100 LABORATORY STUDIES OF THE FLOWER 



that the stigma is raised on a more or less slender column, the style. 

 When seated on the ovary the stigma is sessile. Draw the pistil and 

 label the parts. 



Draw the ovary with walls removed, side view, to show the ovules 

 in position (x 4-6); end view, to show placentation and number of 

 cells of ovary (x 3-5). 



Examine the ovules, removed, with the highest power of the dis- 

 secting microscope, or, perhaps, with a compound microscope. Draw a 

 side view, including the little stalk of attachment to the placenta. 



EXERCISE XXX. THE POLLEN 



Examine the organs standing next to the pistil the stamens. 

 Find one opened and shedding its yellow, mealy contents, the pollen ; 

 and one not yet opened. 



f .f a high power is available examine and draw the individual 

 grains. 



Cut a thin cross section o ? . the unopened stamen to show the 

 cavities in which the pollen is produced the pollen sacs. 



Note where the pollen sacs open, or dehisce. 



Draw a stamen (x 2-3). The stalk is the filament. The pollen- 

 bearing terminal portion is the anther. The continuation of the fila- 

 ment, or the part that connects the pollen sacs, is the connective. Label 

 all parts. Draw anther, side view, to show dehiscence ( x 3-5) ; cross 

 section of anther showing the pollen sacs ( x 5-10). 



The really essential parts of the flower have now been seen. The 

 ovules, acted upon by the pollen, give rise to new plants. Many 

 flowers have no other parts than pistils or stamens ; that is, no pro- 

 tecting envelopes such as the brightly colored leaves of the flower 

 which i> now being studied. These leaves are of great service in pro- 

 moting the transfer of pollen from flower to flower and in protecting 

 the pistil and stamens while they are maturing. But they take only 

 an indirect, not a strictly necessary, part, in reproduction. 



EXERCISE XXXI. THE FLORAL ENVELOPES 



Are there two sets of the floral leaves ? Do they differ in any 

 respect except in position ? Draw one member of each set if there is 

 a difference. 



Examine one of the floral leaves under the lens with transmitted 

 light, shading meanwhile from direct light, to discover any venation. 

 If any is found indicate this on the drawing. 



The leaflike organs together are the perianth. When in two dis- 

 tinct sets, the outer set is the calyx, the members being the sepals ; the 

 inner is the corolla, made up of petals. 



