302 



BOTANY: PRINCIPLES AND PROBLEMS 



poorl}^ developed, or have their various members entirely separate 

 from one another, and the Syrnpetalae, in which the petals arc 

 tj^pically united into a gamojietalous corolla. 



Of the great array of groups which compose the dicotyledons 

 we shall mention only the most important. The Archichlamy- 

 deae include, among others, the following orders: 



Amentiferae. — This group is now commonly divided into a 

 number of subordinate orders, but in its larger sense it includes 

 the oaks, beeches, chestnuts, hickories, walnuts, birches, alders. 



Fig. 2.33.— One of the Ranales. 

 Hepatica (Hepatica triloba), belonging 

 to the family Ranunculaceae. 



Fig. _':il ■ the Resales. 



Choke cherrj- irruutis virginiana) , 

 belonging to the family Rosaceae. 



willows, poplars, and many others, all of them trees or shrubs. 

 The perianth is scale-like or absent, the flowers dry and chaffy 

 and arranged in a long, sometimes cone-like inflorescence, the 

 ament or catkin (Fig. 107). They are prevailingly wind-polli- 

 nated. These plants were long regarded as the most ancient of 

 the dicotyledons, but are now looked upon by many botanists 

 as simplified and reduced forms. 



Ranales (Fig. 233). — This great and varied group contains the 

 buttercup, magnolia, laurel, and water-lily families and their 

 allies, including trees, shrubs, and herbs. Its flowers are polli- 

 nated by insects and are primitive in the sense that their parts, 



