MORPHOLOGICAL DEVELOPMENT. 



found some in which conformity to the general law is not 

 obvious. The discussion of these apparent anomalies would 

 carry us too much out of our course. A clue to the expla 

 nation of them will, I believe, be found in the explanation 

 presently to be given of certain kindred anomalies in the 

 forms of individual flowers. 



233. The radially-symmetrical form is common to all 

 individual flowers that have vertical axes. In plants which 

 are practically if not literally uniaxial, and bear their flowers 

 at the ends of upright stalks, so that the faces open hori 

 zontally, the petals are disposed in an all-sided way. Cro 

 cuses, Tulips, and Poppies are familiar examples of this 

 structure occurring under these conditions. A Ranunculus 

 flower, Fig. 228, will serve as a typical 

 one. Similarly, flowers which have 

 peduncles flexible enough to let them 

 hang directly downwards, and are not 

 laterally incommoded, are also radial; 

 as in the Fuchsia, Fig. 229, as in Cycla 

 men, Hyacinth, &c. These relations of 

 form to position are, I believe, uniform. Though some flowers 

 carried at the ends of upright or downright stems have 

 oblique shapes, it is only when they have inclined axes or 

 are not equally conditioned all round. Xo solitary flower 

 having an axis habitually vertical, presents a bilateral form. 

 This is as we should expect ; since flowers which open out 

 their faces horizontally, whether facing upwards or down 

 wards, are, on the average, similarly affected on all sides. 



At first it seems that flowers thus placed should alone be 

 radial; but further consideration discloses conditions under 

 which this type of symmetry may exist in flowers otherwise 

 placed. Remembering that the radial form is the primitive 

 form that, morphologically speaking, it results from the 

 contraction into a whorl, of parts that are originally arranged 

 in the same spiral succession as the leaves ; we must expect 



