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A TEXTBOOK OF THEORETICAL BOTANY 



Red Admiral, Peacock, Painted I^ady and Tortoiseshell butterflies to the 

 bushes. 



Fig. 1789. — Biiddleia davidi (B. 

 variabilis). Long inflorescence 

 of mauve flowers. 



Fig. 1790. — Buddleia ^lobosa. Globular 

 inflorescence of orange flowers. 



The second important genus is Strychnos, which contains about 200 

 species, widespread in the tropics. S. nux-vomica is an erect tree, occurring 

 in India and Ceylon. The fruits yield the alkaloids strychnine and brucine. 

 iS. ignatia produces seeds known as Ignatius Beans, which are used in 

 India as a remedy for cholera. S. toxifera is the source of Curare poison, 

 which is used by the South American Indians to poison their arrows. It is 

 obtained from the bark by scraping and maceration in water. The seeds of 

 S. potatorum are used to purify dirty water for drinking. They are rubbed 

 on the inside of the vessel and cause precipitation of colloidal matter in 

 suspension. 



While some of the species are trees, others are climbing shrubs with 

 hooked tendrils which are modified axillary shoots. If the hook becomes 

 attached to a support it thickens after closing around it and then becomes 

 lignified. Other species have axillary thorns. Gehemiiim sempervirens, 

 which is found in south-eastern United States, contains the alkaloid 

 gelsemin in its rootstock. 



The Gentianaceae are another rather small family with seventy 

 genera containing about 800 species. They are mostly annual or perennial 

 herbs (Fig. 1791), with opposite leaves and cymose inflorescences. Many 

 perennate by underground rhizomes. Many of the species are found in 



