THE FLOWEE. 



89 



Fig. 157. 



surface above, its centre corresponds, of course, to the apex ; and 

 we may thus say that the above-named organs succeed each other 

 from without inwards, or from below upwards. 



The accompanying diagram of the floral 

 whorls (fig. 157) illustrates the theoretical con- 

 struction of a perfect and symmetrical flower. 

 Here the internodes are imagined to be deve- 

 loped between the separate circles of the flower 

 an arrangement which does occasionally occur 

 in nature, as in Capparids, Passion-flowers, &c. 



Anterior and Posterior portions of the 

 Flower. All axillary flowers arise in the 

 angle between a bract or leaf and the stem ; 

 from this is taken the rule as to the relative 

 position of organs in describing flowers. 

 The side of the flower next the stem is 

 the upper or posterior part, that next the 

 bract the anterior or lower ; and in the dia- 

 grams or ground-plans used to represent 

 the construction of flowers, it is impor- 

 tant to mark the places of the axis and the 

 bract, the former being represented behind 



by a O? the latter in front by an X Or ' . ', 



as in fig. 160. 



Where flowers are solitary and terminal there is no proper back and front ; 

 but in plans of these, the position of the last leaf or bract, and specially of 

 the bracteoles, should be shown. If, with a flower of four sepals, there is 

 a pair of bracteoles, the two lowermost sepals are antero-posterior (fig. 167, 

 p. 96) ; but if there are two pairs of bractlets, the two uppermost sepals 

 are antero-posterior. When bracts are suppressed, as in the Cruciferce, 

 the position of the floral organs may be determined by their relation to 

 the parent stem. 



Arrangement of Parts. The parts of flowers being phyllomes, 

 their arrangement corresponds to that of stem-leaves. [Sometimes 

 they are truly whorled, while at other times, especially in the 

 calyx and corolla, they are arranged in spiral cycles, and are 

 developed successively on the ^ or -f plan, but reduced into apparent 

 whorls by the absence of internodes. Such flowers are called 

 acyclic-, and where some of the parts of the flower are arranged 

 spirally and others in a verticillate manner, the term hemicydic is 

 given. 



In such a calyx as that of the Kose, the sepals are imbricated on 

 the f plan (figs. 158-160). In the ternary floral envelopes of many 

 Monocotyledons we find illustrations of the type. Sometimes the spiral 



parated by internodes. 



