DEVELOPMENT OF PLANTS 



441 



The parts of the perianth, which are more frequently in threes 

 or indefinite in number than in fives, are also subject to consider- 

 able variation. Very frequently the corolla is not developed or 

 partially suppressed, and the sepals become colored and petaloid, 

 as in the marsh marigold, hepatica, certain windflowers, rue, 

 spice bush, larkspur, etc. In a few of the genera the perianth 

 becomes greatly modified and even irregular, as in the columbine 

 (Fig. 306, B, n), where five of the petals, often regarded as 

 modified stamens, are transformed into tubular honey leaves or 



n 



7 



FIG. 307. Highest type of the Ranales: A, inflorescence of monkshood. 

 B, section of a flower s, helmet-like sepal enclosing nectar organ, n. C, 

 flower of larkspur. D, section of flower s, spurred sepal enclosing two- 

 spurred nectar organs, n. E, fruit of larkspur consisting of 3 pistils maturing 

 as follicles. 



into spurs and hoods, as in the larkspur and monkshood (Fig. 

 307, B, D). These flowers illustrate very well the progressive 

 coloration that is often associated with the variation of the peri- 

 anth. The simpler forms are usually yellow or white, while 

 flowers with more highly modified parts are pink and pale blue 

 (columbine), blue in higher types (larkspur) and ultra-marine 

 blue in the most irregular and highly modified type (monks- 

 hood) . Any of these flowers may take on by reversion the lower 

 29 



