THE JiEASON WHY. 309 



He shall oe like a tree planted by the rivers of water, that bringeth forth his 



fruit in season: his leaf also shall riot wither; and whatsoever he doeth 



shall prosper," PSALM i. 



the Zamang del Guayra, a species of mimosa, the pendant branches of tho 

 hemispherical head having a circumference of upwards of 6i0 feet. '] \M 

 Adansonia, or baobab of Senegal, though attaining no great height, rarely more 

 than fifty feet, has a trunk with a diameter sometimes amounting to 3i feet ; 

 waile the Pinus Lambertiana, growing singly on the plains west of the Rorky 

 Mountains, has been found 250 feet high, 60 feet in circumference at the I..IM-, 

 4' feot in girth at the height of 190 feet, yielding cones 11 inches round, and l*i 

 long. The Ficus Indicus, or banian tree, sending out shoots from its horizontal 

 branches, which reaching the ground take root, and form new stems till a 

 single tree multiplies almost to a forest, has been observed covering an an a of 

 1700 square yards. 



1214. From the number of concentric zones observed in a transverse section 

 of the stems De Caudolle advances proof of the following ages : 



Elm . . . . ... ... 335 years. 



Cypress about 350 



Cheirostemon ,,400 



Ivy .... ., ... ... . 450 



Larch . . . \ ,' .'.' i . . 576 

 Orange . . . . .. 630 



Olive . , -..' . ... 700 



Oriental Plane ,, 720 and upwards. 



Cedar of Lebanon ,,800 



Oak . . . . . 810, 1080, 1500 

 Lime . . . ." . . . 1076; 1147 

 Yew . . . . . 1214, 1458, 2588, 2880 

 Taxodium . . ... 4000 to 6000 

 Boabab 5150 



1215. Admitting, with Professor Henslow, that De Candolle overrated the aires 

 of these trees one-third, they are examples of extraordinary longevity. Yew 

 trees upwards of 700 years old remain at Fountains Abbey, Yorkshire, as thera 

 is historic evidence of their existence in the year 1133. But a yew in the church- 

 yard of Darley-in-the-Dale, Derbyshire, is considered by Mr. Bowman as 2 ;oo 

 years old. 



1216. The cryptogamous plants afford the most numerous examples of wide 

 diffusion. A lichen indigenous in Cornwall, sticta aurata, is also a native of tho 

 West India Islands, Brazil, St Helena, and the Cape of Good Hope ; while 3 > 

 lichens and 28 mosses are common to Great Britain and Australia, though th;> 

 general vegetation of the two districts is remarkably discordant. Some species 

 of endogenous plants are also widely distributed, the Phleum alpinum of 

 Switzerland occurring without the slightest difference at the Strait of Magellan, 

 and the quaking grasses of Europe in the interior of Southern Africa. But only 

 in very few instances are the same species of exogenous plants met with in 

 regions far apart from each other ; and generally speaking, in passing from one 

 country to another, we encounter a new flora ; for if the same genera occur, the 

 species are not identical, while in distr cts widely separated the genera are 

 different. 



1217. The cryptogamic plants, mosses, lichens, ferns, and fungi, are to the 

 whole mass of phaenogainic vegetation in the following proportions in different 

 districts: Equatorial latitudes, deg. to 10 deg.; on the plains, l-25th, on tb> 

 mountains, l-5tb ; mean latitudes, 45 deg. to 52 deg. \ ; high latitudes, 67 <tec. 



