174 STUDY OF COMMON PLANTS. 



XXIV. THE ROSE FAMILY. KOSACEJE. 



MATERIAL REQUIRED. 



Flowering shoots of the cultivated cherry, and, as soon as they are 

 in full bloom, those of the peach, plum, apple, and pear. 



Representatives of the following genera, as far as they can be ob- 

 tained in flower or fruit; Fragaria, Physocarpus, Potentilla, Geum, 

 Rubus, Rosa, Crataegus. 



THE CHERRY. Prunus Cerasus, L. 

 Distribution. 



The cultivated cherry is familiarly known in the north 

 temperate zone of both hemispheres. For the evidence 

 regarding the region to which it is indigenous, see De 

 Candolle, Origin of Cultivated Plants, pp. 206-210. 



Flower and Fruit. 



I. Study the parts of the flower in succession, noting 

 their form and insertion, the union of parts, and other 

 modifications if such exist. 



II. Make a longitudinal section and draw it accurately, 

 Is any nectar to be found ? If so, are there any arrange- 

 ments for its protection ? 



III. Make longitudinal sections of a number of ovaries 

 and transverse ones of others. Determine the number of 

 ovules, their form and place of attachment. Draw. Com- 

 pare the number of ovules in flowers just opened and in 

 those that are fading or have lost their corolla. 



