MORPHOLOGY OF HIGHER PLANTS. 215 



The tissues of the ovary arc, as a rule, in a very rudimentary 

 condition ; in fact, so rudimentar^ that it is difficult to distincuish 

 the ovaries of two flowers that develop into quite different fruits. 

 In some instances it is said that notwithstanding tlie subsequent 

 changes, each cell of the fruit is already indicated in the ovary. 

 The ovary possesses an outer and an inner epidermis ; the outer 

 is provided with stomata and may also possess hairs ; the inner 

 may also have stomata and after fertilization may develop secre- 

 tion hairs, as in the orange. Between the epidermal layers occur 

 thin-walled parenchyma cells which contain leucoplastids and 

 chloroplastids, and in which the fibrovascular bundles are dis- 

 tributed, these being usually simple, or complex, as in the pea. 

 The number of fibrovascular bundles is more or less dependent 

 upon the number of carpels that make up the gynsecium ; as a 

 rule, there is a strong fibrovascular bundle which corresponds to 

 the midvein of each carpel. 



The PLACENTA is a development from the inner epidermis. It 

 is traversed by a fibrovascular bundle from which branches arc 

 given ofT to the individual ovules ; it may have a conducting tissue 

 similar to that found in the st3de, and in some cases the epidermis 

 of the stalk of the ovule may be developed to. a stigma-epithel. 



The OVULE not only possesses a distinct form as already given, 

 but the internal structure, by reason of the changes associated with 

 fertilization, is more or less characteristic for certain species and 

 genera. It has an epidermal layer, the outer walls of which are 

 more or less cutinized, and it consists for the most part of paren- 

 chyma cells rich in protoplasm and food-materials ; in addition the 

 embryo-sac contains a number of nuclei. The stalk and raphe are 

 connected with the placenta by means of a fibrovascular bundle. 



The NECTAR may be secreted by certain* of the epidermal cells 

 of various parts of the flower; these may resemble the ordinary 

 epidermal cells or they may be modified to papillae, as in the 

 spurred stamens of the violets, or to hair-like processes, as in 

 Malva. The cells which secrete nectar constitute the " nectar- 

 apparatus," and the walls are usually thin and more or less cutin- 

 ized. The nectar-apparatus is found more generally upon some 

 part of the stamen, but the sepals and petals are not infrequently 

 saccate or spurred, which adapts them for holding the nectar. 



