THE WATER-LILY FAMILY. 8i 



carry the peas. Then let them be compressed till their 

 sides are in contact together. Now imagine them as 

 grown together by their sides as in (5). 



If the whole were now cut across, sLx chambers 

 would be seen with two rows of peas on the " marginal 

 placentas," forming the inner angles of the ovary-cells. 

 They then thus would form a syncarpous pistil. 



There may be any number of carpels, but two, 

 three, four, and five are the commonest among flowers. 

 In the Water-lily the ovules are in a somewhat 

 exceptional position, being all over the sides of the 

 divisions, and not exclusively in the angles. 



The circular leaf, so characteristic of this family, is 

 seen also in some other aquatic plants not belonging 

 to this order, and it also occurs in some marsh plants 

 which were probably once aquatic, as Ranun'cuhis 

 Mey'cri ^ and Hyclrocot'yle verticilla'ta.^ 



If the petiole of a leaf, or the flower-stalk of the 

 Water-lily, be cut across, and then slightly wetted with 

 Indian ink, good impressions can be made on paper 

 showing the long Laciince, or " air-chambers," always to 

 be found in submerged plants. It is the air in these 

 hollow tubes which enables the flower-stalks and 

 petioles to stand erect in the water. It \vill be also 

 noted how feeble is the wood in all submerged stems. 

 The reason is that stems growing in the air have to 



^ Found at Kat-berg. 



2 An " Umbellifer " occurring in wet places near Cape Town. 



