THE FLAVONES OF RHUS 
Perkin has isolated flavones from Rhus Coriaria,'^ R. Metopium^ 
(= Metopium Metopium (L.) Small), R. Cotinus^ (= Cotinus Coggyria 
Scop.), and R. rhodanthema F. v. M.^ (= Rhodosphaera rhodanthema 
(F. V. M.) Engl.). Only in the last two does the wood contain a 
flavone, and in both cases it is fisetin. In the leaves of the first two, 
the leaf flavone is myricetin, in the third both myricetin and quercetin 
occur, and in the last quercetin^ alone. Perkin^ shows definitely that 
early workers who ascribed quercetin (either free or glucosidal) to the 
leaves of R. Coriaria and R. Cotinus were in error. The data given 
above provide our only reliable data in regard to the distribution of 
the flavones in Rhus. Perkin emphasizes the fact that in all species 
thus far investigated the wood flavone is different from the leaf flavone. 
Our paper provides further data for establishing a generalization with 
regard to this point, and also gives the first identifications of flavones 
from American sumachs. 
Acree and Syme^ have reported fisetin from the leaves of Rhus 
Toxicodendron L. (= Toxicodendron vulgare Mill.), in which they sup- 
pose it to occur both free and as one constituent of a glucoside to which 
they ascribe the poisonous properties of this plant. They give no 
analysis of the flavone which they isolated, but from their own state- 
ment that it yields protocatechuic acid and phloroglucinol on potash 
fusion, we infer that it was quercetin rather than fisetin. Fisetin 
would have given protocatechuic acid and resorcinol. In a recent 
refutation of a paper by McNair*^ in which the work of Acree and 
Syme is called into question, Acree^ explicitly verifies the earlier state- 
ment of Acree and Syme that a quantity (two grams) of the flavone 
which they obtained from the leaves of R. Toxicodendron and identified 
as fisetin was decomposed by potash fusion into phloroglucinol and 
protocatechuic acid. He states that the color reactions of the flavone 
were those of fisetin, but unless these substances are very carefully 
purified, there is much likelihood of error. Quercetin or even luteolin 
^ Perkin, A. G. Yellow colouring principles contained ir various tannin matters. 
Part VII. Arctostaphylos Uva-ursi, Haematoxylon Campeachianum, Rhus Metopium, 
Myrica Gale, Coriaria myrtifolia, and Rohinia pseudacacia. Journ. Chem. Soc. 
(London), Trans. 77: 423-432. 1900. 
Acree, S. F., and Syme, W. A. Some constituents of the poison-ivy plant. 
Amer. Chem. Journ. 36: 301-321. 1906. The same paper under a different title. 
Journ. Biol. Chem. 2: 547-573. 1906-7. 
6 McNair, J. B. The poisonous principle of poison oak. Journ. Amer. Chem. 
Soc. 38: 1417-1421. 1916. 
