The Trees of Great Britain & Ireland/Volume 1/Ginkgo

by Henry John Elwes and Augustine Henry

 

GINKGO

 

Ginkgo, Linnæus, Mantissa, ii. 313 (1771); Bentham et Hooker, Gen. Pl. iii. 432, 1225 (1880); Masters, Jour. Linn. Soc. (Bot.), xxx. 3 (1893).

Salisburia, Smith, Trans. Linn. Soc. iii. 330 (1797).

 

Trees, several extinct and one living species, bearing fan-shaped, fork-veined leaves on both long and short shoots. Flowers diœcious, arising from the apex of short shoots, which bear at the same time ordinary leaves. Male flowers: catkins, 3–6 on one shoot, each being a pendulous axis bearing numerous stamens loosely arranged. Stamen a short stalk ending in a knob, beneath which are 2–4 divergent anthers, dehiscing longitudinally. Female flowers, 1–3, more or less erect on the shoot, each consisting of a long stalk, which bears an ovule on either side below the apex. The ovule is sessile, straight, surrounded at its base by an aril or collar-like rim,^[1] and naked (i.e. not enclosed in an ovary). Fruit: a drupe-like seed (sessile in the small bowl-shaped little developed aril) consisting of an orange fleshy covering enveloping a woody shell, within which, embedded in the albumen, lies an embryo with 2–3 cotyledons. The albumen is covered by a thin membrane which is only adherent to the woody shell in its lower part. Two embryos often occur in 1 seed, and of the 2 ovules only one is generally developed into a seed.

Ginkgo was formerly considered to belong to the Coniferæ, but recent investigations show that it is distinct from these, and is the type of a Natural order Ginkgoaceæ, which has affinities with Cycads and ferns. The seeds resemble closely those of Cycads, and at the end of the pollen tube are formed two ciliated antherozoids which are morphologically identical with the antherozoids occurring in ferns. Ginkgo, however, is a true flowering plant, as it produces seeds, and is a gymnosperm, since it bears ovules which are not enclosed in an ovary.

The extinct species have been found in the Jurassic and succeeding epochs. Gardner^[2] considers the specimens which have been found in the white clay at Ardtun in the Isle of Mull to be specifically identical with Ginkgo biloba.

 

 

GINKGO BILOBA, Maidenhair Tree

 

Ginkgo biloba, Linnæus, Mantissa, ii. 313 (1771); Kent in Veitch's Man. Coniferæ, 2nd ed. 107 (1900); Seward and Gowan, Ann. Bot. xiv. 109 (1900).

Salisburia adiantifolia, Smith, Trans. Linn. Soc. iii. 330 (1797); Loudon, Arb. et Frut. Brit. iv. 2094 (1838).

 

The Ginkgo when young is pyramidal in habit, with slender, upright branches: older, it becomes much more spreading and broader in the crown. It attains a height of 100 feet and upwards, with a girth of stem of about 30 feet. Bark: grey, somewhat rough, becoming fissured when old.

Leaves: deciduous, scattered on the long shoots, crowded at the apex of the short shoots, which grow slowly from year to year, their older portions being covered with the leaf-scars of former years. The short shoot may, after several years, elongate into a long shoot bearing scattered leaves. The leaves are stalked, and unique in shape amongst trees, recalling on a large scale the pinna of an adiantum fern; they show much variation in size (2–8 inches in breadth) and in margin, but generally are bilobed and irregularly crenate or cut in their upper part. There is no midrib, and the veins, repeatedly forking, are not connected by any cross veinlets. The stomata are scattered on the lower surface. In the bud the leaves are folded together and not rolled up, as in the crozier-like vernation of ferns.

Flowers and fruit: see description of the genus.

The drupe-like seeds have a fleshy outer covering of a bright orange colour when ripe, and when they fall upon the ground, this bursts and emits an odour of butyric acid which is very disagreeable.^[3] They are imperfectly developed as they fall, though apparently ripe; and the fertilisation of the ovule and the subsequent development of the embryo occur while they are lying on the ground during winter. The kernels are edible, being known to the Chinese as pai-kuo (white fruits), and are sold in most market towns of China. They are supposed to promote digestion and diminish the effects of wine-drinking; and are eaten roasted at feasts and weddings, the shells being dyed red.

Fruit-bearing trees are now common in Southern Europe; but no fruit, so far as we know, has ever been produced in England. The well-known tree at Kew is a male, and produces flowers freely in exceptional years, e.g. in 1894, supposed to be due to the fact that the preceding summer was remarkably warm, with continual sunshine.

Extraordinary cases of abnormal formation of fruit have been observed in Japan. Shirai^[4] described and figured in 1891 fruit which was produced on the surface of ordinary leaves of the tree. Fujii has studied since then the various stages of the development of ovules and of pollen sacs upon leaves. The so-called aril of the fruit is considered by him to represent a carpel, as he has observed transitional stages between the ordinarily shaped aril and a leafy blade bearing ovules.

Jacquin^[5] grafted on the male tree at Vienna, when it was quite small, a bud of the female tree, from which a branch developed. This tree is now of large size; and numerous branches regularly bear male flowers, whilst one branch, now very stout, bears female flowers. This female branch puts forth its foliage about fourteen days later than the male branches, and retains them much later in autumn. In this case the shoot retains its individual characters, and the stock does not affect it even in regard to its annual development.

Seedling.—The germination in Ginkgo is not unlike that of the oak. We are indebted to Mr. Lyon^[6] of Minneapolis for figures of the seedling, which are reproduced on Plate 15 c, d.

When the seeds are sown the hard shell is cracked at its micropylar end by the swelling of the embryo within. Through this opening the body of the embryo is thrust out by the elongation of the cotyledons; which remain attached to the caulicle by two arching petioles; between these the plumule or young stem ascends, while the root turns down into the soil. The cotyledons remain attached throughout the first season's growth. The first two or three leaves directly above the cotyledons remain small and scale-like. After reaching 4 or 5 inches in height the stem stops growing, having expanded into a rather close crown of ordinary leaves at its apex, which ends in a large terminal bud. The root attains in the first season about the same length as the stem, and develops numerous lateral fibres. This primary root, as is usually the case in Gymnosperms, persists as the tap-root of the plant.

Sexes.—Certain differences, besides those of the flowers, are observable in male and female trees.^[7] The male trees are pyramidal and upright in habit, the ascending branches being of free and vigorous growth. The female trees are closer and more compact in habit, more richly branched below, and the branches sometime become even pendent.^[8]

Monsieur L. Henry^[9] states that in Paris the leaves of the female Ginkgo fell three or four weeks later than those of the male. Generally male trees are completely denuded of foliage by the beginning of November, while the female trees retain their leaves till the end of November or the beginning of December.

Burrs.—In Japan there often develops on old Ginkgo trees peculiar burrs, which are called chi-chi or nipples. These may be observed in an incipient stage on the large tree at Kew. They occur on the lower side of the larger branches of the tree, and vary in size from a few inches in length to 6 feet long by 1 foot in diameter. They occur singly or in clusters, and are generally elongated, conical in shape, with a rounded tip. If they reach the ground, as is sometimes the case, they take root, and then bear leaves. They are due to the abnormal development of dormant or adventitious buds. A description of this curious phenomenon and a photograph of a tree bearing a large number of these growths is given by Fujii in Tokyo Bot. Mag. 1895, p. 444. We are indebted to Mrs. Archibald Little for a photograph taken by her in Western China, of a tree 19½ feet round the base, and larger above, which very well shows these excrescences (Plate 23).

 

Identification

In summer the leaves are unmistakable. In winter the long and short shoots should be examined. The long shoot of one year's growth is round, smooth, brownish, and shining, the terminal buds being larger than the scattered lateral buds, which come off at a wide angle. The buds are conical, and composed of several imbricated brown dotted scales. The leaf-scars show 2 small cicatrices, and are fringed above with white pubescence. The short shoots are spurs of varying length, up to an inch or more, stout, ringed, and bearing at their apex a bud surrounded by several double-dotted leaf-scars. In Pseudolarix and the larches, which have somewhat similar spurs, the leaf-scars are much smaller, and show on their surface only one tiny cicatrice. In Taxodium there are no spurs, and the scars which are left where the twigs have fallen off show only one central cicatrice.

 

Varieties

The following forms are known in cultivation:—

Var. variegata. Leaves blotched and streaked with pale yellow.

Var. pendula. Branches more or less pendulous.

Var. macrophylla laciniata. Leaves much larger than in the ordinary form, 8 inches or more in width, and divided into 3 to 5 lobes, which are themselves subdivided.

Var. triloba. Scarce worthy of recognition, as the leaves in all Ginkgo trees are exceedingly variable in lobing.

Var. fastigiata. Columnar in shape, the branches being directed almost vertically upwards.^[10]

 

Distribution and History

The wild habitat of Ginkgo biloba, the only species now living, is not known for certain. The late Mrs. Bishop, in a letter to the Standard, Aug. 17, 1899, reported that she had observed it growing wild in Japan, in the great forest northward from Lebungd on Volcano Bay in Yezo, and also in the country at the sources of the great Gold and Min rivers in Western China. However, all scientific travellers in Japan and the leading Japanese botanists and foresters deny its being indigenous in any part of Japan; and botanical collectors have not observed it truly wild in China. Consul-General Hosie^[11] says it is common in Szechuan, especially in the hills bounding the upper waters of the river Min; but he does not explicitly assert that it is wild there. Its native habitat has yet to be discovered; and I would suggest the provinces of Hunan, Chekiang, and Anhwei in China as likely to contain it in their as yet unexplored mountain forests.

The earliest mention of the tree in Chinese literature occurs in the Chung Shu Shu, a work on agriculture, which dates from the 8th century, a.d. The author of the great Chinese herbal (Pen-Tsao-Kang-Mu, 1578 a.d) does not cite any previous writers, but mentions that it occurs in Kiangnan (the territory south of the Yangtse), and is called Ya-chio-tze, "duck's foot," on account of the shape of the leaves. At the beginning of the Sung dynasty (1000 a.d), the fruit was taken as tribute, and was then called Yin-hsing, "silver apricot," from its resemblance to a small apricot with a white kernel. In the Chih-Wu-Ming, xxxi. 27, there is a good figure of the foliage and fruit; and the statement is made that in order to obtain fruit the tree should be planted on the sides of ponds.

At present it occurs planted in the vicinity of temples in China, Japan, and Corea. It has always been the custom of the Chinese to preserve portions of the natural forest around their temples; and in this way many indigenous species have been preserved that otherwise would have perished with the spread of agriculture and the destruction of the forests for firewood and timber, in all districts traversed by waterways. Most of the curious conifers in China and Japan have a very limited distribution, and Ginkgo is probably no exception; though it is possible that it may still exist in the region indicated above.

I have never seen any remarkable specimens in China; but Bunge^[12] says that he saw one at Peking, of prodigious height and 40 feet in circumference.

In Japan Elwes says that it is planted occasionally in temple courts, gardens, and parks. He did not see any very large specimen of the tree, the best being one in the court of the Nishi Hongagi temple at Kioto, which was of no great height, but had a bole about 15 feet in girth at 3 feet, where it divided into many widespreading branches which covered an area of 90 paces in circumference. This tree had green leaves and buds on the old wood of the trunk close to the ground, which he did not notice in other places.

Rein^[13] says that the largest he knew of is at the temple of Kozenji near Tokyo, and this in 1884 was 7.55 metres in girth, and according to Lehman about 32 metres high. There is also one in the Shiba park, which in 1874 was 6.30 metres in girth. The tree is sometimes grown in a dwarf state in pots, but does not seem to be a favourite in Japan. The wood is somewhat like that of maple in grain, of a yellowish colour, fine grained, but not especially valued, though it is used for making chess boards and chessmen, chopping blocks, and as a groundwork for lacquer ware. The nuts are sometimes eaten boiled or roasted, but are not much thought of.

Ginkgo was first made known to Europeans by Kaempfer,^[14] who discovered it in Japan in 1690, and published in 1712 a description with a good figure of the foliage and fruit. Pallas^[15] visited the market town of Mai-mai-cheng, opposite Kiachta, in 1772, and saw there Ginkgo fruit for sale which had been brought from Peking. Fortune^[16] mentions that the tree grows to a very large size in the Shanghai district, and in the northern part of the Chekiang province. The Japanese name Ginkgo is their pronunciation of the Chinese yin-kuo, "silver fruit"; but the common name in Japan is i-cho.

 

Introduction

The tree was introduced into Europe about 1730, being first planted in the Botanic Garden at Utrecht. Jacquin brought it into the Botanic Garden at Vienna sometime after 1768. It was introduced into England about 1754; and into the Unites States in 1784, by W. Hamilton, who planted it in his garden at Woodlawn, near Philadelphia. It first flowered in Europe at Kew in 1795. Female flowers were first noticed by De Candolle in 1814 on a tree at Bourdigny near Geneva. Scions of this tree were grafted on a male tree in the Botanic Garden of Montpellier; and perfect fruit was produced by it for the first time in Europe in 1835.

 

Cultivation

Ginkgo is easily raised from seeds, which retain their vitality for some months. Female plants may be obtained by grafting. It is easily transplanted, even when of a large size. Trees of over 40 feet high have been successfully moved. It thrives in deep, well-drained, rich soil. It is useful for planting in towns, as it is free from the attacks of insects and fungi; and the hard leathery leaves resist the smoke of cities. It may also be freely pruned. It is of course best propagated by seed; but layers and cuttings may be employed in certain cases. Falconer (loc. cit.) says that it is not readily propagated by cuttings, and that it took two years to root a cutting in the gardens at Glen Core (U.S.A.). Pyramidal forms can be obtained by careful selection, and the broad-leaved variety by careful grafting. The Ginkgo is well adapted for cultivation in tubs or vases, and may then be trained either as a pyramid or a bush.

The tree has a formal appearance when young, and is not really beautiful till it attains a fair age. The peculiar form of the leaves renders it a striking object. The foliage, just before it falls in autumn, turns a bright yellow^[17] colour, which makes it very effective in that season, but only for a few days, as the defoliation is very rapid.

 

Remarkable Trees

Ginkgo is perfectly hardy in England, and, as a lawn tree, is seen to great advantage. Many trees of considerable size occur in different parts of the country. The best known one is that at Kew, of which a photograph is given (Plate 21). In 1888 it was (measured by Mr. Nicholson) 56 feet in height, with a girth of 9 feet at a yard from the ground. It has a double stem, and in 1904 had increased to 62 feet high by 10 feet 4 inches in girth. Other remarkable trees near London^[18] are:—

One at Chiswick House, which measured in 1889, 57 feet by 6½ feet, and in 1903, 62 feet by 6 feet 11 inches; and another at Cutbush's Nursery, Highgate, which was in 1903 56 feet high by 4½ feet in girth.

Ginkgo trees may be seen in the following places in London:—Victoria Park, Telegraph Hill, Lincoln's Inn Fields, Waterlow Park, Southwark Park.

At Grove Park, Herts, a tree measured in 1904 68 feet high by 8 feet 5 inches in girth.

At Bank House, Wisbech, the residence of Alexander Peckover, Esq., there is a tree which was 65 feet high and 7 feet in girth in 1904.

There is a very fine tree^[19] at Frogmore, Windsor, which in 1904 measured 74 feet by 9 feet 3 inches, but divides into four stems (Plate 22).

At Barton, Suffolk, a tree planted in 1825 measured in 1904 50 feet by 2 feet 5 inches.

At Sherborne, Dorset, a tree 70 feet by 7 feet 7 inches in 1884.

At Melbury, Dorchester, the tallest tree in England is said to occur, being stated to be over 80 feet in height.^[20] The tree at Panshanger^[20] is reported to be 70 feet high by 10 feet at 1 foot above the ground. At Longleat^[20] there is a tree 71 feet by 9½ feet girth at 1 foot above the soil.

At Cobham Park, Kent, a tree 68 feet by 9 feet 4 inches.

At Badminton, Gloucestershire, a pair of symmetrical trees each about 50 feet by 5 feet.

At Blaize Castle, near Bristol, there is a good tree, of which Lord Ducie has kindly sent a photograph and a letter from Miss Harford, dated December 1903, which states:—"The Salisburia is, I am glad to say, in perfect condition, and a very fine graceful tree. Its height, measured last summer, was 72 feet. I have always heard that the one at Kew (which is not nearly so well grown) and the one in the Bishop's garden at Wells came over from Japan in the same ship as our tree."^[21]

In Wales the finest tree that we know of is at Margam Park, Glamorganshire, the residence of Miss Talbot, which in 1904 was about 70 feet high and 6 feet in girth.

We have not heard of any fine specimens in Scotland or Ireland.

A curious form of the Ginkgo tree is reported^[22] to occur at Cookham Grove, Berkshire. This tree grows within 10 feet of the river wall, which surrounds the lawn, and when there is high water the roots are under water for several days at a time. The bole is only 2 feet in height, but measures 4½ feet in girth; at that point it breaks into many branches, some going upright to a distance of over 30 feet, while others grow almost horizontally, the spread of the branches being 45 feet.

Much finer trees occur on the Continent than those in England; and it is evident that while the tree is healthy and hardy in this country, it requires hotter summers and colder winters to attain its best development and ripen fruit. A fine pair, male and female, stand in the old Botanic Garden of Geneva, where they were planted in 1815. They were measured by Elwes in 1905, when the male tree was 86 feet by 4 feet 10 inches, with a straight upright habit, the female, which bears good seed, was considerably smaller. A famous specimen in the garden adjoining the palace of the Grand Duke of Baden at Carlsruhe measured, in 1884, 84 feet, with a diameter of 25 inches at 3 feet from the ground. Beissner^[23] says trees occur in this garden of 25½ and 30 metres high, with stem diameters of 1.90 and 1.80 metres. The finest tree in Europe is probably one mentioned by Beissner,^[23] which stands in the Botanic Garden at Milan, and measures 40 metres high and 1.20 metre in diameter. There is also a noble specimen in the gardens of the Villa Carlotta on Lake Como. (A.H.)

 

1. Considered now to be a reduced carpel.
2. J. S. Gardner, British Eocene Flora (1886), ii. 100.
3. "The pulp surrounding the seed has a most abominable odour. Although warned not to touch it, I gathered the seeds with my own hands; but it took me two days' washing to get the odour off."—(W. Falconer in Garden, 1890, xxxviii. 602.)
4. Shirai, in Tokyo Bot. Mag. 1891, p. 342.
5. Kerner, Nat. Hist. of Plants (Eng. trans.) ii. 572.
6. See Lyon's paper in Minnesota Botanical Studies, 1904, p. 275.
7. Sargent denies this, and says it is impossible to distinguish the sexes till the trees flower; but observations on the Continent go to show that the sexual differences pointed out above really exist. See Sargent, Garden and Forest, 1890, p. 549.
8. See Schneider, Dendrologische Winterstudien, 127 (1903), and Max Leichtlin in Woods and Forests, Jan. 16, 1884.
9. Bull. de l'Assoc. des anc. élèv. de l'école d'Hort. de Versailles, 1898, p. 597, quoted in Gard. Chron. 1899, xxv. 201.
10. See Garden, 1890, xxxviii. 602. An interesting article by W. Falconer, who gives some curious details concerning the Ginkgo tree in the United States.
11. Parliamentary Papers, China, No. 5, 1904; Consul-General Hosie's Report, 18. Mr. E.H. Wilson in all his explorations of Western China never saw any but cultivated trees.
12. Bunge, in Bull. Soc. d'Agric. du Depart. de l'Herault, 1833.
13. Rein, Industries of Japan.
14. Kaempfer, Amœnitates Exoticæ, 811.
15. Pallas, Reisen durch versch. Provinzen des Russischen Reiches, 1768–1773, vol. iii.
16. See Fortune, Wanderings in China, 118, 251; Residence among the Chinese, 140, 348, 363; Yedo and Peking, 59.
17. There is no trace of red in the autumnal tint, as is usual in other trees in their leaves before they fall. The tint in Ginkgo depends entirely on the yellow coloration of the disorganised chlorophyll corpuscles, and forms a beautiful object for the microscope.
18. The well-known trees in the Chelsea Botanic Garden and in High Street, Brentford, are now mere wrecks.
19. Figured in Garden, 1904, lxvi. 344.
20. Flora and Sylva, ii. (1904), p. 357.
21. Elwes has since seen and measured this tree, which he made to be 68 feet by 9 feet 3 inches, with a bole about 12 feet high.
22. Gard. Chron. 1886, xxv. 53.
23. Beissner, Nadelholzkunde, 1891, pp. 191, 192. One of the trees at Carlsruhe is figured in Gartenwelt, iv. 44, p. 520.