42 



Torus or 

 sceptacle. 



Pollination 

 Fertilisation. 



eventually developing into what are known as seeds), an 

 elongated neck called the style, which is frequently more or 

 less expanded at its apex and there forms the so-called 

 stigma. The stigma is a specially differentiated part of the 

 style, usually with a moist and sticky surface, which varies 

 greatly in shape and size ; sometimes it is a rounded knob ; 

 sometimes it is merely a single, or double, line running along 

 the side of the style, while sometimes the apex of the style is 

 forked and the sticky surface of the stigma (called the stig- 

 matic surface) is found on the branched tip of the style. The 

 essential parts of the pistil are the ovary and the stigma. 

 The style may be, and often is, absent, the stigma then 

 being sessile. The ovary being the principal part of a pistil, the 

 word ovary is often used to signify the whole pistil. A flower 

 may contain one or several pistils. 



The perianth leaves, stamens and pistils are all inserted 

 c j ose together on the more or less expanded apex of the 

 flower -stalk and this portion of the stalk from which the 

 floral organs spring is called the torus, or floral receptacle. 



3 8> The object of the flower is 



^ P r duce seeds which are capable of developing new and 

 independent plants. No seeds, however, can arise in a pistil 

 unless some of the powdery pollen which is contained in the 

 anthers is able to reach the stigma. The small grains of pollen 

 which happen to be caught by, and to adhere to, the sticky 

 stigma develop minute tubes which penetrate the style and 

 grow down into the ovary to the ovules, the contents of each 

 pollen grain passing into its tube. When one of these tubes 

 reaches an ovule, a part of its contents pass into and fuse 

 with a part of the contents of the ovule, which is then said 

 to have been fertilised and which thereafter grows and 

 develops into a seed, containing the embryo of a new plant. 

 The transference of pollen to the stigmas (pollination) is 

 thus of vital importance, it being essential for fertilisation 

 and the production of seeds. In some plants such as 

 Grasses, this is done by the wind and these plants have no 

 conspicuously-coloured flowers ; in other plants this work is 

 done by insects and birds who visit the flowers for the sweet 

 juice, or nectar, which they contain, get dusted by pollen in the 

 process, and carry this away to the stigmas of other flowers. 

 Those flowers which can be most easily seen and found by birds 

 and insects obviously therefore have the best chance of being 

 visited and of having their ovules fertilised, and this is the 

 reason why so many flowers possess conspicuous and brightly 



