628 MANUAL OF POISONOUS PLANTS 



plants. A variety of Tunicra diffusa furnishes a laxative. The Datisca cauva- 

 bina of Southern Europe belongs to the family Datiscaceae and furnishes the 

 yellow coloring matter datiscin used to dye silk; some members of the family 

 Dilleniaceae are cultivated for their beautiful flowers. The Marcgraviaceae are 

 occasionally cultivated and the Marcgravia unibelhta is used in medicine; the 

 family also contains the "Bitter-sick tree" Datisca glovierata which is used, ac- 

 cording to Chesnut, by the Indians of California to poison trout. 



Families of Parietales 

 Calyx gamosepalous. 



Throat of the calyx with a fringed crown Passifloraceae. 



Throat of calyx without a crown Loasaceae. 



Calyx with sepals; sepals generally distinct and persistent. 



Flowers irregular Violaceae. 



Flowers regular. 



Trees or shrubs ; leaves alternate Theaceae. 



Herbs or shrubs; leaves opposite or whorled Hypericaceae. 



Theaceae. Tea Family 



Trees or shrubs with alternate simple leaves without stipules; flowers large, 

 showy, regular, hypogj'nous, mostly axillary; sepals 5, or rarely more, often with 

 2 bracts; petals 5 or rarely more; stamens more or less monadelphous ; anthers 

 2-celled; ovary 2-5-celled; ovules 2 or more in each cell; fruit a woody capsule; 

 embryo large; endosperm scant. A small order of 160 species, mostly native 

 of warm regions. The tea plant (Camellia Thea) is native to Assam, and ex- 

 tensively cultivated in Japan, China, and India. The Thea sinensis with the 

 varieties viridis and bohea furnish tea. Successful attempts at cultivation have 

 also been carried on in South Carolina. The black and green teas come from the 

 same species. Tea is an important article of commerce in all civilized countries, 

 Russia, England and the United States using large quantities. 



The active principle found in tea is caffein or thein CgH^^N^O^, a feebly 

 alkaline, bitter alkaloid which is a cerebral and cardiac stmiulant. Thea also 

 contains the alkaloid caffeidin C,H,„N,0; theophyllin C.H,,N,0,+H,0 ; theo- 

 bromin C^HgN^Og, which is a bitter alkaloid having a physiological action sim- 

 ilar to that of ihein. The principle alkaloid thein, or caffein, as it is known, is a 

 feebly basic, proximate substance, obtained from the tea plant, from the dried 

 seeds of coffee, and from some other plants. This alkaloid has no particular 

 action upon the digestive tract, unless it is used in large quantities, when it 

 may cause gastro-intestinal irritation. Caffein increases the blood pressure, 

 causing the heart to beat more forcibly and rapidly. It is a certain and direct 

 stimulant. It produces wakefulness and restlessness and stimulates the reason- 

 ing and imaginative faculties in man. In the lower animals, according to Dr. 

 Winslow, it often causes "the most intense cerebral excitement and mania 

 when given in large doses, — produces restlessness, increased reflex excitability 

 and convulsions in the lower animals." Dr. Winslow states further that caffein 

 is a spinal and muscle poison to the frog, and tetanic convulsions occur in the ba- 

 trachian similar to those produced by strychnin, but there is also muscular rigid- 

 ity. The symptoms of poisoning in dogs, cats, and mammals generally, are rest- 

 lessness, occasionally vomiting in dogs, rapid breathing, primary reduction fol- 

 lowed by rise in temperature, clonic or tonic convulsions, muscular weakness, and 



