A LE88OK OX BUTTERCUPS. 209 



It is a remarkable fact that the numbers of plants are 

 so great and their distribution often so crowded that there 

 is competition for these universally disseminated elements 

 (" struggle for existence ",. It seems strange that air and 

 sunshine, for example, in which the world is bathed should 

 be denied or restricted in amount to any living thing. Yet 

 nothing is easier to understand than how plants may put 

 each other in the shade and in this way impair their power 

 of using the air in food-making. In the struggle for the 

 best places multiplicity of " adaptations " will be found to 

 exist, and some of these we seek to understand. 



DETAILS OF STRUCTURE. 



Let us now examine the buttercup in more detail. 



The root consists of spreading fibrils, being of what is 

 known as the adventitious type. There are delicate hairs 

 on the parts nearest to the growing points, and to these the 

 soil adheres. These should be looked for with a good lens. 

 The stronger fibrils moor the plant in the soil, the root 

 hairs do the work of absorption. 



The stem is long and slender and of firm consistence. It 

 is nearly smooth, hollow, but solid at the nodes, reddish at 

 the base. There are several nodes at the base undeveloped, 

 but the others up the stem are fully so. Branches similar 

 in appearance to the stem arise in the axils of the leaves at 

 the nodes. The stem terminates in a single flower, as do 

 also the branches. 



At the base of the stem leaves consist of sheath, leaf- 

 stalk (petiole), and blade. The sheath is more or less mem- 

 branous, but, except at the edges, fairly firm. The leaf 

 stalk has a furrow on the upper surface and is hairy. The 

 blade is three or five-lobed, the lobes are deeply segmented, 

 and the plan of venation is palmate. The surface is hairy. 

 Further up the stem the leaf stalk becomes progressively 

 shorter, ultimately disappearing, whiLt the lobes become 

 almost lanceolate with short lateral segments. The arrange- 

 ment of the leaves upon the stem is alternate (Fig. 79). 



N.S. U 



