Monstrosities - Teratology - Atrophy of organs - Shanking of grapes - Barren fruit trees - Dwarfing - Distortions and malformations - Fasciations - Flattened roots - Torsions - Curling and puckering - Leaf rolling - So-called "spontaneous " teratological changes.
Monstrosities. - In a wide sense this term is applicable to many cases here treated under other headings, and signifies any departure from the normal standard of size, form, arrangement, or number of parts, and so forth, due to arrest of growth, excessive growth of parts, or of the whole organs, etc.
Such teratological conditions are however by no means always pathological: that is to say, they may be variations which do not threaten the existence of the plant. In some cases they are clearly due to exuberant nutrition, and although they may occasionally predispose to disease, in others they show no evidence of doing so. The whole practice of horticulture and agriculture abounds in examples of teratological sports or varieties which are transmissible by seeds, budding and grafting, and other means - e.g. double flowers, hypertrophied floral organs (cauliflowers), seedless grapes and oranges, crested ferns, etc.; and even when such varieties could not live as such in a state of nature, there is evidence to show that many of them readily revert to the original seed-bearing or single condition, and adapt themselves to the altered environment.
Every part of the plant may exhibit teratological changes, and I shall for the most part select cases in illustration which indicate approach to pathological states, and group with them cases known to be pathological in origin.
For the details and classification of the multitude of facts, the student is referred to Masters' Vegetable Teratology, Ray Society, 1869, and the pages of the Gardeners' Chronicle since that date.
Concerning torsions, etc., the student should read De Vries, "On Biastrepsis in its Relation to Cultivation," Ann. of Bot., Vol. XIII., 1899, p. 395, and " Hybridising of Monstrosities," Hybrid Conference Report, Roy. Hort. Soc., 1900, Vol. XXIV., p. 69.
The reader will find an excellent account of the abnormalities in flowers due to the action of parasitic insects and fungi in Molliard, " Cecidies Florales," Ann. des Sc. Nat., Ser. VIII., Bot., T. 1, 1895, p. 67.