no previous
no next

  ― 145 ―

No. 24: Castanospermum australe,

A. Cunn

The Black Bean

(Natural Order LEGUMINOSÆ.)

Botanical description

— Genus, Castanospermum, A. Cunn.

Calyx-teeth. — Very short and broad.

Standard. — Obovate-orbicular, recurved, narrowed into a claw; wings and keel-petals shorter than the standard, all free and nearly similar, erect, oblong.

Stamens. — Ten, all free; anthers linear, versatile.

Ovary. — On a long stipes, with several ovules, tapering into an incurved style.

Stigma. — Small, terminal.

Pod. — Large, coriaceous, almost woody, turgid, two-valved, spongy inside.

Seeds. — Large, nearly globular; cotyledons thick ; radicle scarcely prominent, straight.


Leaves. — Large, unequally pinnate.

Flowers. — Large, yellow to orange, and even red; in loose axillary or lateral racemes.

Bracts small; bracteoles none.

Botanical description

— Species, C. australe, A. Cunn. in Hook. Bot. Misc., i. 241, tt. 51, 52.

A tall glabrous tree.

Leaves. — 0ne to 1 1/2 feet long; leaflets 11 to 15, ovate-elliptical or broadly oblong, shortly acuminate, 3 to 5 inches long, shortly petiolulate.

Racemes. — Under 6 inches long, either in the axils of the older leaves or on the leafless older wood; pedicels nearly 1 inch long.

Calyx. — About 8 lines long, including the turbinate base.

Standard. — Above 1 inch diameter.

Pod. — 8 or 9 inches long, about 2 inches broad, slightly falcate, almost terete, the valves hard and thick, the spongy substance inside dividing it into 3 to 5 cells, each containing a large chestnut-like seed. (B.Fl. ii. 275).

Var. brevivexillum, Bailey.

This variety differs from the normal from in that its flowers are smaller and of a canary yellow, and the standard shorter than the wings and keel-petals, of nearly the form of these, and but slightly recurved. Stamens nearly straight. (Queensland Agric. Journ. Vol. 1, where an illustrative plate is given).

  ― 146 ―

Botanical Name

— Castanospermum, from the Latin castanea, a chestnut, and spermum, a seed. The tree is confined to Australia, and in non-Australian descriptions of it the name is usually explained on the ground that "the seeds are roasted like chestnuts." This matter is alluded to later on. Australe, Latin Southern, and hence Australian.

Vernacular Names

— Because of the seeds, which are very large beans, this tree goes under the name of Bean Tree; and because of the dark colour of the wood, and partly by way of distinction from the Red Bean (Dysoxylon Muelleri), it is usually known by timber merchants as Black Bean. Moreton Bay Chestnut is an old name for the tree, because it was first found in the Moreton Bay district (Queensland).

This tree was discovered by Mr. Charles Fraser Colonial Botanist, and Mr. Allan Cunningham, a botanist then attached to the Royal Gardens at Kew, and who afterwards succeeded Mr. Fraser at the Sydney Botanic Gardens.

The plant is figured and described in Hooker's Botanical Miscellany, vol. i (1830), which contains an account of a botanical trip made by those gentlemen in the neighbourhood of Moreton Bay. A forest, "near Brisbane Town," contains "a most interesting new plant, producing fruit larger than a Spanish chestnut, by which name it is here known."

Aboriginal Names

— "Irtalie" is the name given to this tree by the aborigines of the Richmond and Clarence Rivers, New South Wales (C. Moore); "Bogum" was an aborioinal name in the northern parts of the same State; "Kongo" of the natives of the Russell River, Queensland (F. M. Bailey) "Wung-ah," of Herbert River (Q.) blacks (J. A. Boyd).


— Mr. F. M. Bailey points out that the micro-fungi, Asterina platystoma, Cooke and Massee, and Myriocephalum castanospermi, Cooke and Massee, often injure the leaflets of this tree.


— The flowers are borne on the last year's wood, bear a general resemblance to pea-flowers, though more solid and fleshy, and in colour vary from yellow, through all stages of orange, to coral red. They are very handsome, though not available for cut flowers. There are two forms, as has already been pointed out.


— Mr. C. Fraser, Superintendent of the Botanic Gardens, Sydney, "being directed to establish a public garden in Brisbane Town," carried out this task in 1828, and was accompanied by Allan Cunningham. They discovered this tree, and Fraser says:—

By the natives the fruit is eaten on all occasions; it has, when roasted, the flavour of a Spanish chestnut, and I have been assured by Europeans who have subsisted on it exclusively for two days, that no other unpleasant effect was the result than a slight pain in the bowels, and that only when it was eaten raw.

  ― 147 ―
Sir William Hooker adds a note:

Although the large and handsome seeds are eaten by the natives of Brisbane River, and by the convicts in that part of our colony, as substitutes for our Spanish chestnuts, I have found them hard, bitter, and their flavour not unlike that of an acorn.

Extended experience shows that very few stomachs can tolerate them.

The principal food of our natives is the Queensland chestnut; the beans are cut into strips, soaked in water, and then either cooked as they are, or kneaded into cakes. (J. A. Boyd, Herbert River, Q, in a letter to the author.)

The aborigines usually scrape it, by means of jagged mussel shells, into a vermicelli-like substance, prior to soaking it in water.

The beans are used as food by the aborigines, who prepare them by first steeping them in water from eight to ten days; they are then taken out, dried in the sun, roasted upon hot stones, pounded into a coarse meal, in which state they may be kept for an indefinite period. When required for use, the meal is simply mixed with water, made into a thin cake, and baked in the usual manner. In taste, cakes prepared in this way resemble a coarse ship biscuit. (C. Moore.)

A sample of starch from these beans was exhibited by Mr. Moore at the Intercolonial Exhibition of Melbourne, 1866.

The starch or flour is neither better nor worse than many of the food starches at present consumed for food. As an experiment, a chemist at Lismore once made 40 lb. of starch from the beans, which. he sold at 4d. per lb.

Dr. T. L. Bancroft, of Brisbane, has examined the beans, and is very emphatic in regard to their deleterious properties as far as man is concerned. He states that if a small piece of the bean be eaten it causes severe diarrhoea, with intense griping, and. he says it does this whether it was previously soaked in water or even roasted. He states that no poisonous. principle is removed by water, and no part of the plant is bitter.

Having considered these seeds as food for human beings, let us consider them as food for domestic animals.

Stock-owners have long waged war against this. tree, owing to the fact that cattle and horses are poisoned through eating the seeds. They are not, however, a poison in the strict sense of the term, since no alkaloid or poisonous principle was for a long period found in them. All the same, the beans kill the stock owing to their highly indigestible character, the indigestible portion in time forming a ball in the stomach. The leaves also are found to be injurious, and animals which take to eating them become very fond of them, and when taken away return long distances to these trees, and according to some accounts become affected similarly to animals which eat the Darling pea, and, if not carefully looked after, they will pine away and die. Following, are some interesting notes in regard to bean poisoning on the Richmond River:—

1883 was a dry season, and grass scarce. —— informed me that he had lost over 100 head of cattle by bean-poisoning. Next day my attention was drawn to a few cattle in the stockyard said to be poisoned by eating beans. I inquired of the stockman if he had any proof that they

  ― 148 ―
had eaten beans, when he pointed to a beast that had died the day before, and beans had been taken from its stomach. In reply to my question he said he expected some of the cattle in the yard to recover. They appeared much purged discharging thin watery foecal matter. Cattle seem to be attracted by the bright green appearance of the beans as they lie upon the ground. Many cattle and horses on the Richmond have been lost from bean-poisoning. —— lost a valuable entire horse and cattle in this way, and many others have similar experience. It appears to affect horses in a different way from cattle. —— informed me that while removing horses from a paddock in which the bean-tree was growing two of them died without previously showing any symptoms of poisoning.

The seeds are also rapidly fatal to pigs in some cases, probably when devoured on an empty stomach. Opossums are stated to be fond of them.

Knowledge was in this state when Mr. J. C. Brunnich, chemist of the Queensland Department of Agriculture, took the matter up. Following is his report, taken from the Queensland Agric. Journ., Oct., 1901, p. 422:—

For the analysis, I prepared the beans by shredding them roughly into thin slices, and determining the moisture in a fresh sample of these slices. The bulk of the sliced seeds was left exposed to the air to dry spontaneously. This air-dried sample was ground into a fairly fine flour (all passing through a sieve with thirty meshes to the inch), and this prepared flour was used for the exhaustive analysis, calculating the composition of the fresh seeds from the analysis of the air-dried flour.

The tabulated result of this analysis is as follows:—

Air-dried Flour. per cent.  Fresh Bean. per cent. 
Water  10.68  55.76 
Fat  1.06  0.52 
Chlorophyll  0.39  0.17 
Albuminoids, soluble in water  5.41  2.68 
Albuminoids, coagulated when boiling  1.18  0.59 
Albuminoids, insoluble, Legumin  4.44  2.20 
Glucoside, Saponin  14.58  7.23 
Starch  37.54  18.59 
Mucilaginous substances  3.18  1.57 
Dextrin  4.98  2.47 
Glucose  0.64  0.32 
Woody fibre  7.99  3.96 
Crude ash  2.21  1.09 
Undetermined extra matter, colouring matter, organic acids, pectin, &c., by difference  5.72  2.83 

Analysis of the Crude Ash.

per cent. 
Soluble in water  73.05 
Insoluble in water, soluble in HCl  19.70 
Unburnt carbon  7.25 
Phosphoric acid  26.17 
Chlorine  2.48 
Potash  29.81 
Soda  3.44 
Lime  6.16 
Magnesia  6.88 
Unburnt carbon  7.25 
Carbonic acid by difference  17.81 

  ― 149 ―
The result of the analysis was obtained as follows, most operations being carried out in duplicate:—

per cent.  per cent. 
Extract by petroleum spirit (boiling under 45 degrees C.)  1.02  1.10 
Extract by ether (water free) chlorophyll  0.40  0.39 
Extract by absolute alcohol, principally glucose, with a trace of tannin; no alkaloids  0.73  Lost. 
Extract by cold water  27.04  ... 

As the previous treatment with ether and absolute alcohol made some of the albuminoids insoluble, fresh watery extract of the flour was prepared.

per cent.  per cent. 
Extract by cold water of air-dried flour  28.48  27.96 

This watery extract contained:—

per cent.  per cent. 
Ash  1.65  1.60 
Total nitrogen  1.054  1.055 
Soluble albuminoids calculated from nitrogen  6.59  6.59 
Soluble albuminoids coagulated when boiling the watery extract, vegetable casein  1.18 

Precipitated by absolute alcohol:—

lst. Mucilaginous substances  3.22 3.14 
2nd. Dextrin  4.98 6.70 

When treating the watery extract with 4 vols. of absolute alcohol, there is a danger that part of the saponin is also precipitated with the dextrin, if the filtering is not done very quickly. As the second sample filtered very slowly, the dextrin contained a large amount of saponin, by giving the characteristic test, when treated with sulphuric acid.

per cent. 
Not precipated by absolute alcohol, glucose  0.64 

For comparison with the usual method of extraction, extracts with benzol and 80 per cent. boiling alcohol were also made:—

per cent. 
Extract by benzol (C6H6) boiling at 81° C.  1.43 
Extract by 80 per cent. alcohol (Sp. Gr. .8483 at 15°)  19.88 

Of this extract was :—

Soluble in abs. alcohol  2.50 
Insoluble in absolute alcohol, but soluble in water, and precipitated by sub-acetate of lead  17.16 

The saponin was determined in accordance with the method recommended by Christophson and Otten (Dragendorff's Plant Analysis, p. 68), by extracting with boiling 80 per cent. alcohol, filtering when hot, boiling off the alcohol of this extract, and precipitating the saponin with concentrated baryta water. For the quantitative determination, the residue of the flour, after having been treated and extracted with petroleum ether, ether and absolute alcohol were used, and gave in an average of several determinations--14.58 per cent. saponin. Larger quantities of the glucoside were prepared from fresh samples of the flour. The purest saponin was obtained on cooling of the alcoholic solution, in the form of a white curdy precipitate. I also separated the saponin by evaporating the alcoholic solution, precipitating with baryta water, and decomposing the baryta saponin with carbonic acid, and separating the saponin by shaking the watery solution with chloroform.

The yellowish amorphous powder obtained had a peculiar sweetish taste, was easily soluble in water, chloroform, and in hot dilute alcohol. From the solution, it was precipitated with subacetate of lead, baryta water, and also, to a slight extent, by acetate of lead, but gave no reaction with Mayer's solution. By moistening a trace of the dry saponin with strong sulphuric acid, or, better, with fuming sulphuric acid, a beautiful red colour is slowly formed, turning purple and becoming darker on standing. This colour keeps for days. A small quantity of the saponin dissolved in water forms a strong froth on shaking the solution.

Both these reactions may be shown with slices of the fresh or dried seeds, as when moistening the surface with sulphuric acid, very shortly bright red spots and streaks are formed; again, when putting a few slices of the seeds in water and shaking the mixture, a froth is formed as if soap were present.

  ― 150 ―
A peculiar reaction, which I have not seen mentioned in any of the works at my disposal, is that the sample of saponin prepared from the beans, on the addition of ammonia, dissolves in the cold with a beautiful carmine colour, which appears only gradually, and gets more brilliant as exposed to the air. After a while the colour begins to fade. and remains yellow; when heating the red colour disappears rapidly. The saponin itself is not changed, as, on evaporation of the ammoniacal solution with sulphuric acid again, the characteristic glucoside reaction is obtained. Weak caustic potash dissolves a trace of the saponin with a brick red colour, also changed into yellow on standing or heating. 1 don't know if this peculiar reaction is due to the impurity in my samples of saponin or not. The air-dried sample of the bean was also tested for alkaloids, but no trace of a bitter principle can be found in alcoholic extract or, acidulated alcoholic extracts. That the substance obtained from the hot alcoholic soluble extract is really a true saponin, is further proved by the fact that a solution of it does not reduce Fehling's copper solution. When heating a solution with dilute acids for some time, the saponin is decomposed into glucose, and into a substance, saponogin, sparingly soluble in water. The inverted saponin solution, due to the presence of glucose, acts at once on Fehling's solution. The saponogin is soluble in hot alcohol, and forms, on evaporation, a crystalline residue.

I consider the presence of a saponin in the beans undoubtedly proved, and the toxic effects of the bean are due to this glucoside.

As saponin is very soluble in water, it also shows that by soaking the crushed beans for a few days in water, as practised by our aboriginals before using the seeds as food, the poisonous principle is removed, leaving a rather valuable nutritious food.


— The bark is smooth, dirty gray externally, pale brown or yellowish internally. A tree 2 feet in diameter has a bark, say, 1/2 inch thick. It is not astringent, and therefore not to be thought of by the tanner. It is, however, bitter to the taste, and probably contains saponin, though I have not chemically examined it.

I wrote the above words concerning the bark in the Agricultural Gazette, N.S.W., Jan., 1894, p. 3, and it is interesting to find that, in 1901, Mr. Brunnich found a saponin in the seeds. On the bark may be observed numbers of lenticels. These are organs (usually slightly raised) frequently found in the periderm of both stems and roots. They correspond to the stomata of the epidermis (commonly that of the leaf), and serve, like them, to admit air to the living internal tissues.


— It is easiest described by stating it strongly resembles walnut. I have always endeavoured to urge moderation in advocating the claims of colonial timbers, feeling sure that our timbers have received a good deal of harm from indiscriminate praise; but, having kept black bean under observation for a number of years, and having caused large quantities of it to be worked up into various articles, I think very highly of it. I look upon it as scarcely inferior to walnut. People sometimes complain of it that it warps and splits a little, but it does not do this if it receives the seasoning that cabinet woods receive in the northern hemisphere. Let black bean be felled when the sap is down, and given a reasonable amount of seasoning, and I do not hesitate to say that it may be pitted against walnut without disgrace. Black bean is easier to dress than even cedar; in fact, it is almost perfection as regards the case with which a surface can be got on it. It polishes readily, but the grain is inclined to rise under polish. This timber often shows a beautiful figure; planks which have the figure in bands, like the marking of an agate, are really gorgeous.

  ― 151 ―
Mr. Allen Ransome tested some speciment sent to the Colonial and Indian Exbibition. He thus reports:

A beautifully figured brown wood. The sample sent, being very wet, was tried under somewhat unfavourable circumstances. A baluster was turned from it, and some boards and panels planed, the work from both lathe and planing machine being excellent. The wood should prove valuable for cabinetmakers, but should be thoroughly seasoned before being used, as it shrinks very much in drying.

I have already alluded to seasoning in connection with this timber but Mr. Ransome's specimen, "being very wet," is hardly a fair one from which to draw conclusions. In the building of the Austral Banking Company, in Phillip street, Sydney, I have seen black bean used for framing twelve months after felling and it was standing splendidly two years afterwards. A piece of black bean, bone dry, having been seasoned over 25 years, has a weight which corresponds to 39 lb. 8 oz. per cubic foot ; but as a rule the timber is heavier than this. Although the great use and value of this timber is for cabinet work, yet it has been used for rougher work. 1 am informed that on the Tweed River it has been used for culverts, and when free from sap it lasts well underground. Mr. Forester Pope, of Murwillumbah, also reports:

Very durable; will last any number of years under the ground.

This is more satisfactory, as for many years it was not considered to be a durable timber. It is also used for staves. The sapwood is white and thick, and of all the hundreds of New South Wales timbers with which I am acquainted, I know of no other sapwood, other than that of Spotted Gum, so readily attacked and so promptly destroyed by borers as this one. Insects speedily reduce it to a flour-like substance.


— A gum from this tree was shown in the New South Wales Court at the Paris Exhibition, 1867, but I cannot find any account of it, and it does not appear to have been examined. The bark of this tree is often glazed in patches with a gummy exudation, but I have not been able to get a quantity approximately pure. It is not likely to have commercial value as it does not appear to be soluble, but the samples seen may have been those from which the soluble portion had been washed away by the rain, leaving the insoluble, or metarabic portion. Dr. Lauterer (see p. 167) gives a note on it.


— A fair average height for the bean tree would be 60 feet or 70 feet, with a trunk diameter of 2 feet or 3 feet. At the same time it frequently attains a height of nearly double this, with a diameter of 5 feet or 6 feet.


— It is usually found growing in brush land of the very richest soil, usually near the banks of rivers in the Clarence, Richmond, and Tweed River districts, but frequently in the scrub, a considerable distance from creeks and rivers. It comes as far south as the well-known Don Dorrigo Forest Reserve, in the Bellinger River district. It is also found in Queensland, extending a considerable. distance along the coast districts, right into the tropics.

  ― 152 ―


— The tree is propagated from seed, the large "beans," and can be supplied by every nurseryman. The leaves are pinnate, as shown in the drawing, and in a mass are of more than ordinarily handsome appearance. The foliage is dark and the whole tree shapely, quite justifying Cunningham's laudatory remarks in regard to it. Those who are not familiar with the tree in its native habitat may see some magnificent specimens in the Sydney Botanic Gardens. It is one of our most beautiful native trees, always admired, and it should be more freely planted.


Plate 25: The Black Bean (Castanospermum australe, A. Cunn.) Flowers. Lithograph by M. Flockton

  • A. Calyx with stipitate ovarium.
    • (a) Stipe.
    • (b) Ovarium.
    • (c) Curved style.
  • B. Standard.
  • C. Wing and keel petals.
  • D. Stamens (enlarged).


Plate 26: The Black Bean (Castanospermum australe, A. Cunn.) Fruits. Lithograph by M. Flockton

  • A. Legumen (pod).
  • B. The same, after dehiscence by both dorsal and ventral sutures.
  • C. Bean (seed).
    • (a) Hilum.
  • D. Remains of stamens.
  • E. Persitent Calyx.
  • F. Persistent calyx,

Supplementary Material Added at the End of Volume 2

No. 24. Part VII.

Castanosperum australe, A. Cunn.


(Natural Order LEGUMIN0SÆ.)

Aboriginal Names. — See vol. i, p. 146.

Following are additional North Queensland aboriginal names, presumably of the seeds : — Cooktown, "ku-par"; Bloomfield, "marchái"; Atherton, "wakki," "mi-ran"; (Lower) Tully River scrubs, "meran"; Cape Grafton, "chonggora." — (Dr. W. E. Roth's Bulletin, quoted below.)

Fruits (seeds). — See vol. i, p. 146.

Fruit eaten. On the Bloomfield, this nut is nearly always obtainable, but, like the Entada scandens, is not relished. It is one of the worst foods to prepare, a long time being required to wash away the disagreeable flavour. It is first of all baked in a stone oven, then pounded and sifted, put into a bark trough, and treated with like the Dioscorea sativa yam (R. Hislop). At Atherton, the shells being broken, the kernels are commenced to be baked about sunrise, the covering leaves and earth being removed about mid-day. They are then cut up into very fine chips with a sharp shell, and about sunset are put into a lawyer-cane dillybag, through which the creek (i.e., running) water is made to percolate, and there it remains until the following morning when it is ready to eat. On the Lower Tally River, after the beans have been gathered, the nuts are removed and placed in heaps in the ground-ovens. After covering with leaves and sand a fire is lit on top, with the result that the nuts are practically steamed, a process occupying from a few hours up to a whole day. When removed, they are sliced up very fine with a snail- shell knife and put in dillybags in a running stream for quite a couple of days, when they are ready. If not sliced up very fine, the bitter taste remains. — (North Queensland Ethnography, Bulletin No. 3, Dr. NY. E. Roth.)

Supplementary Material Added To Volume 4

No. 24. Part VII. See also vol. ii, p. 197.

Castanospermum australe, A. Cunn. THE BLACK BEAN. (Family LEGUMINOSA.)

Leaves. — See vol. i, P. 146. Leaves of Castanospermum australe contain saponin, readily recognised by the strong frothing of an extract. I could not detect any saponin in the seeds. (Phytochemical investigations at Kew by the late Dr. M. Greshoff, Kew Bulletin, No. 10, 1909, p. 405.) In this connection see Brunnich on frothing of the seeds, bottom of p. 149, vol. i, of this work.


Castanospermum australe: Tree in the Botanic Gardens, Sydney. — (Government Printer, photo.)

Supplementary Material Added With Volume 5

No. 24. Part VII. See also vols. ii, p. 197; iv, p. 162.

Castanospermum australe, A. Cunn.



There is an interesting paper entitled "The poisonous effects of the Black Bean (Castanospermum australe) on Cattle," by S.T.D. Symons, M.R.C.V.S., Chief Inspector of Stock, in Agric. Gaz. N.S.W., March 1911, p. 196.

no previous
no next