MONOCLINOUS AND DICLINOUS FLOWERS 87 



correspond with the number of carpels present in the latter, as 

 dissepiments occur which are not formed from the united walls 

 of two neighbouring carpels but which are produced by the 

 growth inwards of a portion of the ovary wall. The latter are 

 termed false dissepiments, an example of which is the septum 

 which divides the ovary in the Cruciferae. 



8. Placentation. — The arrangement of the placentas or points 

 from which the ovules arise inside an ovary is termed placentation. 

 When the ovules are arranged in lines on the wall of the ovary, 

 as at 3, Fig. 38, the placentation \^ parietal. 



In multilocular ovaries, such as at 4, Fig. 38, the ovules are 

 generally arranged in the angles formed at the centre where 

 the edges of the carpels are united, and the placentation is 

 described as axile. 



In the primrose and chickweed families of plants the ovules 

 are attached to a placenta which arises in the form of a short 

 column from the base of the ovary and has no connection with 

 the sides : this arrangement is known as free central placentation. 



9. Monoclinous and diclinous flowers : monoecious and 

 dioecious plants. — When both the essential parts are present in 

 the same flower, as in the buttercup, charlock, and the majority 

 of common plants, the flower is described as motioclinous ; some- 

 times the terms perfect, hermaphrodite or bisexual are applied to 

 such flowers. 



In certain flowers, as those of the cucumber, melon, hop, 

 hazel, and willow, one or other of the essential parts are 

 missing : such are said to be diclinous, imperfect or unisexual. 

 Diclinous flowers may be of two kinds, namely, (i) those in 

 which the androecium is alone present and described as staminate 

 or male flowers, and (2) those in which only the gynsecium is 

 met with and spoken of as carpellary, pistillate ox Jemale flowers. 



When both kinds of diclinous flowers are met with on the 

 same individual plant, as in the case of the cucumber and hazel, 

 the plant is said to be monoecious ; in examples, such as the hop 



