334 BOTANY AND PHARMACOGNOSY. 



XX. ORDER PARIETALES. 



This is a group of plants of rather wide distribution, and 

 includes perennial herbs like the iwolets; evergreen shrubs, such 

 as the Tea plant ; and vines like the Passion flower. As the name 

 indicates the plants of this order are characterized by the flowers 

 having, for the most part, ovaries with parietal placentas. 



a. FAMILY DILLENIACEiE.— The plants are mostly trop- 

 ical trees which yield valuable timber. The wood of a species of 

 Dillenia growing in the East Indies also contains red coloring sub- 

 stances. The fruits of Dillenia indica contain citric acid and are 

 used like lemons. The leaves of Curatella americana contain con- 

 siderable silicon and are used to polish wood. Dillenia speciosa of 

 India contains a large percentage of tannin. Some species of 

 Dillenia are cultivated and the foliage and flowers combine to 

 make the plants the most beautiful in the plant kingdom. 



b. MARCGRAVIACEJil.— The members of this family are 

 partly epiphytic, and have dimorphic leaves, the smaller ones being 

 pitcher-like. The plant which is cultivated in greenhouses, Marc- 

 gravia nmbellata, is used in the Antilles in medicine. 



c. THEACE^ OR TEA FAMILY.— The plants are shrubs 

 or trees with alternate, evergreen leaves, and perfect, regular 

 flowers with numerous stamens, occurring one or more in the 

 axils of the leaves. The fruit is a 3- to 5-locular, dehiscent capsule. 

 The most important member of this family is Thea sinensis, the 

 two varieties viridis and Bohea furnishing the leaves known as 

 TEA. The Tea tree is indigenous to Eastern Asia, and is now 

 extensively cultivated in China, Japan, India, Java, Brazil, Sicily, 

 Portugal and France, and to some extent in the Southern United 

 States. 



The fresh leaves of Thea do not have the properties which 

 characterize the commercial article, the aroma and other qualities 

 being developed after special treatment. Two general classes of 

 tea are found in commerce, these depending on the mode of treat- 

 ment. Those which are rapidly dried by means of artificial heat 

 constitute Green tea. The leaves which are slowly dried, per- 

 mitting fermentation to set in, furnish Black tea. Tea leaves 

 contain 1.5 to 3.5 per cent, of caffeine; theobromine and the- 



