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We have two species of Rhus which are poisonous to the touch. One of 
these is called poison-ivy, and may be met with in almost any woods, run- 
ning over rocks or ascending trees. The other species is a shrub which 
grows in swamps. Some persons are much more susceptible than others 
to the poisonous influence of these plants. Indeed, many people can 
handle them with impunity, while others are poisoned by a touch, and 
some think that the mere neighborhood of the plant communicates the 
poison. The poison-ivy vine is often confounded with the Virginia 
creeper, or woodbine, (Ampelopsis quinguefolia,) which is perfeetly harm- 
less. They may be readily distinguished by observing that the leaves 
of the ivy are in threes, while those of the creeper or woodbine are in 
fives. 
A few of our native plants enjoy the reputation of being poisonous, 
rather from their relationship to other poisonous plants than from aetual 
poisonous properties. This is the case with some species of Solanum 
and Physalis, which belong to the natural order Solanacew, where also 
belong tobacco, henbane, nightshade, and other poisonous plants. So- 
lanum nigrum, sometimes called ground-cherry, is very common in waste 
places and in cultivated fields, and is thought by some to be poisonous, 
but I have often seen its black berries eaten with relish and without 
harm, and even made into pies, for which they are not sufficiently tart 
to be agreeable. 
Mr. Bailey, in an interesting article on this subject, in the American 
Naturalist, relates seeing a boy eating the large green potato-berries 
without any resulting trouble. 
We have several species of Physalis, or ground-cherry, whose berries, 
when mature, are pleasant-tasted and harmless. The more general dif- 
fusion of botanical knowledge would undoubtedly be the means of avoid- 
ing much suffering and many accidents which now occur from ignorance 
of the nature of the plants. 
HARDHACK AND POTENTILLA FRUTICOSA.—Since the publieation in 
the December report of Mr. T. 8. Gold’s remarks on Potentilla fruticosa, 
several correspondents have expressed their apprehension that he may 
have meant the Spirea tomentosa, which is well known throughout the east- 
ern States as “hardhack.” This however was not the case, as Mr. Gold 
sent a specimen of the plant he alluded to, and it was the true Poten- 
tilla fruticosa, which seems also to have received the name of hardhack 
in that part of the country. This illustrates the great difficulty which 
often arises in identifying any plant by the common or local name. 
Botanical names, although sometimes hard to learn, have the virtue of 
being precise, and of always and everywhere meaning the same plant. 
In confirmation of Mr. Gold’s statement that the Potentilla fruticosa 
was one of the most formidable weeds of that section, we publish the 
following from Mr. D. F. Smith, of Goshen, Connecticut : 
I have wondered whether the “hardhack” referred to by Mr. Gold was not a differ- 
ent shrub from that referred to by Mr. Beardslee of Ohio and others. I would say with 
all possible emphasis that what we in these western counties of Connecticut and Massa- 
chusetts know as “hardhack,” and which Mr. Gold identifies as Potentilla frwticosa, 
is a very great nuisance, having cansed damage in this town, and in other single town- 
ships, that would require thousands of dollars to represent. Hundreds of acres in this 
town, that twenty-five years ago were good pasture-land, have been rendered worth- 
less by the rapid spread and dense growth of what we call ‘“ hardback.” 
There need be no difficulty in discriminating between these two shrubs; the Potentilla 
fruticosa has pinnate leaves, and bright yellow flowers, while the Spirea tomentosa has 
single ovate or oblong leaves, and rose-colored or nearly white flowers. Spirea_tomen- 
tosa is more erect and less branching, with the small flowers densely crowded into a 
spike which terminates the stalk. 
FORESTS AND RAIN-FALL.—The ‘Bulletin of the Torrey Botanical 
Club” for February contains a letter from Mr. Fred. Hubbard, which 
