6^ ROOT. [CHAP. 



may be referred to; but it must always be borne in mind that 

 the organs of plants — root, stem, leaf, and flower — are very 

 prone to accidental variation, especially in minor particulars, 

 so that occasionally I may be found apparently contra- 

 dicting Nature : but in such cases do not rest satisfied with 

 reference to a single specimen ; compare together a number 

 of specimens whenever it can be done, and you will then 

 find, I believe, the illustration confirmed. In explainiiig 

 the terms used to denote the mere outline and form of 

 organs, I have not generally referred to any illustration. 

 I leave them to the learner to find out for himself. 



2. The Root. — In the germinating Pea we find that the 

 root is developed by the direct downward elongation of the 

 radicle of the embryo. A root thus originating forms what 

 is termed a tap-root. We have good examples of this 

 primary root-axis in a large number of Dicotyledons, both 

 trees and herbaceous plants, though in many, by arrest, or 

 by repeated branching, it loses, more or less, its character 

 as a proper tap-root. In Monocotyledons, owing to the 

 origin of the root from root-buds which burst through the 

 undeveloped radicle of the embryo, we never have a tap- 

 root. In these plants the root generally consists of 

 numerous independent fibres, branched or unbranched. 

 It may be described simply as fibrous. Pull up any grass 

 and you will find such a root. 



Many plants which at first sight appear to be stemless 

 {acaidescc?it) we shall find possess a more or less creeping 

 stem, giving off root-fibres at the nodes. This is a very 

 frequent condition, and many herbaceous plants, both 

 Dicotyledons and Monocotyledons, are principally multiplied, 

 ind the area which they occupy extended, by such creep- 

 ing, root- producing stems. Roots originating in this way, 

 and not by direct prolongation of the radicle of the embryo, 



