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56 The Trees of Great Britain and Ireland
GINKGO BILOBA, MAIDENHAIR TREE
Ginkgo biloba, Linnaeus, Mantissa, ii. 313 (1771); Kent in VeitcKs Man. Coniferce, 2 nd ed. 107
(1900); Seward and Gowan, Ann. Bot. xiv. 109 (igoo).
Salisburia adiantifolia, Smith, Trans. Linn. Soc. iii. 330 (1797); Loudon, Arb. et Frttt.
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. 1 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 zs 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 2 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.
1 " 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, 1 890, xxxviii. 602.)
2 Shirai, in Tokyo Bot. Mag. 1 891, p. 342.
Ginkgo 57
Jacquin 1 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 2 of Minneapolis for figures of the seedling, which are repro
duced on Plate 15 c, D.
f 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. 8 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. 4
Monsieur L. Henry 6 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 i 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 adven
titious 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.
1 Kerner, Nat. Hist, of Plants (Eng. trans.) ii. 572.
2 See Lyon's paper in Minnesota Botanical Studies, 1904, p. 275.
3 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, 1 890, p. 549.
4 See Schneider, Dendrologische Winterstudien, 1 27 (1903), and Max Leichtlin in Woods and Forests, Jan. 16, 1884.
6 Bull, de I'Assoc. des am. (lev. de F4cole d'Hort. de Versailles, 1898, p. 597, quoted in Card. Chron. 1 899, xxv. 201.