GLASGOW SOCIETY OF FIELD NATURALISTS. Ill 



and to this the term dioecious is applied. She may caixse the organs 

 of reproduction to reach their maturity at different times, and to 

 this the term dichogamy is applied. The term protandrous dicho- 

 gamy is applied to those cases in which the stamen is the first to 

 mature, and the term protogynous dichogamy to those cases in 

 which the female is the first to reach maturity. 



Again, we may have the male and female organs of different 

 lengths. The term dimorphous is applied to those cases where 

 we have two different lengths, as in the primrose. In the one 

 form of the primrose (Fig. 2) the pistil is short and situated about 

 the middle of the corolla tube, while the stamens are long and lie in 

 the throat of the corolla. In the other form (Fig. 1 ) the positions 

 are reversed, the stamens are short and situated in the middle of 

 the corolla tube, while the pistil is long and occupies the throat of 

 the corolla. The term trimorphous is applied to those cases where 

 we have three different lengths, as in Lythrum and Oxalis. 



Again, we may have the stamens developed in such a manner 

 that it is quite impossible that they can fertilise the plant unless 

 removed by insects. We have good examples of this in the various 

 species of Orchidaceous plants. 



Or lastly, nature may develope pollen that has no effect on the 

 pistil of the same plant, or even on the flowers of the same plant 

 on which it is situated. 



Until very lately it was supposed that male and female organs 

 were developed on the same plant in order that the plant might 

 the more easily be fertilised ; but I am sure that if the fertilisation 

 of the various flowers be carefully examined, it will be found that 

 self-fertilisation is the exception, and not the rule as was formerly 

 supposed. 



Among the various flowers we will find contrivances for the fertili- 

 sation of one flower by the pollen of another as perfect and varied 

 as the most beautiful adaptation found in the animal kingdom. 



For the sake of convenience, I have divided flowers into two 

 great classes, according as they are fertilised by the wind, or by 

 means of insects. 



Plants that are fertilised by the wind have, as a rule, no proper 

 floral envelopes, no development of nectar, and very loose pollen 

 granules. Plants fertilised by means of insects have conspicuous 

 floral envelopes, a development of nectar, and more or less coherent 

 pollen. 



