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 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.[3] 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[5] 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.
- ↑ Kerner, Nat. Hist. of Plants (Eng. trans.) ii. 572.
- ↑ See Lyon's paper in Minnesota Botanical Studies, 1904, p. 275.
- ↑ 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.
- ↑ See Schneider, Dendrologische Winterstudien, 127 (1903), and Max Leichtlin in Woods and Forests, Jan. 16, 1884.
- ↑ Bull. de l'Assoc. des anc. élèv. de lécole d'Hort. de Versailles, 1898, p. 597, quoted in Gard. Chron. 1899, xxv. 201.
