. Cybele Britannica : or British Plants and their geographical relations. INTRODUCTORY EXPLANATIONS. 41 zones to be accurately traced within it; but the external shadings will show the three agrarian zones on the coast- It is probable that six such zones are quite as many as can be satisfactorily distinguished when attention must be directed to the whole surface of Britain. Even with six only, it would be useless to attempt very great precision in assigning the species to their respective zones. We must disregard the occasional and slight tresspass of a species into a zone above or bene
. Cybele Britannica : or British Plants and their geographical relations. INTRODUCTORY EXPLANATIONS. 41 zones to be accurately traced within it; but the external shadings will show the three agrarian zones on the coast- It is probable that six such zones are quite as many as can be satisfactorily distinguished when attention must be directed to the whole surface of Britain. Even with six only, it would be useless to attempt very great precision in assigning the species to their respective zones. We must disregard the occasional and slight tresspass of a species into a zone above or beneath those to which it is otherwise restricted by its natural adaptation to their cli- mate. Such trespasses (if the expression be allowable) are usually found in connexion with some local peculiarity by which the true climate is varied, or its influence on the plants modified. For example, the cool spray of a water- fall, or the efflux of a cold spring, will support the species of a colder climate than is natural to the latitude and ele- vation. And, on the contrary, the plants of a warmer cli- mate will grow on the south face of rocks which are raised above the altitude where the same species cease to exist in more bleak situations. These apparent exceptions come inconveniently in the way of precise lines on botanico-geo- G. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Watson, Hewett Cottrell. London
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Keywords: ., bookcentury1800, bookdecade1840, bookpublisherlondon, bookyear184
