CLASSIFICATION OF ANGIOSPERMS. 597 



occidental, a shrub growing in tropical America. A principle 

 resembling cardol is found in the East India Marking tree or Ink 

 tree(Sctnccarpus .inacardium)and Holigarna ferruginea of India. 



The POISON SUMAC or Poison Elder (Rhus Vernix) is a shrub 

 or small tree found in swamps in the United States and Canada. 

 The leaves are 7- to I3~foliate, with obovate or oval, acuminate, 

 entire leaflets ; the flowers are small, green, and in axillary pani- 

 cles; the fruit resembles that of R. radicans (Fig. 328). The 

 plant is poisonous like R. Toxicodendron and probably contains the 

 same principle. Other species of Rhus are also poisonous, as the 

 western Poison Oak (R. diversiloba) of the Pacific Coast, and 

 the Japanese Lacquer or Varnish tree (R. vernicifera and R. 

 succedanea). The lacquer trees grow wild in both China and 

 Japan, where they are also cultivated. The lac is obtained by 

 incising the bark and removing it with a pointed spatula. The 

 grayish-white emulsion is strained and on exposure to air it 

 changes to brown, becoming finally black. This change is due to 

 the oxidizing enzyme laccase. The natural lac (Kiurushi) contains 

 a non-volatile poisonous resin-like principle and is closely associ- 

 ated with other resinous substances. Japanese lac is thinned with 

 camphor, or mixed with linseed oil, and on drying in a moist atmos- 

 phere forms the most indestructible varnish known. Various pig- 

 ments are used, as vermilion, gamboge, acetate of iron and other 

 substances. The best glossy black colors are obtained by the 

 addition of iron. 



Rhus glabra or the Scarlet Sumac is a smooth shrub. The leaves 

 are n- to 3i-foliate,the leaflets being lanceolate, acuminate, sharply 

 serrate, dark green above and lower face glaucous ; the flowers are 

 greenish, polygamous and in terminal panicles ; the fruits of this 

 plant and of R. typhina (Fig. 329) are used in medicine. 



CHINESE GALLS are excrescences produced on Rhus semialata 

 as a result of the stings of an Aphis. JAPANESE GALLS are similar 

 formations occurring on Rhus japonica. (See pp. 206, 334.) 



Pistacia Lentiscus is a shrub or tree, which is found growing 

 in the Grecian Archipelago. The leaves are pinnately compound 

 and with winged axis, the leaflets being alternate, oblong, entire, 

 sessile; the flowers are small, dioecious, and in axillary clusters. 

 In the bark of this plant there are large cavities which contain 



