424 RELA TION TO ENVIRONMENT. 



upper lobes are sharph' separated from the three lower forming 

 two "lips." The labiate corolla of the toadflax, or snapdragon 

 is personate, or masked, because the lower hp arches upward 

 like a palate and closes the entrance to the corolla tube; that of 

 the dead nettle (Lamium) is ringent or gaping, because the hps 

 are spread wide apart. In some plants the labiate corolla is not 

 very marked and differs but slightly from a regular form. 



The ligidate or strap-shaped corolla is characteristic of the 

 flowers of the dandelion or chicory, or of the ray flowers of other 

 composites (fig. 451). The lower part of the gamosepalous 

 corolla is tubular, and the upper part is strap-shaped, as if that 

 part of the tube were split on one side and spread out flat. 



These forms of the flower should be studied in appropriate 

 examples. 



813. TTnion of flower parts. — In the buttercup flower all the 

 parts of each series are separate from one another and from 

 other series of parts. Each one is attached to the receptacle of 

 the flower, which is a very much shortened portion of the flower 

 axis. The calyx being composed of separate and distinct parts 

 is said to be polysepaloiis, and the corolla is likewise polypetal- 

 ous. The stamens are distinct, and the pistils are simple. In 

 many flowers, however, there is a greater or lesser union of parts. 



814. Union of parts of the same series or cycle. — The parts 

 coalesce, either slightly or to a great extent. Usualh- thev are 

 not so completely coalesced lait what the number of parts of 

 the series can be determined, ^^'here the .sepals are united the 

 calyx is gamosepalous, ■\\'hen the petals are united the corolla is 

 gamopetalous. 



Union of the sepals or of the corolla is Cjuite common, but 

 union of the stamens is rare exce])t in a few families where 

 it is quite characteristic. When the stamens arc united by 

 their anthers, they are syngcna-sious. Tliis is the case in 

 most flowers of the composite fami]\-. When all the stamens 

 are united into one group b^- their filaments, tliev are jiinua- 

 delphoiis (one brotherhood), as in hol}hock, liibiscus, cotton 



