany, Iron bark
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
One of the most widely planted eucalypts, this has moderately hard and heavy
wood (sp. grav. 0.51) which is strong but brittle and stiff, elastic,
coarse-textured, and fairly straight-grained but with some interlocking.
Difficult to season and split, it works well and takes a good polish, and is
durable in contact with the ground. The wood is employed in general
construction, for underground piling, utility poles, fenceposts, and firewood.
An attractive ornamental honey-producing tree, it is also planted as a
windbreak. The plant is used as an insecticide in China (Perry, 1980).
Reported to be preventitive, swamp mahogany is a folk remedy for abscesses,
boils, cellulitis, colds, dysentery, encephalitis, enteritis, erysipelas, flu,
gangrene, mastitis, and sores (Duke and Wain, 1981).
The kino contains the antibiotic citriodorol. Leaves and fruits were positive
for flavonoids, sterols, and tannins. The bark contains only 1.4% tannin,
while the leaves may contain 12% (Watt and Breyer-Brandwijk, 1962). Leaves
contain 0.16% essential oil, with aromadendren (or aromadendral) and pinene.
Evergreen tree 2440 m with relatively large, short, straight, trunk 11.2 m in
diam. ca half the height of the tree. Trunk may have air roots. Bark gray or
brown, reddish brown beneath surface, very thick, rough, deeply furrowed,
fibrous. Leaves alternate, blades broadly lanceolate, 1018 cm long, 36 cm
wide, acuminate, acute at base and often with curved, unequal sides, glabrous,
thick, leathery, stiff, shiny or dull dark green upper surface, dull light
green beneath. Petiole to 25 mm, umbels single at leaf base, to 6 cm long,
peduncle 23 cm. Flowers 510, equally short-stalked, large, 3 cm across. Buds
pyriform, 1220 mm long, 710 mm wide. Stamens many, threadlike, spreading,
white or cream-colored, ca 12 mm long, anthers oblong with large oblong gland.
Pistil with inferior 34-celled ovary and straight, stout style. Capsules
several in rounded cluster, stalked, 1215 mm long, 1012 mm wide. Seeds tiny,
dull light brown, 12 mm long (Little, 1983).
The hybrid with E. grandis is regarded as having better firewood
Native to southeastern Australia on a very narrow coastal strip (0100 m
elev.), but now widely introduced in tropical and subtropical areas. According
to Little (1983), it is the best adapted species to Puerto Rico. Cultivated,
for example, in Angola, Argentina, Arizona, Brazil, California, Cameroon,
China, Congo, Costa Rica, Florida, Ghana, India, Indonesia, Israel, Ivory
Coast, Malagasy, Malaysia, Mauritus, New Hebrides, Nigeria, Peru, Philippines,
Puerto Rico, Sri Lanka, Tanzania, and Vietnam.
Estimated to range from Tropical Dry to Moist through Frostfree Subtropical
Very Dry to Moist Forest Life Zones, swamp mahogany is estimated to tolerate
annual precipitation of 8 to 15 dm, annual temperature of 18 to 25°C, and pH
of 5 to 7.5. Where native, this species is found mainly in swamps and at the
edge of brackish estuaries. It grows better on slopes, but doesn't compete as
well as the mixed forest species (Little, 1983).
Out of a gram of seed, about 100 germinate. Seed is usually sown, immediately
after collecting and sundrying.
In Malaysia, it starts fruiting as early as year 4. Fruits take two years to
ripen in China. Fruits are collected when the capsules start to turn black.
In Argentina, 5 year old stands 9 m tall (1,583 trees/ha) had a basal area of
10 m2 and a volume of 89 m3 for an average of 18
m3/ha/yr. Webb et al. (1980) report wood yields of 1428
m3/ha/yr. In Malaysia, the MAI was 4 cm planted under shade, 6
planted in slash/burn situation, and 11 planted in an abandoned vegetable
garden (Fenton et al., 1977).
Little (1983) mentions the use of the species for fuel, but it was not
recommended by NAS (1980a). Planted for fuel reserves at 1,0002,000 m
elevation in Sri Lanka (MacMillan, 1925). Comparing potential energy trees for
Panama, Curtis and Duke (1982) cite Puerto Rico studies showing green weight of
14,556 kg/ha for Eucalyptus robusta, 8,922 for Albizia procera,
6,932 for Casuarina equisetifolia, 4,360 for Leucaena (K-8), 599
kg only for native Leucaena, and only 402 for Cassia siamea. The
data from Puerto Rico were provided by a team promoting energy grasses as
energy sources. They concluded that energy grasses will produce 67.5 times
more green biomass. They cited 53 MT for sordan, 82 for napier grass, and 84
MT/ha DM for sugarcane (in 12 months). Perhaps the data of Smith and Dowd, in
Florida, are equally reliable. They projected only ca 6 MT/ha for Eucalyptus
(perhaps E. grandis, robusta, or viminalis) with ca
60 for napier grass, 3254 for sugarcane, and 1637 for sorghum, only 22 for
sordan. Both the Puerto Rican and Florida tabulations suggest that the energy
grasses may be 10 times as productive of DM as Eucalyptus. Eucalyptus scored
lower than Melaleuca on yield (ca 6 MT/ha/yr) and nothing has as high a heating
value as the bark of Melaleuca (>25,000 kj/kg). The stemwood (density 0.53
g/cm3) ofi E. robusta had a heat value of 19,628 kj/kg, the
stembark (0.22 g/cm3), 18,074 (Wang et al., 1982).
Complete list of references for Duke, Handbook of Energy Crops
- Curtis, C.R. and Duke, J.A. 1982. An assessment of land biomass and energy
potential for the Republic of Panama. vol. 3. Institute of Energy Conversion.
- Duke, J.A. and Wain, K.K. 1981. Medicinal plants of the world. Computer index
with more than 85,000 entries. 3 vols.
- Fenton, R., Roper, R.E., and Watt, G.R. 1977. Lowland tropical hardwoods.
External Aid Division, Ministry of Foreign Affairs. Wellington, N.Z.
- Little, E.L. Jr. 1983. Common fuelwood crops: a handbook for their
identification. McClain Printing Co., Parsons, WV.
- MacMillan, H.F. 1925. Tropical gardening and planting. 3rd ed. Times of Ceylon
Co., Ltd., Colombo.
- N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production.
National Academy of Sciences, Washington, DC.
- Perry, L.M. 1980. Medicinal plants of east and southeast Asia. MIT Press,
- Wang, S.L., Huffman, J.B., and Rockwood, D.L. 1982. Qualitative evaluation of
fuelwood in Floridaa summary report. Econ. Bot. 36(4):381388.
- Watt, J.M. and Breyer-Brandwijk, M.G. 1962. The medicinal and poisonous plants
of southern and eastern Africa. 2nd ed. E.&S. Livingstone, Ltd., Edinburgh
- Webb, D.E., Wood, P.J., and Smith, J. 1980. A guide to species selection for
tropical and sub-tropical plantations. Tropical Forestry Papers 15. CFI, Oxford.
Last update Tuesday, January 6, 1998 by aw