26o BOTANY AND PHARMACOGNOSY. 



IX. ORDER ARISTOLOCHIALES. 



This order includes two families which are very different in 

 their general habits, (a) The Rafflesiaceae are parasitic herbs 

 that are almost devoid of chlorophyll. The reddish vegetative 

 parts penetrate into the tissues of the host and from these arise 

 almost mushroom-like flowers which in the case of RaMesia 

 Arnoldii of Sumatra are i M. in diameter, being probably the 

 largest flowers known. The plants of this family are rich in 

 astringent substances. 



b. ARISTOLOCHIACE.E OR BIRTHWORT FAMILY. 

 The plants are non-parasitic herbs or shrubs, some of which are 

 twining. The leaves are simple and in many of the plants more 

 or less cordate and reniform. The flowers are perfect and the 

 perianth is 3- to 6-lobed. While the flowers of our native species 

 are rather small and insignificant those of the tropical plants 

 are extremely curious, being generally of some striking color and 

 of various odd forms. 



Aristolochia reticulata is one of the plants that furnishes the 

 official drug serpentaria (p. 501). From a slender rhizome with 

 numerous hair-like roots, arise one or more short, leafy branches 

 which are more or less simple, somewhat hairy, and bear oblong- 

 cordate, prominent-reticulate, hairy leaves (Fig. 137). The 

 flowers are borne on slender, scaly, basal branches ; the calyx tube 

 is purplish and curved like the letter " s," being enlarged around 

 the ovary and at its throat. The fruit is a capsule containing 

 numerous flat or concave seeds. An allied species Aristolochia 

 Serpentaria furnishes the drug Virginia snakeroot. It is a more 

 delicate plant, the leaves being ovate-lanceolate, acuminate; the 

 flowers are solitary, and in some cases cleistogamous. This spe- 

 cies is found growing in the United States, more especially east 

 of the Mississippi, while Aristolochia reticulata is found west of 

 -the Mississippi from Arkansas to Texas. The plants of this genus 

 contain volatile oils and in addition to the two species mentioned 

 forty-five other species are used in medicine in varous parts of 

 the world. 



Asarum canadense (Canada snakeroot or wild ginger) is a 

 plant common in the Northern United States and Canada (Fig. 



