SPRING FLOWERS 141 



bracts, which can be easily made out, but the whole inflorescence 

 is so condensed and shortened that it is difficult to follow the 

 branching in detail. 



The flower (Fig. 72) is an interesting one, and deserves careful 

 and repeated study. All the flowers stand in a definite position 

 with regard to the shoot, so that a front and back and two sides 

 can be distinguished. Unlike such flowers as the Buttercup and 

 Primrose, which are symmetrical about the central point, that 

 of the Dead-nettle can only be divided into similar halves by one 

 plane. This passes through the flower from front to back. Such 

 a flower is described as irregular, in contrast to the regular flowers 

 mentioned above, and it will be found that this feature leads to 



FIG. 72. White Dead-nettle. A, flower from the side ; B, flower cut 

 in half ; C, lower part of a flower cut in half more highly magnified. 

 (After Baillon.) 



a greater precision in the relation between the parts of the flower 

 and visiting insects than is usual in regular flowers. 



The five sepals are united to form a tubular calyx, from the 

 margin of which the pointed tips of the sepals project. One sepal 

 stands in the middle line of the flower behind. The calyx is green 

 with purplish markings, and the tubular part is ridged. The 

 petals are also joined together to form the corolla, which is tubular 

 below but divided into two well-marked lips at the upper part. 

 The lower lip, which widens out and has an indentation in front, 

 is composed of one petal. The sides of the entrance to the tube 

 are bounded by pointed lobes, which mark the position of lateral 

 petals ; while the upper lip, though undivided, is made up of two 

 petals. This can be shown by comparison with related plants, 



