378 BOTANY AND PHARMACOGNOSY. 



Quite a number of the plants of the Acanthaceae are used in 

 the Tropics in medicine. One of these, Adhatoda vasica of trop- 

 ical Asia, contains the alkaloid vasicine, and is said to have, the 

 property of destroying algae which grov^r in the rice swamps. 



k. PLANTAGINACE^ OR PLANTAIN FAMILY.— The 

 plants are annual or perennial herbs, represented by but few 

 genera, but numerous species. The principal genus is Plantago, 

 which includes 200 species that are widely distributed. Several 

 species of Plantago are used in medicine. The common plantain 

 (Plantago major) contains a bitter principle and a resin. The 

 short rhizome contains considerable starch. The seed-coat has 

 an outer mucilaginous layer, and the mucilage of the seeds of 

 Plantago psyllium, P. areimria (both of Europe) and P. ispaghnl 

 (of the East Indies) is used as a sizing material. The seeds of a 

 number of the species of Plantago are used as bird food, partic- 

 ularly for canaries. 



V. ORDER RUBIALES. 



The plants of this order are distinguished from all of the 

 preceding Sympetalas by having flowers which are distinctly 

 epigynous. The leaves are opposite or verticillate. 



a. RUBIACE^ OR MADDER FAMILY.— The plants are 

 herbs, shrubs or trees, and of the representatives found in the 

 United States the following may be mentioned : Bluets (Hous- 

 tonia species), Partridge-berry {Mitchella re pens) and Bedstraw 

 {Galium species). In Mitchella and Houstonia the flowers are 

 dimorphic. 



Cinchona species. — The plants are mostly trees, or rarely 

 shrubs, with elliptical or lanceolate, entire, evergreen, petiolate, 

 opposite leaves (Fig. 177). The flowers are tubular, rose-colored 

 or yellowish-white, and occur in terminal racemes. The fruit is 

 a capsule, which dehisces into two valves from below upward, 

 the valves being held above by the persistent cahx. The seeds 

 are numerous and winged. There are from 30 to 40 species of 

 Cinchona found growing in the Andes of South America at an 

 elevation above 800 M. and in a restricted area about 500 miles 

 in length extending from Venezuela to Bolivia. The plants are 



