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vein with side veins. 3id. Some trees, such as the beech, the birch, 

 the elm, send up one large main stem, from which, throughout its 

 length, there proceed comparatively small branches pretty equally 

 along the axis, and it will be found in such cases that the leaf has a 

 central vein, with pretty equally disposed veins on either side. 

 Other trees, again, tend rather to send off, at particular heights, a 

 number of comparatively thick branches at once. This is the 

 case, for instance, with the common sycamore, the chestnut, and 

 the laburnum. The trunk of the sycamore [Acer Pseudo-plaianus) , 

 about eight or ten feet above the surface of the ground, com- 

 monly divides itself into four or five large branches, and in precise 

 analogy we find the leaf at the top of a pretty long leaf-stalk sending 

 off four or five large veins. The chestnut tends to send off at the 

 top of the unbranched trunk a still greater number of branches, and 

 we find in correspondence with this that its leaf is commonly divided 

 into seven leaflets. The laburnum (and also the broom and clover) 

 goes off in triplets in respect of leaflet and ramification. In such 

 cases it will commonly be found that the leaf is compound, and we 

 are to regard all such compound leaves as one, and representative of 

 the whole tree. Generally it is the whole leafage coming off at a 

 given place, which represents the whole tree ; and the single leaf, 

 when there is a number of leaves, represents merely the branch. 4th. 

 Some plants, such as the Rhododendron, the Azalea, and the lupin, 

 send off leaves which have a tendency to become whorled, and their 

 branches have also a tendency to become verticillate. 5th. The 

 stems of some trees, such as the thorn and laburnum, are not straight, 

 and the branches have a twisted form ; and it will be found that the 

 vein of the leaf of these trees is not straight, and that the leafage is 

 not in one plane. This is also seen in the elm. 6th. In some trees, 

 such as the beech, the stems go off in nearly straight lines, and the 

 leaves are found to have a straight venation. In other trees, again, 

 such as the chestnut, the branches have a graceful curve, and the 

 veins of the leaves are curved in much the same way. 7th. In most 

 plants the angle at which the side stems go off will be found to 

 widen as we ascend to the middle, and thence to decrease as we 

 ascend to the apex, and the venation of the leaves will be found to 

 obey a similar law. This helps to give both to tree and leaf their 

 beautiful oval outline. In some plants, again, such as the poplar and 

 birch, the angles are widest at the base, and tend to narrow as we 

 ascend, and both leaf and tree in such cases assume a kind of trian- 

 gular form. 8th. Generally we shall find a correspondence between 

 Vol. IV. 2 o 



