558 BOTANY AND PHARMACOGNOSY. 



Descrii'tion. Imbricated, numerous, usually in small cones; 

 petals broadly ovate, the upper part rose-colored and retuse, the 

 lower part brownish-red, more or less rounded, acute or trun- 

 cate, with numerous papillae and fine longitudinal veins; texture 

 velvety ; odor agreeable ; taste astringent and slightly bitter. 



Constituents. Volatile oil in small amount ; a yellow, crys- 

 talline glucoside quercitrin, which yields, on decomposition, quer- 

 cetin; tannin and gallic acid. The coloring principle is .soluble 

 in water and alcohol and gives a deep yellowish-red color with 

 acids; a green color changing to brown with alkalies; purple or 

 violet with potassium alum or iodine solutions; and a deep blue 

 with ferrous or ferric salts. 



Allied Plants. The petals of Rosa ccntifolia are collected 

 after the expansion of the flowers and dried ; they are brownish 

 and not so fragrant as those of Rosa gallica. The flowers of 

 cultivated plants of Rosa damascena yield the commercial volatile 

 oil of rose (p. 289). 



ZEA. CORN SILK. The fresh styles and stigmas of Zca 

 Mays (Fam. Gramineae), an annual plant indigenous to tropical 

 America and known only in cultivation, being cultivated widely 

 in nearly all tropical, sub-tropical and temperate regions (p. 228). 



Description. In matted masses consisting of several hun- 

 dred or more slender, very delicate, thread-like, purplish-red to 

 greenish-white, more or less translucent styles; 10 to 20 cm. 

 long; stigmas bifid, slender, 2 to 3 mm. long; slightly odorous; 

 taste insipid. 



When viewed under the microscope the upper part of the 

 styles and the stigmas are seen to have numerous multicellular, 

 non-glandular hairs from 0.2 to 0.5 mm. long, among which are 

 numerous spinose pollen grains 10 to 15 /x in diameter. 



Constituents. Not much is known concerning the constit- 

 uents of this drug, and the analyses have been chiefly of the dried 

 commercial article. The fresh drug contains about 83 per cent, 

 of water. The dried drug contains a volatile alkaloid ; two resins 

 about 5.5 per cent. ; a crystalline principle, maizenic acid, about 

 1.25 per cent.; fixed oil, 5.25 per cent.; sugar; ash, about 12 per 

 cent. The coloring principle of the fresh drug is soluble in water 

 and alcohol and is changed to yellowish-red with acids, green 



