Moreton Bay Chestnut
Castanospermum australe
Family: Fabaceae or Leguminosae
What it is like
Other common names include Morten Bay Chestnut, Morton Bay Chestnut, Black Bean Chestnut. Moreto Bay Chestnut or Castanospermum austral is a tropical, evergreen tree of about 18-35 m tall and 5-12 m width with an erect trunk, grey to brown smooth bark, and glossy dark green leaves. The flowers are pea-shaped, yellow to orange in colour and form into clusters. The seed is edible when cooked but requires extensive leeching prior to consumption due to its high saponins content. Further, it contains castanospermine, a compound which may be useful as HIV inhibitors. C.australe has an extensive root system. The wood is durable, hard, and heavy and is used as material for construction, etc.
Castanospermum australe is an evergreen Tree growing to 25 m (82ft) by 20 m (65ft) at a slow rate. See above for USDA hardiness. It is hardy to UK zone 9. It is in leaf all year, in flower from September to October. The species is hermaphrodite (has both male and female organs) and is pollinated by Birds. It can fix Nitrogen. It is noted for attracting wildlife. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid and neutral soils and can grow in very acid soils. It cannot grow in the shade. It prefers moist soil.
Height (m): 25
Where it is found
Subtropical and tropical gallery-type rainforests and on the banks of creeks, usually in good rich moist soils.
Australia - New South Wales, Queensland.
Conservation Status: This taxon has not yet been assessed.
Countries/locations it is found in
Found In: Africa, Asia, Australia, Central America, East Africa, Fiji, Hawaii, India, Kenya, New Caledonia, Malaysia, Mozambique, Norfolk Island, Pacific, Pakistan, Papua New Guinea, SE Asia, Solomon Islands, Southern Africa, Sri Lanka, USA, Vanuatu, West Indies, Zimbabwe.
How it is used
Food
Rating: 4
Seed - cooked. The fresh raw seed contains high levels of saponins and can be harmful. The cooked seed tastes like a sweet chestnut. It probably requires considerable leeching before it is safe to eat. The Australian aborigines finely sliced the seeds and soaked them in running water for 10 days before roasting them and grinding them into a powder. This powder could be stored for later use. The seeds are about 3 - 4.5cm wide and are carried in pods 10 - 25cm long and containing 3 - 5 seeds.
Seed: includes nuts, cereals, peas and beans.
Medicine
Rating: 1
The seed yields compounds called castanospermine that are under investigation as HIV inhibitors and might be useful in the treatment of AIDS. The seedpods are astringent. Used to treat post-prandial hyperglycaemia in diabetic patients.
Astringent: Produces contraction in living tissue, reducing the flow of secretions and discharges of blood, mucus, diarrhoea etc.
Miscellany: Various medicinal actions that need more clarification.
Other
Rating: 3
Other uses rating: Medium (3/5). Flowering tree, Public open spaces, Street tree, Specimen. Agroforestry Uses: The extensive root system is used to protect riverbanks and catchment areas in Australia. Other Uses The seeds have a high saponin content. Although the report does not elaborate, the saponins could probably be used as a soap substitute. The seeds contain toxic saponins which are reportedly toxic to a serious pest of stored grain. The wood can be used as a fuel. Wood - durable, resists decay, hard, heavy, polishes well, has a high resistance to the passage of electric current. The sapwood varies from white to yellow. The heartwood is dark-brown to almost black, slightly greasy and straight grained but sometimes interlocked. Used in construction, cabinet making, carving etc. One of the most valuable woods in Australia, the sliced veneers can be good substitute for teak. The wood has a density of 700 kg /cu m.
Miscellany: A rag-bag of items that are difficult to categorise.
Wood: A list of the trees and shrubs that are noted for having useful wood.
Industrial Crop: Starch: Materials and chemicals include bioplastics, paper, cardboard, solvents, paints, glues etc. Plants are usually pods, starchy fruits, nuts & seeds, starchy trunks.
Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.
Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.
Industrial Crop: Starch: Materials and chemicals include bioplastics, paper, cardboard, solvents, paints, glues etc. Plants are usually pods, starchy fruits, nuts & seeds, starchy trunks.
Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.
Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.
Carbon Farming: Plants that can be a critical part of the solution to climate problems. The Carbon Farming Solution - Eric Toensmeier.
Nitrogen Fixer: Plants that fix nitrogen in the soil
Scented Plants: Plants noted for their scent
How it is grown
A tree of moist, lowland tropical and subtropical climates, it grows best at an elevation between 50 - 750 metres. It grows best in areas where annual daytime temperatures are within the range 20 - 32°c, but can tolerate 10 - 41°c. It prefers a mean annual rainfall in the range 1,600 - 3,200mm, but tolerates 1,000 - 3,800mm. Requires a very well-drained but moist high-grade soil and a very sunny position when grown in areas cooler than its natural climate. Prefers a pH in the range 5 - 6, tolerating 4.5 - 6.5. The crushed leaves smell like cucumbers. Flowers are produced on the old wood. The flowers are rich in nectar and are pollinated by parrots in the wild. This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots 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. Prick out the seedlings into individual deep pots as soon as they are large enough to handle and plant out when 15cm or more tall.
Best place to grow: Woodland Garden Canopy; South Wall. By. West Wall. By.
Habit: Tree
Hardiness: 8-12
Growth: Slow
Soil: Light (sandy), medium, heavy (clay)
Shade: No shade
Moisture: Moist
Things to keep in mind
The immature seed is poisonous, though mature seeds are harmless. Another report says that the raw seed is poisonous and needs treatment to render it edible.
Its other names
Local names
Other Names: Australian chestnut, Bean tree, Black bean.