222 Annual Report for 1907 of the Consulting Botanist. 
The number of inquiries received in regard to this diagram 
manifests that considerable interest has been awakened in 
regard to the phenomena dealt with. It is not desirable to 
reproduce the diagram, or to publish any results until the trials 
are completed. 
Weeds. 
Some of the plants reported upon were poisonous, like 
Meadow Saffron, from damp meadows, and Euphorbia amyg- 
daloides Linn.), a spurge found in woods, which was growing 
in some land that had been deforested and had injured cattle 
feeding there. A branch of the American poison oak, Rhus 
radicans Linn, was sent from the shrubbery of a member of the 
Society, where it caused irritation and inflammation to some 
members of his family. The injury produced by this plant has 
been long known. It is caused by a poisonous substance 
called Toxicodendrol. The injury to the skin has been cured 
by the application of a saturated solution of arsenate of lead 
in alcohol. Energetic steps have been taken in America to 
prevent the cultivation of this shrub, and it would be well if 
its presence in our shrubberies in England were forbidden. 
Some weeds believed to be injurious to stock were found to 
be innocent. And others found in pastures or cultivated fields 
were named and advice given as to their eradication. 
In view of these applications it may be well to put on record 
some general conditions which should be kept before one in 
dealing with weeds. Any plant growing out of its proper place 
is a weed. A potato in a field of wheat, or oats in a turnip 
field are as. much weeds as thistles or nettles in a pasture. 
Plants which grow from seed, produce flower and fruit, 
and die within the year, like wheat, are called annuals. Plants, 
which live for two seasons, spend the first year in making and 
storing up food which is employed the second j’ear in produc- 
ing flowers and fruit. These, like the turnip, are called 
biennials. Plants which live for years and re 2 Jeatedly flower 
and fruit are called perennials. 
A preliminary step to dealing with growing weeds is to 
prevent their being brought on the land by rising only pure 
and clean seed. This can now easily be done. Many seeds 
found in the hay or straw with which stock is fed have such 
firm coverings that they pass through the alimentary canal 
without being injm-ed. The farm-yard manure thus becomes a 
medium of placing on the land the seeds of many undesirable 
weeds. 
The problem of getting rid of annual and biennial weeds is 
more easily solved than practically applied. They must be 
hoed out or pulled up before or when they are in flower. No 
effort short of this can get rid of them. They produce, as a 
