Wallflower and Cabbage 89 
rapidly have they found out that no allied species 
had grown there before to rob the soil of the 
particular ingredients they chiefly required. About 
thirty years ago, the Water-cress (Nasturtiwm 
officinale) having got itself “transported” to New 
Zealand, had become the cause of much expensive 
mischief to the rivers and waterways, the stem 
growing to a length of twelve feet, and as_ thick 
as a man’s finger, forming network across rivers that 
put a stop to navigation, except where hundreds of 
pounds per annum were spent in keeping down the 
growth. The petals of this plant are white, and 
larger than the sepals, but, still very small,—less than 
a fourth of an inch across. It is chiefly fertilised 
by beetles. Its numbers are kept down in this 
country by the demands upon the plant for table 
use as an anti-scorbutie. 
It is worthy of note that most or all the numerous 
members of the family share this anti-scorbutic 
property, which has caused many to be selected for 
cultivation—such as Cabbage, Turnip, Radish, Mustard, 
ete. They are rich in nitrogen and sulphur, and it 
is the giving off of these substances that produces 
the unpleasant odours from cabbage-fields and the 
water that “greens” have been boiled in. From the 
same principles they elaborate the pungent, hot, or 
acrid flavours which cause many of them to be 
esteemed by man, though this is a protection set 
up by the plant to ward off the attacks of herbivorous 
animals. These plants in the wild condition are but 
little affected by insects, yet in a cultivated state 
they are much esteemed as caterpillar food, as a 
glance at the riddled leaves of our cabbages will 
