She-oak, kilu
Casuarina oligodon
Family: Casuarinaceae
What it is like
Casuarina oligodon is an evergreen tree with foliage consisting of slender, well-branched green to grey-green twigs bearing minute scale-leaves in whorls of 5-20. It grows up to 30 m tall and is a tropical highland species. It is considered to be one of the best firewood producing trees in the world. Its wood is hard and heavy and used as material for fences, houses, poles, and general construction. Also, it has an extensive root system making it an ideal species to control soil erosion on steep slopes.
Casuarina oligodon is an evergreen Tree growing to 25 m (82ft) by 25 m (82ft) at a medium rate. See above for USDA hardiness. It is hardy to UK zone 10. The flowers are pollinated by Wind. It can fix Nitrogen. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils and can grow in very acid and very alkaline soils. It cannot grow in the shade. It prefers moist soil.
Height (m): 25
Where it is found
Forms extensive pure stands along river beds and on ridge tops at elevations up to 2,500 metres.
Australasia - Papua New Guinea.
Conservation Status: This taxon has not yet been assessed.
Countries/locations it is found in
Indonesia, Papua New Guinea, Israel
How it is used
Food
Rating: 0
Medicine
Rating: 0
Other
Rating: 4
Other uses rating: High (4/5). Agroforestry Uses: The species has an extensive root system and is used to control soil erosion on steep slopes. Fallen casuarina foliage provide a good protective layer against soil erosion and helps rebuild soils and protect unstable sites. It is used in reforesting grasslands in the highlands of Papua New Guinea because it competes well with grasses such as Imperata cylindrica, Saccharum robustum and Themeda australis. With its ability to improve soil fertility by fixing atmospheric nitrogen and with its leaf litter, the tree has been found to provide good shade and growing conditions for coffee. The tree is planted as an intercrop in subsistence food gardens and as a fallow intercrop. One of the other main uses of this species is as wind breaks and, in its natural range, it can be seen planted around whole villages, protecting them from strong winds. Other Uses: The wood is generally hard and heavy and tends to split when sawn. Split wood is used to construct fences and houses. Round posts for construction, poles, fences suitable for use in the ground and for unprotected extension use in buildings, protected extension and intension work. Specialty uses include tool handles, shuttles and permanently submerged freshwater piles. The wood is regarded as one of the best firewoods in the world, with a calorific value of the charcoal of over 700 k cal/kg.
Charcoal: Used for fuel, drawing, deodorant, filter, fertilizer etc.
Fencing: Plants that can be used for fencing.
Fuel: Usually wood, plant materials that have been mentioned as being a good fuel.
Shelterbelt: Wind resistant plants than can be grown to provide shelter in the garden etc.
Soil conditioner: Plants grown to improve the structure of the soil. See also Green manures.
Soil reclamation: Plants that can be grown in such circumstances an the spoil tips of mines in order to restore fertility.
Soil stabilization: Plants that can be grown in places such as sand dunes in order to prevent erosion by wind, water or other agents.
Wood: A list of the trees and shrubs that are noted for having useful wood.
Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.
Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.
Minor Global Crop: These crops are already grown or traded around the world, but on a smaller scale than the global perennial staple and industrial crops, The annual value of a minor global crop is under $1 billion US. Examples include shea, carob, Brazil nuts and fibers such as ramie and sisal.
Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.
Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.
Minor Global Crop: These crops are already grown or traded around the world, but on a smaller scale than the global perennial staple and industrial crops, The annual value of a minor global crop is under $1 billion US. Examples include shea, carob, Brazil nuts and fibers such as ramie and sisal.
Carbon Farming: Plants that can be a critical part of the solution to climate problems. The Carbon Farming Solution - Eric Toensmeier.
Food Forest: Plants for Edible Forest Gardens and Food Forests.
Nitrogen Fixer: Plants that fix nitrogen in the soil
How it is grown
This is truly a tropical highland species, being found at elevations up to 2,500 metres or sometimes even higher. It grows in areas where the mean annual rainfall is in the range 1,900 - 2,600 mm, there is a high relative humidity throughout the year with a weak dry season of up to 2 months and the temperatures vary from 11 - 15°c minimum at night to 24 - 30°c maximum during the day. Prefers a sunny position. Mostly found in sandy soils along creeks and rivers in the wild, but also grows well in colluvial soils, humic brown clay soils, alluvial and meadow soils. Prefers a pH in the range 5.5 - 6.5, tolerating 4.5 - 7.5. For use as fence posts, a rotation length of 12 - 15 years is sufficient with thinnings at age 6 which could be utilized as fuel wood etc. According to Johnson (1982), the species consists of two subspecies: subsp. Oligodon and subsp. Abbreviata Subsp. Oligodon has longer leaves, up to 1mm long. It is used locally in the eastern highlands of Papua New Guinea Subsp. Abbreviata has shorter leaves up to 0.5mm long. It is used to restore soil fertility and control soil erosion in the N Baliem valley of Irian Jaya. This species has a symbiotic relationship with certain soil micro-organisms, these form nodules on the roots of the plants and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby.
Propagating it: Seed - sow in seed beds. Germination usually starts after 10 days, though viability is naturally low. Pricking out is carried out when the seedlings are about 50 - 60 mm high and are ready for transplanting into polythene tubes. Seed production by the species is very good. Storage is mainly in household refrigerators where they are kept until needed for sowing. No research has been carried so far into their longevity under these conditions, but appears to be orthodox for this family.
Best place to grow:
Habit: Tree
Hardiness: 10-12
Growth: Medium
Soil: Light (sandy), medium, heavy (clay)
Shade: No shade
Moisture: Moist
Things to keep in mind
Its other names
Local names
Casuarina oligodon or She-oak, kilu