BOOK XVI.
CLASSIFICATORY SCIENCES.
BOTANY.
FOR the purpose of giving to my reader some indication of the present tendency of Botanical Science, I conceive that I cannot do better than direct his attention to the reflections, procedure, and reasonings which have been suggested by the most recent extensions of man’s knowledge of the vegetable world. And as a specimen of these, I may take the labors of Dr. Joseph Hooker, on the Flora of the Antarctic Regions,[41] and especially of New Zealand. Dr. Hooker was the Botanist to an expedition commanded by Sir James Ross, sent out mainly for the purpose of investigating the phenomena of Terrestrial Magnetism near the South Pole; but directed also to the improvement of Natural History. The extension of botanical descriptions and classifications to a large mass of new objects necessarily suggests wider views of the value of classes (genera, species, &c.,) and the conclusions to be drawn from their constancy or inconstancy. A few of Dr. Hooker’s remarks may show the nature of the views taken under such circumstances.
[41] The Botany of the Antarctic Voyage of H. M. Discovery Ships Erebus and Terror, in the years 1839–40. Published 1847. Flora Novæ Zelandiæ. 1853.
I may notice, in the first place, (since this work is intended for general rather than for scientific readers,) Dr. Hooker’s testimony to the value of a technical descriptive language for a classificatory science—a Terminology, as it is called. He says, “It is impossible to write Botanical descriptions which a person ignorant of Botany can understand, although it is supposed by many unacquainted with science that this can and should be done.” And hence, he says, the state of botanical science demands Latin descriptions of the plants; and this is a lesson which he especially urges upon the Colonists who study the indigenous plants. [632]
Dr. Hooker’s remarks on the limits of species, their dispersion and variation, are striking and instructive. He is of opinion that species vary more, and are more widely diffused, than is usually supposed. Hence he conceives that the number of species has been needlessly and erroneously multiplied, by distinguishing the specimens which occur in different places, and vary in unessential features. He says that though, according to the lowest estimate of compilers, 100,000 is the commonly received number of known plants, he thinks that half that number is much nearer the truth. “This,” he says, “may be well conceived, when it is notorious that nineteen species have been made of the Common Potatoe, and many more of Solanum nigrum alone. Pteris aquilina has given rise to numerous book species; Vernonia cinerea of India to fifteen at least. . . . . . . Many more plants are common to most countries than is supposed; I have found 60 New Zealand flowering plants and 9 Ferns to be European ones, besides inhabiting numerous intermediate countries. . . . . . So long ago as 1814, Mr. Brown drew attention to the importance of such considerations, and gave a list of 150 European plants common to Australia.”