FORM AND POSITION OF THE TRANSPIRING LEAVES AND BRANCHES. 



337 



peculiarity. lu the Spanish flora, for example, is an UmbelHfer {Bupleutmm 

 verticale) whose leaves are so twisted with regard to the sun that they remind one 

 forcibly of the Australian acacias. Many Composites, especially tlie widely-distri- 

 buted Wild Lettuce (Lactuca Scanola), growing on dry soil in Central Europe, 



Fig. 84.— Compass Plants. 



^SUphium lacinMum, seen from the east. - The same plaut seen from the south, ^ Lactuca Scariola, seen from the east. 

 4 The same plant from the south. Both species are considerably reduced. 



exhibit this contrivance in a striking manner. A Composite shrub, Silphiuni 

 laciniatam, to be found in the prairies of Noi-th America, from Michigan and 

 Wisconsin as far south as Alabama and Texas, has obtained a certain renown by 

 reason of the remarkable twisting of its leaf -blades. It long astonished hunters 

 in the prairies that in these plants (represented in fig. 84) the leaf -laminae, especially 

 those springing from the lowest portions of the stem, not only assumed a vertical 



Vol. I. 22 



