146 



THE GREEN-HOUSE. 



j&ting by wind. Where the stem of a plant is fixed 

 by the common mode of tying, the wind may invigo- 

 rate the branches to such a degree as to render them 

 too heavy for the slender stem from which they issue, 

 and which, owing to the mode of tying, the wind 

 cannot invigorate. 



The habits of plants may be altered to a surprising 

 extent. The most vigorous timber tree, trained in 

 the horizontal manner against a wall, like a garden 

 pear-tree, will not produce its massy trunk, as when 

 exposed on all sides to the influence of the weather. 

 A shoot of the common pink, carnation, or sweet- 

 william, if left singly on a root and trained upright 

 to a prop, will form a not inelegant little evergreen 

 tree, and the same may be said of mignionette, and 

 some of the annual violets. Some annual plants, if 

 their flowers be constantly pinched off when they be- 

 gin to appear, will become perennial, and perennial 

 plants, forced, often become annual or biennial. 



Plants which have a natural tendency to propagate 

 themselves by suckers, bulbs, runners, &c., are ge- 

 nerally sparing in their production of seeds. Annual 

 plants can seldom be readily propagated by other 

 means than by seeds, and hence they are almost 

 always fertile in their production. In all woody 

 plants which propagate themselves abundantly by 

 extension, it will increase the tendency to produce 

 blossoms, to remove all suckers, and all shoots and 

 branches near the ground, by which the whole of the 

 vigour of the plant is thrown into its upper parts ; 



