228 BEAUTIFUL FLOWEKS 



parallel case, among popular modern flowers, to the tardy develop- 

 ment of the Sweet Pea. 



There is a distinct physiological reason for this. Plants have 

 different sexual systems. The majority have both sexes united in 

 one flower, and the organs of fertilisation are mature when the 

 flower is expanded, thus affording scope for cross-fertilisation by 

 insect agency, bees and other insects passing from flower to flower, 

 and conveying pollen on their bodies from the anthers of one to 

 the stigma of another. The Sweet Pea belongs to this majority, 

 but the organs are mature while it is yet in the bud stage, and 

 before it expands, with the result that self-fertilisation is inevitable. 



It is because the Sweet Pea had this peculiarity (and the fact 

 is certainly uncommon) that varieties multiplied very slowly. Had 

 the flower been of the ordinary class it is quite certain that new 

 varieties would have come more quickly, because cross-fertilisation 

 through external agency would have come into play, with its usual 

 far-reaching effects. 



Much has been written respecting the possibilities of the Sweet 

 Pea being cross-fertilised by means of insects. It is fully recognised 

 that if cross-fertilisation is to take place at all it must be through 

 the action of some insect which has learned how to penetrate the 

 defences of the flower, or by wind conveying pollen to exposed 

 organs. Observers have recorded the visits of bees to undeveloped 

 blossoms, and of their getting access through the "keel" (the sac 

 formed by the infolding of the lower petal). But there is no 

 certainty that the flower had not " selfed " (i.e. become self- 

 fertilised) beforehand : probably it had. Again, growers of Sweet 

 Peas are quite familiar with a small black beetle, about ^ inch 

 long, which crawls about the flowers, and probably gets into 

 the buds. It is possible that this little insect could convey 

 pollen from one flower to another ; but even if it did, there 

 is the probability that self-fertilisation had taken place before the 

 transference of pollen had an opportunity of exerting any influence. 



