The Trees of Great Britain & Ireland/Volume 2/Gymnocladus

by Henry John Elwes and Augustine Henry

 

GYMNOCLADUS

 

Gymnocladus, Lamarck, Dict. i. 773 (ex parte) (1783); Bentham et Hooker, Gen. Pl. i. 568 (1865).

Guilandina, Linnæus, Gen. Pl. 518 (ex parte) (1742).

 

Deciduous trees, belonging to the division Cæsalpinieæ of the order Leguminosæ. Branches stout and without thorns. Leaves large, alternate, bipinnate, the number of pinne being either odd or even; pinnæ and leaflets usually alternate. Stipules foliaceous, early deciduous.

Flowers polygamous or diœcious, terminal or axillary, in racemes or racemose corymbs, on long pedicels. Calyx tubular, lined with a glandular disc, ten-ribbed, five-lobed, the lobes narrow and nearly equal. Petals four to five, slightly unequal, imbricated, inserted on the. margin of the disc, spreading. Stamens ten, free, shorter than the petals and inserted with them, those opposite the calyx lobes longer than the others; anthers oblong. Ovary rudimentary or absent in the staminate flowers, sessile or sub-sessile in the polygamous and pistillate flowers; style short and dilated above obliquely into a two-lobed stigma.^[1] Ovules four or numerous.

Pod oblong, thick, coriaceous, dark brown, flattened, beaked at the apex, slightly curved or falcate, on stalks ½ to 2 inches long, pulpy between the seeds. Valves two, narrowly winged on the margins. Seeds on long slender stalklets; seed-coat thick and bony; embryo surrounded by a layer of horny albumen.

Only two species are known, one occurring in China and doubtfully hardy in this country, the other a native of N. America and cultivated in England.

 

GYMNOCLADUS CHINENSIS, Chinese Soap Tree

 

Gymnocladus chinensis, Baillon, Compt. Rend. Assoc. Franç. Avanc. Sc. 1874, p. 418, t. 4, and Bull. Soc. Linn. Paris, 1875, p. 33; Oliver, in Hooker, Icon. Plant. xv. 9, t. 1412 (1883); Hemsley, Journ. Linn. Soc (Bot.) xxiii. 207 (1887).

Dialium sp.?, Hanbury, Science Papers, 238, fig. 5 (1876).

 

A tree attaining 40 feet in height. Young shoots rusty pubescent. Leaves 1 to 3 feet long; pinnæ alternate or sub-opposite, all composed of numerous (twenty to twenty-four) leaflets, which are ¾ to 1½ inch long, alternate, oblong, rounded at the base, obtuse or rarely acute at the apex, densely silky appressed pubescent beneath, on short pubescent petiolules; rachis densely pubescent, swollen at the base, and forming a conical sheath enclosing the bud.

Flowers polygamous, in pubescent racemes, those with staminate flowers shorter than the others. Calyx pubescent, with subulate lobes. Petals oval-oblong. Ovary glabrous with four ovules. Pod, 4 inches long by 1½ inch broad, glabrous. Seeds, two to four, black, globose, smooth, ¾ inch in diameter.

This tree is rather rare in China, though specimens have been collected in the provinces of Anhwei, Kiangsi, Chekiang, Hupeh, and Szechuan. Near Ichang it grows at 1000 to 2000 feet altitude. The pods, called fei-tsao, after being steeped in water, produce a liquid esteemed for washing the hair and cleansing silk articles.

Plants^[2] were raised at Kew from seeds sent by me in 1888; but died in a year or two. Seeds, which could be easily procured from Shanghai, where they are sold in the shops, might be tried in the warmer parts of England and Ireland, as the tree is worth cultivating on account of its beautiful delicate foliage. (A.H.)

 

GYMNOCLADUS CANADENSIS, Kentucky Coffee Tree

 

Gymnocladus canadensis, Lamarck, Encycl. i. 733 (1783); Loudon, Arb. et Frut. Brit. ii, 656 (1838).

Gymnocladus dioicus, Koch, Dendrologie, i. 5 (1869); Sargent, Silva N. Amer. iii. 69, tt. 123, 124 (1892), and Trees N. Amer. 554 (1905).

Guilandina dioicus, Linnæus, Sp. Pl. 381 (1753).

 

A tree attaining in America over 100 feet in height and 9 feet in girth. Bark fissured, dark grey, and roughened by small persistent scales. Young shoots covered with short pubescence. Leaves (Plate 125, fig. 4) 1 to 3 feet long, with 5 to 11 pinnæ, which are usually alternate but occasionally sub-opposite, the two or rarely the four lower pinnæ simple, the others composed of six to fourteen alternate pinnate leaflets. Leaflets 2 to 3 inches long, on pubescent stalklets, ovate, rounded at the base, acuminate at the apex, entire and ciliate in margin; under surface with scattered long hairs.

Flowers usually diœcious, the inflorescence of the staminate tree a short racemose corymb, that of the pistillate tree a long raceme. Calyx tomentose, with five narrow oblong lobes. Petals five, tomentose, longer and broader than the calyx-lobes. Ovary pubescent; ovules ten or more.

Pod, 6 to 10 inches long by 1½ to 2 inches broad, minutely pubescent. Seeds, five to ten, surrounded by dark-coloured sweet pulp, ovoid, ¾ inch long, and covered by a hard dark brown shell.

In the young leaf^[3] of Gymnocladus canadensis, the rachis is prolonged an inch or more above the insertion of the upper pinnæ; and the axes of the pinnæ are similarly prolonged beyond the leaflets. These terminal appendages are very slender and tendril-like, and disappear before the leaf attains its full size. They have been supposed to be rudimentary tendrils, such as occur normally in a developed state in many leguminous plants; but they may represent simply degenerate terminal leaflets.

Sargent states that this species is diœcious; and that in order to obtain fruit male and female trees must be close together. C.M. Hovey,^[4] however, writing from Boston, states that he knows a solitary tree, no other being within two miles, which produces fruit and fertile seeds, from which he has raised many plants. The so-called pistillate flowers have stamens, which doubtless are usually not fully developed; but it is possible that in some cases they may produce good pollen.

The flowers^[5] in America are visited by bees, which are attracted by the nectar secreted by the inner wall of the calyx tube.

 

Identification

In summer the foliage of the tree is unmistakable. In winter the fewness of the branches and the stoutness of the branchlets, which are very short in adult trees, are remarkable. The latter show the following characters:—

Twigs coarse, grey, glabrous, with numerous small brown lenticels and wide, circular, orange-coloured pith. Leaf-scars large, obcordate, slightly oblique on prominent pulvini, with a narrow raised yellowish margin and a whitish convex surface, marked by three to five irregular tubercles, which are the scars of the vascular bundles. Buds very small; two to three vertically superposed, in the axil of each leaf-scar, the lower one rarely developing; projecting slightly out of circular depressions in the bark, which form pubescent rings around the buds. Each bud shows two to three minute scales, which become accrescent and green in the spring at the base of the shoots. No true terminal bud is developed, the tip of the branchlet falling off in summer and leaving at the apex of the twig a circular scar.

 

Distribution

The Kentucky Coffee tree, though occupying a wide area in North America, is nowhere common. It is found scattered amongst other trees on hillsides where the soil is rich, and in alluvial land beside rivers. It is met with in central New York and western Pennsylvania, through southern Ontario and southern Michigan to the valley of the Minnesota River and to eastern Nebraska, eastern Kansas, south-west Arkansas, the Indian territory, and central Tennessee.

The tree is noted^[6] in America for its habit of suckering from the roots when it is cut down. After a tree is felled the ground around to a distance of often 100 feet becomes filled with numerous suckers; and this is one of the ways in which the trees are reproduced in the American forests. The tree never develops any epicormic branches, and is very seldom attacked by any insect or fungus. (A.H.)

An article by Sargent in Garden and Forest, ii. p. 75, gives an excellent account of this tree, and states that by far the largest and handsomest that he has seen was planted in 1804 directly in front of the historical Verplanck mansion at Fishkill-on-Hudson, and was, in 1889, 75 feet high and a little over 10 feet in girth below the point where it divides into three stems at 3 feet from the ground. Though it was struck by lightning in 1887, the tree is an extremely graceful and well-shaped one, as the picture shows.

The tree grows well as far north as Ottawa, where I saw two spreading trees about 4o feet high, planted in front of Rideau Hall, the residence of the Governor-General. The gardener informed me that they were the latest trees to come into leaf, and, though they flowered in good seasons, produced no fruit.

At Mount Carmel, Illinois, I measured a tree in the forest 92 feet by 8 feet, one of the few remaining relics of the splendid trees described by Ridgway, one of which was 109 feet high, with a clear stem 76 feet to the first limb, but only 20 inches across the stump. Dr. Schneck has measured one in the same locality no less than 129 feet high. It is, however, nowhere an abundant tree in this district, but grows scattered through the richer bottoms.

The tree from which a specimen log in the Jessup collection in the American Museum of Natural History was cut, grew not far from St. Louis, and although only 18 inches in diameter was 105 years old. This represents the average rate

of increase of the tree growing naturally in the forest, cultivated trees in favourable conditions growing much more rapidly.

 

Cultivation

Gymnocladus canadensis was introduced into England by Archibald, Duke of Argyll, who had a tree in cultivation^[7] at Whitton in 1748. This tree was afterwards removed to Kew, on the establishment of the gardens there by the Princess of Wales, mother of George III., who obtained it and many other interesting trees as a present from the Duke of Argyll in 1762. This tree died^[8] about 1870; and as old trees reported by Loudon at Syon and elsewhere cannot now be found, it goes to show that the tree lives little over 100 years in England.

 

 

Plate 120: Gymnocladus (canadensis) at Claremont

Plate 120.

GYMNOCLADUS AT CLAREMONT

 

According to Nicholson,^[9] it is very easy to transplant, and bears drought well. It is propagated either by seeds or by root-cuttings. Pieces of the roots, 4 to 5 inches long, placed in prepared beds and kept moist, will develop in the first year into plants three or four feet high. Some of the cuttings, however, will not start into growth until the following year.

I have raised seedlings from American seeds, which, being large and hard, should be soaked in warm water for some days before sowing. The seedlings grow slowly, and should be kept under glass for a year or two before planting out.

In spite of Loudon's assertion to the contrary, it appears to flower very rarely in England, the only record being at Claremont, where Mr. Burrell^[10] says it produces flowers freely early in summer. Pods have never been produced, so far as we know, in this country.

It is a rare tree in cultivation; but though stiff and peculiar in habit, it is not at all ungainly when well-grown, even when bare of leaves. It comes into leaf very late in the season, and it drops its leaves early in autumn, the stalks, however, often remaining on the tree for weeks. The foliage, like that of many leguminous plants, shows the phenomenon of sleep, the leaflets drooping and closing together soon after sunset in summer.

 

Remarkable Trees

There are two trees at Claremont, which were about 55 feet high in 1888. When I measured them in 1907 the largest was 60 feet by 6 feet 7 inches, and seemed quite healthy; the other was broken.

A tree at Chiswick House measured, in 1903, 53 feet high by 3½ feet in girth. Another at Barton, Suffolk, was in 1904 57 feet high by 5 feet 2 inches in girth at two feet from the ground, and divided above this into two stems. In the Botanic Garden at Cambridge there is a good specimen, which was 45 feet by 3 feet 9 inches in 1906. There are three smaller trees in the Oxford Botanic Garden.

At Kayhough, Kew, in the garden of Mr. Charles Wright, there is a healthy and well-shaped tree, which was in November 1905, 40 feet high by 2 feet 9 inches in girth, with a bole of 6 feet, dividing into two main stems. This tree was purchased from a nurseryman at Kingston in 1878, when it was said to be twentytwo years old, and was then about two-thirds its present height. After transplanting, it made no growth for three years; but since then it has grown steadily though very slowly, and has not been injured in any way by severe winters, though it has never flowered. It has been much surpassed in rate of growth by an Ailanthus in the same garden. There is a tree of about the same size growing close to Mr. Clarke's house at Andover, Hants, which is fifty to sixty years old and measures 43 feet by 2 feet 10 inches. There are several small trees in Kew Gardens, the largest one being near the main entrance.

It seems evident that the tree, to attain a large size, requires a much greater degree of summer heat than it gets in England, for in the south of France it becomes a splendid tree. I saw in the Museum Gardens at Chambery, in the grounds of the Castle formerly belonging to the Dukes of Savoy, a tree which, though forked near the ground, had two tall clean trunks each about 100 feet by 5 to 6 feet. The leaves were only just appearing on 18th May, and many of the large bean-like pods full of greenish pulp, which had fallen in the winter, lay on the ground. Seeds from these pods germinated, but the seedlings, with one exception, withered soon afterwards. It is not uncommon in Savoy, and I saw a fine specimen, 81 feet by 9 feet 6 inches, in the Public Gardens at Aix-les-Bains, which in October 1906 had ripe pods on it. It is known in France by the name of “Bonduc.”

In the old Botanic Garden at Padua a splendid tree was in 1895, according to Prof. Saccardo,^[11] 135 years old, 21 metres high, and 2.60 metres in girth, When I saw it in 1905 the trunk was broken off at about 12 feet, but long shoots, which were in flower, had been produced from the stump. (H.J.E.)

 

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1. The stigma of Gymnocladus chinensis is not correctly shown in Hook. Ic. Pl. t. 1412.
2. Cf. Nicholson, Garden and Forest, 1889, p. 139.
3. Cf. B.D. Halstead, in Torreya, ii. 5 (1902).
4. Garden, xiv. 240 (1878).
5. Robertson, Trans. Acad, Sc. St. Louis, vii. 165 (1897).
6. Garden and Forest, vii. 358 (1894).
7. Aiton, Hort. Kew. v. 400 (1813).
8. J. Smith, Dict. Econ. Plants, 235 (1882), mentions this tree as if it was still living in 1882; but according to Nicholson it had died several years previously to that date.
9. Garden, xxiv. 29 (1883).
10. Garden, xxxiii. 229 (1888) and xlv. 404 (1894).
11. L'Orto Botanico di Padova (1895).