28 NATURAL HISTORY OF PLANTS. 



as may be inferred from what is just said, that have never been 

 found but on one particular spot. For instance, Thunberg found 

 on the Table mountain, at the Cape of Good Hope, and in one place 

 only, the Disa longicorms, and Serapias tabular is, and never 

 afterwards observed them elsewhere. Tonrnefort gathered from a 

 single rock of the small island Amorgos, in the Arcbiepelago of the 

 Mediterranean, the Origanum Tournefortii. Sibthorp, who made 

 the same journey long after him, found that plant no where except 

 on that very spot. 



Countries that are now separated by the ocean, might formerly 

 have been joined, at least the plants they have in common autho- 

 rize the supposition. In this way might the most northern part of 

 America have been connected with Europe, and New Holland with 

 the Cape of Good Hope \. thus too lie island of Norfolk might have 

 been joined to New Zealand, &c. For North America produces 

 several of the smaller European plan^, and in New Holland grow 

 some of the plants peculiar to the Cape of Good Hope. In like 

 manner New Zealand, which has a Flora quite different from that 

 of the neighbouring continent of New Holland, possesses most of 

 the plants that are found on Norfolk island, particularly the New 

 Zealand flax, Phormium tenax. Of this more examples might be 

 produced if we had room for them. 



Besides the manner in which we have said it is probable that 

 plants have been dispersed over the globe, there are other circum- 

 stances that have contributed to spread some plants to a distance 

 they would not otherwise have reached. Many seeds are furnished 

 with hooked prickles, which take hold of the hair of animals, and are 

 thus transported to a distance. Birds go in search of various seeds, 

 and drop them often many miles off. The seeds of many aquatic 

 plants cling to the feathers of birds that frequent the waters, and 

 quit them when they alight in places far remote. 



The seeds of most plants, when perfectly ripe, sink to the bottom 

 in water. If they are contained in a hard shell, they remain a 

 long time fresh. Some feet under.grouud, and at the bottom 

 of the sea, some plants will remain a long time in a state fit for ve- 

 getation. At these depths no air can reach them and protected 

 from the access of this, they are not destroyed. 



It appears too that rivers and seas may transport plants to far 

 distant plaees. Ripe and fresh seeds from the West Indies are 



