Vegetable Teratology. Maxwell T. Masters
entirely to those peculiarities which, by an unhappy application of words, are called monstrous by botanists. Grafting, layering, the "striking" of cuttings, the formation of adventitious roots and buds, processes on which the cultivator so greatly relies for the propagation and extension of his plants, are also matters with which teratology concerns itself. Again the difficulty experienced occasionally in getting vines, strawberries, &c., to set properly, may sometimes be accounted for by that inherent tendency which some plants possess of exchanging an hermaphrodite for a unisexual condition.
For reasons then of direct practical utility, no[Pg xxxviii] less than on purely scientific grounds, it is desirable to study these irregularities of growth, their nature, limits, and inducing causes; and to this end it is hoped the present work may, in some degree, contribute.
FOOTNOTES:
[1] An excellent summary of the history of Vegetable Teratology is given in Kirschleger's 'Essai historique de la Tératologie Végétale,' Strasburg, 1845.
[2] In some instances diagrams and formulæ are given in explanation of the conformation of monstrous flowers; in general these require no further explanation than is given in the text, unless it be to state that the horizontal line—is intended to indicate the cohesion of the parts over which it is placed, while the vertical line | signifies the adhesion of the organs by whose side it is placed. The formula
S S S S S
------------------------
| P P P P P
|
| ST ST ST ST ST
shows that the sepals (S) are distinct, the petals (P) coherent, and the stamens (ST) adherent to the petals.
[3] Wolff was the first to call attention to the great importance of the study of development. He was followed by Turpin, Mirbel, Schleiden, Payer, and others, and its value is now fully recognised by botanists.
[4] Agardh, "Theoria Syst. Plant.," p. xxiii.
[5] In the memoirs of Hopkirk, Kirschleger, Cramer, Hallier, and others, malformations are arranged primarily according to the organs affected, an arrangement which has only convenience to justify it. It is hoped that the index and the headings to the paragraphs in the present volume will suit the convenience of the reader as well as if the more artificial plan just alluded to had been adopted.
[6] Cryptogamous plants are only incidentally alluded to in these pages, owing to their wide difference in structure from flowering plants. Attention may, also, here be called to a paper of M. de Seynes in a recent number of the Bulletin of the Botanical Society of France, vol. xiv, p. 290, tab. 5 et 6, in which numerous cases of malformation among agarics are recorded. See also same publication, vol. iv, p. 744; vol. v, p. 211; vol. vi, p. 496.
[7] On this subject see a paper of M. Naudin in the 'Comptes Rendus,' 1867, t. 64, pp. 929–933.
[8] It is probable that many terms and expressions calculated to mislead in the way above mentioned are made use of in the following pages. The inconsistency manifested by their use may be excused on the ground of ignorance of the true structure, and by the circumstance that in many cases facts alone are recorded without an explanation of them being offered. Moreover, it is desirable to act in conformity with the usual practice of botanical writers, and not to change established terminology, even if suspected to convey false ideas, until the true condition of affairs be thoroughly well ascertained by organogenetic research or other means.
[9] A curious illustration of the latter class of alterations came under the writer's notice last summer (1868), and which he has reason to believe has not been previously recorded, viz. the persistence in an unwithered state of the petals at the base of the ripe fruit, in a strawberry. All the fruits on the particular plants alluded to were thus provided as it were with a white frill. Whether this be a constant occurrence in the particular variety is not known.
VEGETABLE TERATOLOGY.
BOOK I.
DEVIATIONS FROM THE ORDINARY ARRANGEMENT OF ORGANS.
As full details relating to the disposition or arrangement of the general organs of flowering plants are given in all the ordinary text-books, it is only necessary in this place to allude to the main facts at present known, and which serve as the standard of comparison with which all morphological changes are compared.
Even in the case of the roots, which appear to be very irregular in their ramification, it has been found that, in the first instance at least, the rootlets or fibrils are arranged in regular order one over another, in a certain determinate number of vertical ranks, generally either in two or in four, sometimes in three or in five series. This regularity of arrangement (Rhizotaxy), first carefully studied by M. Clos, is connected with the disposition of the fibro-vascular bundles in the body of the root. This primitive regularity is soon lost as the plant grows.
In the case of the leaves there are two principal modes of arrangement, dependent, as it would seem, on their simultaneous or on their successive development; thus, if two leaves on opposite sides of the stem are developed at the same time, we have the arrangement called opposite; if there are more than two, the disposition is then called verticillate or whorled. On the other hand, if the leaves are developed in succession, one after the other, they are found to emerge from the stem in a spiral direction. In either case the leaves are arranged in a certain regular manner, according to what are called the laws of Phyllotaxis, which need not be entered into fully here; but in order the better to estimate the teratological changes which take place, it may be well to allude to the following circumstances relating to the alternation of parts. The effect of this alternation is such, that no two adjacent leaves stand directly over or in front one of the other, but a little to one side or a little higher up. Now, in the alternate arrangement the successive leaves of each spiral cycle alternate one with another till the coil is completed. For the sake of clearness this may be illustrated thus:—Suppose the spiral cycle to comprise five leaves, numbered 1, 2, 3, 4, 5, then 2 would intervene between 1 and 3, and so on, while the sixth leaf would be the commencement of a new series, and would be placed exactly over 1. This arrangement may be thus formularised:
6 7 8 9 10
1 2 3 4 5
In the verticillate or simultaneous arrangement of leaves the case is somewhat different. Let us suppose a whorl of eight leaves, surmounted by a similar whorl of eight. In such a case it will generally be found that the whorls alternate one with another, as may be represented by this symbol:
9 10 11 12 13 14 15 16
1 2 3 4 5 6 7 8
The simplest illustration of this arrangement is seen in the case of decussate leaves, where those organs are placed in pairs, and the pairs cross one another at right angles.