POLLEN. 



75 



and rolling -within their scaly envelopes, fertilize the ovaries. A curious fact is 

 stated by an Italian writer, viz., that in places about forty miles distant grew two 

 palm-trees, the one without stamens, the other without pistils ; neither of them 

 bore seed for many years ; but in process of time they grew so tall as to tower 

 above all the objects near them. The wind, thus meeting with no obstruction, 

 wafted the jwllen to the pistillate flowers, which, to the astonishment of all, began 

 to produce fruit. 



<?. The number of plants in which the pistils and stamens arc on different flowers 

 is few compared to those which have these important organs inclosed within the 

 same corolla ; as in our herbaceous plants, and the trees of hot countries, whose 

 leaves being always present might impede the passage of the pollen from other 

 trees. On the contrary, the trees of cold climates have generally the stamens and 

 pistils on separate flowers, blossoming before the leaves come forth, and in a windy 

 season of the year. Those which blossom later, as the oak, are either peculiarly 

 frequented by insects, or like the numerous kinds of firs, have leaves so little in 

 the way, and pollen so excessively abundant, that it can scarcely fail of gaining 

 access to the pistillate flower. In all cases the pollen and stigma are in perfection 

 at the same time ; in those flowers where the stamens and pistils are together, and 

 of an equal length, some are drooping and some erect ; but where the stamens are 

 longer than the pistil, the flower is usually erect ; where they are shorter, the 

 flower is pendent : nature thus provides for the fertilization of the germ by the fall 

 of the farina upon the stigma. 



Fig. 89, at A, repre- 

 sents a monoecious flow- 

 er of the genus Eu- 

 phorbia.* In the cen- 

 ler of the perianth, a, 

 is the infertile flower, 

 consisting of several 

 double stamens, c c, up- 

 on jointed filaments, dd; 

 b 13 the fertile flower, 

 with a petal-like stig- 

 ma. At B, the same 

 flower before blossom- 

 ing is represented as 

 cut vertically, to show 

 its internal structure at 

 this period. C shows 

 the same flower after 

 its fertihzation. Be- 

 fore the maturity of 

 the blossom the pistil was above the stamens, as seen at B. At the expan.sion of 

 the perianth It was below the stamens, as at A 6 ;-resuming its erect position, we 

 see the pistil at C, its ovary having become a fruit filled with swelling seeds. 



In the laurel (Kalmia) the ten sta- 

 mens are confined by their anthers in 

 ten cavities of the live-parted, mono- 

 petalous -corolla. When the flower is 

 mature, the anthers suddenly spring 

 from their confinement, and scatter 

 their pollen upon the stigma. Fig. 90, at A, represents tlie 



• Euphorbia illyrica.—M\xhe\. 



Fig. 89, 



^amrcorX^'^rL^" ^''^'m "^"'^'""-7^^^ countries have mostly sUniens and pistils on the 



Hiiicli tne objects ol nature are accomplisRed— Explain Fig. SO-Explain Ki-. HO. 



