CLASSIFICATION OF ANGIOSPERMS. 595 



bling picrotoxin, known as coriamyrtin, which is also found prob- 

 ably in C. atropurpurea of Mexico. The leaves of Coriaria myrti- 

 folia or TANNER'S SUMAC are coriaceous, distinctly 3-nerved, 

 astringent and bitter and were at one time substituted for senna 

 leaves. A black dye is obtained from C. nisei folia of New Zealand 

 and Chile. While the fruits of some species are quite poisonous, 

 the sap of the fleshy leaves is used in New Zealand in making 

 an intoxicating drink. 



c. ANACARDIACE^: OR SUMAC FAMILY. The plants 

 are trees or shrubs with an acrid, resinous or milky latex, and 

 alternate leaves. 



Rhus Toxicodendron, POISON IVY or Poison Oak, is a woody 

 vine, climbing by means of aerial roots and sometimes becoming 

 quite shrub-like, which is common along roadsides in the United 

 States. The leaves are 3-foliate, the leaflets being ovate, acumi- 

 nate, nearly entire, inequilateral and with short stalks ; the flowers 

 are green and in loose axillary panicles ; the fruit is a globular, 

 glabrous, grayish drupe (Fig. 328). The nature of the poisonous 

 constituents of Poison Ivy is not definitely known. It was orig- 

 inally considered to be in the nature of a volatile principle. Pfaff 

 and his pupils seemed to show that the poisonous principle was a 

 non-volatile brownish-red resin which is soluble in alcohol and 

 called toxicodendrol. Schwalbe, on the other hand, states that 

 the poisonous substance is of a volatile nature, being formed in the 

 laticiferous vessels and by osmosis is transferred to the hairs. 

 The poison may be transmitted either by direct contact with the 

 hairs, much as in the same manner with the nettles, or by volatiliza- 

 tion of the oil when the hairs are broken. The experience of most 

 plant collectors would seem to indicate that in Poison Ivy there 

 is a volatile toxic constituent (Amer. Jour. Pharm., March, 1914). 

 On the other hand, Rost and Gilg were unable to find a volatile 

 poison in either the hairs or pollen of Poison Ivy. In some ex- 

 periments conducted by Warren on pollen grains, similar negative 

 results were obtained (Aincr. Jour. Pharm., Dec., 1913). The 

 poisonous principle occurring in several species of Rhus is an 

 amber-red, non-volatile liquid. It is of a resinous nature, com- 

 bining with the alkali hydroxides to form nigrescent compounds, 

 and otherwise behaves like certain phenolic compounds. The toxic 



