“THE MIGRATION AND DISPERSAL OF WEEDS. 
The very troublesome weed of the Bright district (Victoria), St. 
John’s Wort (Hypericum perforatum), is also supposed to be a garden 
escape. It has a rather delicate yellow flower, the attractiveness of 
which caused its introduction into Victoria, where the conditions suit 
it so well that it grows to twice the size that it usually attains in England. 
It spreads with tremendous rapidity by means of long underground 
stems, and since it contains an oil which is slightly injurious to stock 
and very distasteful to them, and is very woody, it receives no check 
from grazing animals. ; 
The plant known in Victoria and New South Wales as Paterson’s 
Ourse, and in South Australia as Salvation Jane, and whose botanical 
name is Hchium plantagineum, is also a garden escape. It is 
characterized by long spikes of blue or faintly purple flowers; the flower 
stalks and leaves are covered with coarse hair, and are very rough, 
making it most unpalatable to stock. It has spread tremendously in 
parts of New South Wales, and causes a lot of trouble. 
The majority of weeds which have reached this country have been 
introduced accidentally, or by carelessness. 
Agricultural seed is very seldom absolutely free from impurities 
such as dust, small particles of seed pods, and more particularly weed 
seeds. It is impossible to grow most crops without a good many weeds 
growing at the same time, and it is equally difficult to collect the seed 
from the crop without collecting the weed seeds as. well. Certain weeds 
are habitually found in certain crops, and the seeds of these weeds 
naturally form common impurities in the crop seed. Lucerne crops 
are frequently infested with dodder (Cuscuta trifolit) (Fig. 10), and 
this means that lucerne seed is frequently adulterated with dodder seed. 
These seeds are particularly small and dust-like, and easily mistaken 
for particles of earth mixed with the kidney-shaped lucerne seed, and 
they can only be separated from it by careful sifting. Charlock or 
Wild Mustard (Brassica sinapistrum) is a weed which very frequently 
appears in a cornfield, usually having been introduced with impure 
seed. The same may be said of a great many of the Orucifere, which 
are troublesome weeds in cultivated ground. The Wild Radish or 
Jointed Charlock (Raphanus raphanistrum) has a fruit which breaks 
into segments, each segment containing seed, and looking very much 
like a grain of oats, which makes it particularly difficult to separate 
from that crop. Grass seeds for planting in pasture land are a particu- 
larly fertile source for the introduction of weeds. The seeds of all 
grasses are so small, and so much alike, that it is particularly difficult 
to separate them, and. all sorts of impurities in the way of Ragwort, 
Stinkwort, thistle seeds, &¢., can be mixed with them, and require 
careful investigation before they can be detected. It is probable that 
the weeds introduced into agricultural seeds are the main channel by 
which aliens are introduced into any district. . 
The practice of packing fragile goods in cheap straw or hay is one 
fraught with great danger to the farmer. The straw used is naturally 
some of the cheapest, and is mixed with numerous weeds. As a general 
rule, after it has been used for packing, it is thrown on to the rubbish 
heap, or used as bedding in the stable, and thrown on to the manure 
heap later. This provides the weed seeds with an excellent opportunity 
for germination, and some new weeds are soon prs osabout the 
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