The group of islands and rocks known collectively as the “Chatham Islands” lies isolated in the South Pacific Ocean, at a distance of about four hundred and fifty miles east-south-east from the nearest point in New Zealand. It lies between the parallels 43° 30′ and 44° 30′ south latitude, and the meridians 175° 40′ and 177° 15′ west longitude. The largest member of the group—Chatham Island—is about thirty miles in length, and contains 222,490 acres. Pitt Island is next in size, with a length of barely eight miles and a half, and an area of about 15,000 acres. The only other islands sufficiently large to contain flowering-plants to any extent are Mangere and South-east Island, each of which is about a mile and a half in length. Pitt Island lies to the south of Chatham Island, from which it is separated by a narrow passage of water, about fourteen miles in width, called Pitt Strait. Mangere lies to the west and South-east Island to the south-east of Pitt Island, from which the former is distant a mile and a half and the latter a mile and a quarter.
The botanical history of the Chathams dates from the year 1840, when Dr. Dieffenbach visited the islands on behalf of the New Zealand Company, and made at the same time a small collection of the plants. These are recorded in the “Flora Novæ-Zelandiæ,” and comprise only some twelve species of phanerogams and vascular cryptogams. For a space of eighteen years after Dr. Dieffenbach's visit nothing more was done botanically, when, a direct trade being established between Melbourne and the islands, a few plants were from time to time brought to Baron F. von Mueller, including the remarkable Myosotidium nobile (45, p. 2); but it was not until the year 1863 that the first real botanical exploration of the
islands was undertaken, when Mr. W. T. L. Travers, who previously had done so much to advance the knowledge of New Zealand botany, sent his son, Mr. H. H. Travers, to Chatham and Pitt Islands to make as complete a collection of the indigenous plants as possible. The expedition resulted in a very interesting collection of plants, from which Baron F. von Mueller compiled his well-known work “The Vegetation of the Chatham Islands.” This was published in 1864, and contains descriptions or notes of 129 species of phanerogams and twenty-five species of ferns and lycopods, of which seven were species new to science. Had the distinguished author of the work not been a most staunch believer in the fixity of species (45, pp. 7 and 8), the number of species recorded would have been considerably larger, in proof of which statement it is only necessary to note his treatment of Veronica, Calystegia, Epilobium, and certain other genera.
In 1867 a paper appeared (24), written by Mr. Halse, which gives a most excellent idea of the general aspect of certain parts of the main island. Much more important, however, is the account of his journey in 1863 by Mr. H. H. Travers, published in the first volume of the “Transactions of the New Zealand Institute” in 1869 (51). In 1871 Mr. Travers paid a second visit to the islands, and his new collection added very considerably to the known number of their plants. Baron F. von Mueller contributed a short note on this collection to the “Transactions of the New Zealand Institute” (46), giving a list of certain genera* not collected during Mr. Travers's former visit.
In 1874 Mr. John Buchanan published a revised list of the flowering-plants and ferns of the Chatham Islands, based on the two collections of Travers (3), bringing the genera up to 129 and the species to 205, describing three new species and recording the occurrence of that very interesting restiaceous plant Sporadanthus traversii, now referred to the genus Lepyrodia (32, p. 969). Mr. Buchanan's list seemed at the time it was published to quite exhaust the possibilities of the Chathams as a field for new species, and so for many years Chatham Island botany appeared to be at a standstill. But during part of that time a most enthusiastic naturalist, Mr. F. A. D. Cox, who resides in Chatham Island, was collecting and studying its plants during his few intervals of leisure, so when the late Mr. T. Kirk sought aid with regard to Chatham Island plants, during the compilation of the “Students’ Flora of New Zealand,” Mr. Cox was very able and very willing to supply him with material, and, better still, with information
[Footnote] * In this list Myosotis is noted, so I was mistaken in writing of it as an unrecorded genus for the Chathams (11).
gathered at first hand from the plants themselves. In consequence of this valuable assistance Mr. Kirk treated the flora of the Chathams in a more searching and thorough manner than had been the case previously.
From the foregoing short history of the botany of the Chathams, it may readily be seen that botanists and collectors have been mainly concerned with the classification and finding of plants, and that very little indeed has been published regarding the plant-covering itself, the plant-formations, the conditions under which the members of the formations are living, the plant-forms which these conditions have evoked or preserved, the changes which civilised man has brought about in the vegetation, or many other matters of high œcological interest. It was with the intention of observing and studying such matters, and, above all, in the hope of being able to put on record a fairly accurate picture of a most remarkable vegetation, doomed in its primeval condition to extinction, that I paid a visit to Chatham Island at the beginning of this present year 1901. I stayed on the island during part of January and February, six weeks in all, but did not visit any of the other islands, so the details in this paper refer only to the vegetation of the principal member of the group, as notified in the title. I had not time to visit every part of the island. Details on this head are noted in the part of this paper dealing with the physiography; here it need only be mentioned that I camped for eleven days on the southern tableland, and was thus enabled to examine with some degree of care the vegetation of a portion of the island not previously visited by any botanist. And this was the more important since there alone may be seen tracts of country clothed with unaltered primeval vegetation, but which unique and interesting spots are every day becoming fewer in number and more limited in extent, so that without doubt in a year or two there will be no longer any virgin plant-formations on the island, except those of inaccessible rocks or of the larger pieces of water. As I write, Mr. W. Jacobs sends me word that the previously inaccessible forest lying under the precipitous cliffs of the south coast has been opened up to stock, and in consequence the last remnant of the Chatham Island forest will soon be a thing of the past so far as its primitive physiognomy is concerned.
Although Chatham Island is only small, its very irregular shape, the great lagoon which occupies its centre, and the difficult travelling through a vegetation sometimes extremely dense would require a much longer time than I was able to devote in order to make anything like an exhaustive examination of the plant-covering. This paper must be looked upon, then, as an introductory and most general one, and intended
merely to pave the way for much more thorough œcological investigations. I have purposely usually only treated with any detail those plants which are endemic, and in this case the sins of omission are many, while a too rapid examination of most of the formations has probably in some cases led to error.
Before concluding this introduction I must express my most hearty thanks to all those residing on Chatham Island with whom I came in contact. All sought to render me every assistance possible, and whatever success may have attended my visit is due principally to their great hospitality and extreme kindness. Also, I must specially express my great obligation to the following: Mr. F. A. D. Cox, Mr. A. Shand, Mr. E. R. Chudleigh, Mr. W. Jacobs, Captain F. W. Hutton, F.R.S., Mr. T. F. Cheeseman, F.L.S., Mr. D. Petrie, M.A., F.L.S., and Mr. H. Carse.