88 MISSOURI BOTANICAL GARDEN BULLETIN 
who can count up to five should always be able to avoid the 
dangerous plant (plate 24). It is true that the shape of the 
leaflets of the two plants is practically the same, but the 
difference in number furnishes an absolute guide. When the 
plants are in fruit an additional distinction is to be found, 
the Virginia creeper producing drooping bunches of purplish 
berries, while poison ivy bears erect clusters of somewhat 
smaller white berries. 
Another plant to be avoided in the fall, especially when 
collecting colored leaves in swampy places is the poison sumac 
(Rhus vernix). While this never grows as a vine, as does 
Rhus Toxicodendron, it may appear as a shrub only a few feet, 
in height or a tree from fifteen to twenty feet high. The 
number of leaflets is of no assistance in separating the poison 
sumac from various other non-poisonous sumacs which have 
leaves turning red. Aside from the fact that any sumac 
growing in wet bogs is almost certain to be the poisonous 
one, the best distinguishing characteristic is its slender bunch 
of pale berries in contrast to the erect clusters of red or brown 
fruits of the harmless sumacs. Poison sumac to most people 
at least is more virulent in its action than is poison ivy. 
On the Pacific eoast is found the so-called ‘‘poison oak,’’ 
which has sometimes been separated from the poison ivy of 
this region because of the shape of its leaves. Botanically, it 
is known as Rhus diversiloba, but it is a question whether it 
is entitled to a special name since it agrees very closely with 
our R. Toxicodendron. 
There are, however, other species of the genus Rhus which 
are capable of producing symptoms similar to that of poison 
ivy, notably the one which is used in the manufacture of 
Chinese or Japanese lacquers. These lacquers are made from 
the sticky, brown sap which exudes from Rhus verniciflua 
when wounded. The recent epidemic of dermatitis among 
the devotees of Mah Jong was due to this poison. The var- 
nish used on the tiles, although perfectly dry, is still capable, 
when handled, of giving off the irritating principle. 
The Chinese, when working with this lacquer, have a 
typically quaint method of prophylaxis. They rub the hands 
and face with rape-seed oil, in which a ham has been boiled, 
