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The synonymes of plants are the names applied to particular species by different authors. Names are often unlike each other; in which case synonymes become indispensable to a right knowledge of a plant; but when one name only has been given by common consent, synonymes, in that case, are of less importance. The objects that they serve are these: they indicate — 1. The names of the authors who have described the spe
cies, and the place in their writings in which the descrip
tion is to be found. 2. The chronology of the species, pointing out the period
at which it was first made known to the world. 3. The works in which figures are to be found. 4. The various names under which it has, from time to
time, been known. Synonymes, therefore, if complete, present a brief, but very instructive, history of a plant. In monographs, or complete accounts of particular groups of plants, no synonymes of any importance whatever ought to be omitted: in more concise works, one or two of the principal are sufficient. The importance of a synonyme depends upon its being that of some author who has written, in an original manner, upon a given plant. In proportion as originality decreases, the value of synonymes decreases also.
In arranging synonymes, a strict chronological order should be maintained, beginning with the most ancient name, and ending with the most recent. But, although the citation of the names must be strictly chronological, it does not therefore follow that the quotation of the works in which the names occur should be chronological also : this would lead to great confusion and inconvenience. It has been found practically
better to arrange the names chronologically; and to arrange under each name, in chronological order, those authors who have spoken of the plant by such name.
This will be more apparent from the following example, from the Systema Naturale of De Candolle, in which the dates of the authors' works are introduced to demonstrate the chronological order of their quotations. In practice the dates are usually omitted: it would be, perhaps, an improvement if they were always added.
TROLLIUS ASIATICUS. Helleborus aconiti folio flore globoso croceo. Amm. ruth.
p. 76. n. 101. (1739.) Trollius asiaticus. Lin.! sp. pl. 782 (exclus. Buxb. et Tourn.
syn.) (1763.) — Mill. dict. n. 2. (1768.) - Gmel. fl. sib. 4.
(1799.) — Poir.! dict. 8. p. 122. (1808.)
In order to show distinctly the different value of these synonymes, De Candolle marks with an asterisk (*) those in which good original descriptions are to be found; and to explain which have been ascertained by the actual inspection of authentic specimens, he marks such names with a note of admiration immediately succeeding the name of the author: thus, Lin.! sp. pl. 427. would mean that the original specimen from which the plant was described by Linnæus in the Species Plantarum, page 427., had been actually examined by himself; whereas, if the note of admiration had been omitted, it would have appeared that the only evidence, with respect to the plant described by Linnæus, was obtained from his book itself. This distinction is of great importance, as it shows upon which synonymes implicit reliance can be placed, and to which we can turn with less confidence.
In proportion to the importance of synonymes ought to be the care with which they are quoted. No synonymes ought to be adopted by a writer, upon the credit of others; he should always judge for himself; or, if that should not be in his power, he should take care to show which have been ascertained by himself, and for which he trusts to others. It is especially important never to suppose that plants are the same whose names are the same. Upon this point it particularly behoves the botanist to be vigilant; for nothing is more common than for writers to mistake the plants intended by each other. Thus, R. pimpinellifolia of Linnæus, is R. spinosissima; R. pimpinellifolia of Pallas is a distinct variety, if not species, called altaica by Willdenow; R. pimpinellifolia of Villars is Rosa alpina ; R. pimpinellifolia of Bieberstein is probably R. grandiflora. Care must also be taken not to suppose that the plants with different names are different species. It frequently happens that a known species, already described by one Botanist, is described as new by another.
This arises from a variety of causes: the original description is imperfect or inaccurate, so that the species to which it refers cannot be recognised; or a species may have been described by one Botanist, in a work unknown to another, who has therefore described it anew. This is an evil for which there is no other remedy than vigilance on the part of those who take the lead in science; and who, from time to time, apply themselves to purify it from the errors that are daily accumulating. So difficult, however, is it to detect repetitions, that, even in the publications of the most distinguished and skilful writers, they occur in numberless instances: for instance, the Unonas uncinata, hamata, and esculenta of Dunal and De Candolle are identically the same.
To a Botanist who studies the science with much attention, and with a view to becoming perfectly acquainted with it, neither books nor the most elaborate descriptions prove sufficient. He finds it indispensable to have continually within his reach some portion of as many species as he can procure. If he has admission to a botanical garden, a great many species may thus be readibly accessible; although, even in such a case, it is only at particular periods that he can study the flowers and fruits of any of them: a garden, too, seldom contains more than a fifteenth or a tenth of the number of known species; and far more frequently not a twentieth.
For these reasons, Botanists have contrived a method of preserving, by drying and pressure, specimens of plants which represent all that it is most essential to recognise. A collection of such specimens was formerly known by the expressive name of Hortus siccus ; but is now universally called a Herbarium. If well prepared and arranged, such a collection is invaluable to any working Botanist, because it enables him instantly, at all times, to compare plants themselves with each other, and with the accounts of other Botanists; or to examine them with reference to points of structure not previously considered. It will, therefore, be useful to explain, shortly, the best modes of preparing, arranging, and preserving herbaria.
What is called the specimen of a plant is a small shoot bearing flowers and fruit, either together or separately, pressed flat and dried, so that it may be conveniently fixed upon a sheet of paper. As a plant is, in all cases, an aggregation of individuals growing upon exactly the same plan, and producing the same kind of reproductive organs, it follows that a single shoot, comprehending leaves, flowers, and fruit, is a representation of the largest tree of the forest, and will give as distinct an idea of the individual as if a huge limb were before the Botanist. It is this fact that enables us to form herbaria. Besides the dried twigs thus described, a herbarium should contain specimens of the wood of each species, and also a collection of fruits and seeds, which, being often large, hard, and incapable of compression, are not fit to be incorporated with the dried specimens themselves.
In selecting specimens for drying, care must be taken that they exhibit the usual character of the species; no imperfect or monstrous shoot should be made use of. If the leaves of different parts of the species vary, as is often the case in herbaceous plants, examples of both should be preserved.
The twig should not be more woody than is unavoidable, because of its not lying compactly in the herbarium. If the flowers grow from a very large woody part of the trunk, as is often the case in some Malpighias, Cynometra, &c., then they should be preserved with a piece of the bark only adhering to them. It is also very important that ripe fruit should accompany the specimen. When the fruit is small, or thin, or capable of compression without injury, a second dried specimen may be added to that exhibiting the flowers; but when it is large and woody, it must be preserved separately, in a manner I shall presently describe.
Next to a judicious selection of specimens, it is important to dry them in the best manner. For this purpose various methods have been proposed ; some of the simplest and most practicable may be mentioned. If you are in a country where there is a great deal of sun-heat, it is an excellent plan to place your specimen between the leaves of a sheet of paper, and simply to pour as much sand or dried earth over it as will press every part flat, and then to leave it in the full sunshine. A few hours are often sufficient to dry a specimen thoroughly in this manner. But in travelling, when conveniences of this kind cannot be had, and in wild uninhabited regions, it is better to have two or more pasteboards of the size of the paper in which your specimens are dried, and some stout cord or leathern straps. Having gathered specimens until you are apprehensive of their shrivelling, fill each sheet of paper with as many as it will contain ; and, having thus