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THE CHARACTERISTICS OF THE PLANT. 



To what height a thriving plant is capable of ascending no man knows ; 

 for the loftiest sweep of rock, the tallest tree or tower, will be surmounted by 

 it in time if no accident occurs to stop its growth midway. Soon after 



emerging from its shell as a little plant with lobeless leaves, it begins to put 

 forth leaves that are distinctly lobed, and then the character of the plant is 

 in great part determined. In one district it will be found that the ivies are, 

 for the most part, uniformly three-lobed ; in another they are five-lobed ; in 

 another they will vary to such an extent that twenty or more distinct varieties 

 may be found in a single acre of woodland, or on one mass of rock or ruin. 

 Nor is it always needful to explore a considerable tract of ground to make 

 acquaintance with its distinctive variations, for all the forms it assumes in 

 one great tract of woodland may be sometimes represented by a single plant. 

 It conducts one some distance towards the romance of botany to find ivy leaves 

 of a dozen distinct forms, some of them remarkable for beauty or oddity, and 

 others of the most commonplace type, all growing on the same stem, and 

 suggesting to the observer that this plant is the Proteus of the vegetable 

 kingdom. Nevertheless, with all this variableness, it will be found that certain 

 typical characters prevail, and that every district possessing definite geological 



of ivy, 



or a 



^roup 



that 



and aerial characters has its own particular form 

 tends more or less to a local type. 



It is the nature of the plant to climb, and so far as we know to climb for ever. 

 But having reached the summit of its supporting fabric, its nature is changed. It 

 now ceases to produce holding-claws, and throws out tree-like branches instead of 

 slender clinging stems. The leaves on the branching stems are not lobed, and 

 they are invariably more or less ovate ; and, however various, tend invariably to an 

 ovate form, and are harder, smoother, and more glossy, than those on the climbing 

 stems. What occasions this change ? The cause undoubtedly is the loss of sup- 

 port. The plant cannot advance any higher, and its branches assume a horizontal 

 position, and the check thus occasioned in the flow of the sap is the secret of the 

 change in the aspects it presents. A careful examination of a plant which has 

 " crowned the edifice" will disclose several intermediate grades of form in the 

 leaves between those that are boldly lobed on the vertical surface, and those that 

 are without lobes above it. These intermediate leaves clothe stems that are in a 

 transitional state, and they strikingly illustrate the explanation offered above that 

 the check in the flow of the sap resulting from the change of attitude of the branch 

 is the cause of the change in the form of the leaves. Now, let us suppose that on 

 the top of a tower clothed with the tree-like growth of ivy we raise a pinnacle. 



