In My Vicarage Garden 



such a doctrine, different from theirs, but per- 

 fectly true ; and that it is true is, I think, a very 

 remarkable fact, because the present arrangement of 

 plants was carried out with no reference whatever 

 to the medical or economic uses of plants ; yet 

 these uses do so range themselves under different 

 families that a knowledge of the structure of the 

 plants in any family is a great help in arriving at 

 a knowledge of the uses. In some cases the 

 qualities of a plant are shown not by the stem, 

 leaves, or flower, but by the juices ; as in the 

 Euphorbias and Asclepiads, where the white, 

 clammy juices at once give a warning that the 

 plant is to be suspected. And there is one curious 

 case in which a very small difference in the form 

 of the leaf is enough to show its qualities. Senna 

 is produced from different species of Cassia, and 

 in the imported drugs leaves are sent which are 

 very like the true ones, but which are useless. 

 The difference, however, is easily detected by 

 sharp eyes. The Cassia has compound leaves 

 with very small leaflets, and in the leaf of the 

 true Senna the two sides of the leaflets are un- 

 equal, one side being very slightly shorter than 

 the other ; if the sides are quite equal the true 

 drug will not be produced. 



Now the question naturally arises — Is there 

 really any connection between the structure of a 

 plant or colour of a flower and its medical uses? 

 Is it possible that the aromatic scents of lavender 

 or thyme can only be produced by a square 

 128 



