SPRING FLOWERS 95 



has been made by a number of valuable studies, notably 

 Dr. Marion Newbigin's Colour in Nature, our knowledge 

 of the composition, origin, and primary import of pigments 

 is still scanty. With this caution in mind, we adhere to 

 the thesis that the heightening of colour is associated with 

 the increased intensity of sunshine, though this does not 

 necessarily mean that the correlation is one of direct cause 

 and effect. It is plain, for instance, that most of the 

 flowers are adapted for insect-pollination, not wind-pollina- 

 tion, and it may be argued that the flower-visiting insects 

 which increase in number as the Summer sets in have 

 throughout long ages consistently selected the variants in 

 the direction of brighter coloration. But we must return 

 to this subject. 



In a very interesting essay on " The Philosophy of 

 Flower Seasons " (American Naturalist, 1893, pp. 769-781), 

 Mr. Henry L. Clarke has maintained the thesis that the 

 more primitive flowers tend on the whole to appear earlier. 

 Let us illustrate his line of argument. 



Though there are among Monocotyledons some very 

 highly specialised forms, such as orchids in one direction 

 and grasses in another, it is generally admitted that Mono- 

 cotyledons represent a lower grade of evolution and an 

 older stock than most of the Dicotyledons. 



Now, what place do the Monocotyledons take in the 

 year's procession ? Think of snowdrops, daffodils, irises, 

 wood hyacinths, and so on. The general statement is 

 surely that, apart from specialised forms, the great majority 

 of Monocotyledons flower in Spring or early Summer. 

 The specialised grasses, on the other hand, culminate in 

 Summer, and some continue on into Autumn. The less 

 specialised sedges are distinctly earlier, thus the genus 

 Carex culminates in May, though the type-genus Cyperus 

 belongs to August and September. Similarly, Liliaceae 



