REPRODUCTIVE ORGANS OP PLAJfTS. 293 



The forms of anthers, as well as of the grains of pollen, vary with nearly 

 every kind of plant. The yellow pollen of pine and spruce trees is not 

 infrequently transported by the wind to a great distance, and when 

 brought down by rain in considerable quantities, has been mistaken for 

 sulphur. 



The Pistil,^, in fig's 60 and 61, or pistils, occupy the 

 center of the perfect flower. They are exceedingly va- 

 rious in form, but always have at their base the seed-ves- 

 sels or ovaries, ov, in which are found the ovules (little 

 eggs) or rudimentary seeds. The summit of the pistil is 

 destitute of the epidermis which covers all other parts of 

 the plant, and is termed the stigma, st. 



As has been remarked, the floral organs may be consid- 

 ered to be modified leaves ; or rather, all the appendages 

 of the stem the leaves and the parts of the flower to- 

 gether are different developments of one fundamental 

 organ. 



The justness of this idea is sustained by the transforma- 

 tions which are often observed. 



The rose in its natural state has a corolla consisting of 

 five petals, but has a multitude of stamens and pistils. In 

 a rich soil, or as the effect of those agencies which are 

 united in " cultivation," nearly all the pistils and stamens 

 lose their reproductive function and proper structure, and 

 revert to petals ; hence the flower becomes double. The 

 tulip, poppy, and numerous garden-flowers, illustrate this 

 interesting metamorphosis, and in these flowers we may 

 often see at once the change in various stages intermediate 

 between the perfect petal and the unaltered pistil. 



On the other hand, the reversion of all the floral organs 

 into ordinary green leaves has been observed not infre- 

 quently, in case of the rose, white clover, and other 

 plants. 



While the complete flower consists of the four sets of 

 organs above described, only the stamens and pistils are 

 essential to the production of seed. The latter, accord- 



