Page:Flora Hongkongensis.djvu/21

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15*
PREFACE.

disappeared. And notwithstanding the prevailing idea of the close connection of the Floras of Japan and Hongkong, suggested perhaps by the presence in both of a few striking species or genera (Kadsura, Stauntonia, Actinidia, Camellia, Eriobotrya, Distylium, Liquidambar, Benthamia, Farfugium, Houttuynia, etc.), I cannot enumerate 80 species known to be common to the two countries.

With Australia our Flora exhibits a few curious points of connection, either as species or types (such as Pycnospora, Lagenophora, Stylidium, Mitrasacme, Thysanotus, Philydrum, Lipocarpha microcephala, Arthrostyles, Zoysia, etc.). They are indeed all herbaceous, and are probably found in the intermediate Philippine and South Pacific islands; some of them also are maritime plants, which have always a wide range in latitude as well as longitude; yet it must be observed that many of them belong to genera which have many other herbaceous or maritime species, not one of which spreads beyond Australia itself. A few of the above-mentioned maritime species, like Carex pumila, extend from Australia to Japan. Other maritime plants belonging to the northern or Japanese Floras, as Ixeris debilis and repens, appear to have their southern limits in Hongkong.

With America the Hongkong Flora has no direct connection, the singular band of vegetation which appears to cross from N. America to Japan, and die off through Mantchuria in central Asia, some species extending as far as the Himalaya, passes to the north of Hongkong, although we may even there be reminded of it by a few such types as Lespedeza, Solidago, Eupatorium, Olea marginata, Gelsemium, etc. Those species which the island has in common with tropical America are almost all generally spread over tropical Asia and Africa, and offer nothing exceptional in their distribution, except perhaps the West Indian Teucrium inflatum, which appears to be abundant in several of the South Pacific islands, but unknown in tropical Asia generally.

The total number of species enumerated in the present work is 1056, distributed into 591 Genera and 125 Orders. From this however must be deducted 25 genera and 32 species which there is reason to believe are escapes from cultivation, or may only occur where they have actually been planted. Nearly 100 more species may be classed as weeds of cultivation,—"plantes cultivées malgré la volonté de l'homme," of A. DC.,—occurring, perhaps exclusively, in paddy-fields and other cultivated spots. Of these about 6 appear to be of American origin, about 12 more may have been introduced with European seeds; the remainder however are so widely spread, as weeds also, over tropical Asia, that