CLASS DIDYNAMIA. 



171 



lyx or perianal ; 2d, with a perianth. In the first section \vc find 

 several interesting native plants. The Clematis or Virgin's bower 

 is a beautifiil climbing plant, which supports itself by winding its 

 petiole or leaf-bearing"stems around other plants; the flowers are 

 white arid clustered in corymbs ; the seed has a long silk-like 'iungc, 

 which gives it a fine appearance after the blossoms have faded. 

 This plant contains many species, and is cultivated both in this 

 country and in Europe. At fig. 136, a, is a flower of the Clematis; 

 b. represents its receptacle with numerous styles proceeding from it, 

 and the petal and stamens separated, showing them to be inserted 

 upon the receptacle. 



The Hellebore (Helleborus) is an exotic much spoken of by clas- 

 sical writers. Hippocrates, one of the most ancient physicians, 

 remarked upon its qualities; it grew about Mount Olympus, and was 

 early known as a very poisonous plant. 



The MagnoUa and Tulip-tree are among the most splendid trees 

 of North America; they are said also to be common to China. 

 The region of the Magnolia grandiflora extends from South Caro- 

 lina to the isthmus of Darien. In some cases these trees rise to the 

 height of 90 feet before sending off any considerable branches ; the 

 spreading top is then clothed "with deep green, oblong-oval leaves, 

 like a laurel ; these are, at most seasons, enlivened by large and 

 fragrant white flowers. 



The class Polyandria, though not important for its fruits, con- 

 tains some valuable medicinal plants, besides those which we have 

 noticed. 



LECTURE XXXII. 



CLASS DIDYNAMIA AND TETRADYNAMIA. 



The two classes which are to afford subjects for our present ob- 

 servations, are founded upon the number and relative length of the 

 stamens. In distinguishing their orders, the number of styles is not 

 regarded, but new circumstances of distinction are introduced, viz. 

 the seeds being enclosed in a pericarp, or 

 destitute of this covering, and the compar- 

 ative length of pods. 



CLASS XIII. — DIDYNAMIA. 



This class has flowers with 4 stamens, two of 

 which are longer than the other two ; the 

 stamens stand in pairs ; the outer pair be- 

 ing longer, the inner pair shorter and con- 

 verging. 



The class contains two orders, Gymnos- 

 permia, (seeds naked or without a pericarp,) 

 and Angiospermia, (seeds enclosed in a per- 

 ricarp.) 



The labiate flowers are found in this class ; these are monopeta- 

 lous, and irregular in their outline. The term labiate is derived 

 from the Latin labia, signifying Ups ; the" flowers being divided at 

 the top into two parts, resembling the lips of an animal. This tribe 



Clematis— Hellebore— Magnolia— What classes are now considered 1— How ara 

 their orders distinguished 7— L abiate flowers. 



