ORIENTATION OF THE PARTS 201 



from the central axis, so that the flowers face upwards 

 and outwards. We find too that in C^ESALPINIA and 

 POINCIANA, the largest (the curved spoon-shaped) sepal 

 stands always on the lower and outer side, and the 

 smallest (in C^ESALPINIA tubular) petal stands exactly 

 opposite it on the upper and inner side. Or if we 

 imagine ourselves in the flower, facing like it out- 

 wards, we may call the upper, inner side, the back 

 or posterior side, the lower, outer side, the front or 

 anterior. 



We learn then that these flowers have not only a 

 definite number of parts, but also a definite posterior 

 and anterior side, the former being the upper and near- 

 est the central axis, the latter the lower and furthest 

 from it. 



If there were only one flower, facing directly up- 

 wards at the end of an upright single stem, it would 

 have no back or front, all the sides being similar. 

 This is the case for instance with the Sacred-lotus 

 and other Water-lilies. 



2. Now take a flowering branch of ERYTHRINA 

 INDICA. The flowers are borne, on short pedicels 

 one above the other along an upright axis, so that 

 the first to open are the bottom ones, the youngest 

 being at the top. The arrangement is the same as 

 in C^ESALPINIA, POINCIANA, and most CASSIAS, and 

 is a raceme. Each flower is at first enclosed in 

 a green covering, which splits open as the flower 

 unfolds and takes the place of the separate sepals 

 of C^ESALPINIA. As in the latter, the flowers when 

 fully open, face side ways, away from the main axis. 

 The most conspicuous part of each flower is the 



