CORRESPONDENCE. 245 
A collection of the various species of Salix and Rubus would also be 
most welcome." 
CORRESPONDENCE. 
Weeds and their Characteristics. 
I am much pleased with the paper on the derivation of the word weed 
in your last number. It may be said in nature that all plants are weeds, 
and that there is a continual struggle going on amongst them individually for 
an increase of territory ; and, although some may be overcome, yet, if left alone 
to nature's doings only, it is probable that, in the course of ages, the loss of 
species on the earth would be but small. According to my ideas, a plant 
ceases to be a weed when man has found that it is useful to him, takes it 
under his fostering care, and wages war over great areas for its supremacy 
over all its former weed-associates. It is therefore more by man's interven- 
tion than nature's that the great destruction of species on the earth takes place. 
In olden times this destruction was limited to the first civilized parts of the 
earth (Europe and Asia) ; but, since the discovery of the mariner's compass, 
the destroying angel has bom carried into distant lands, the most powerful 
and potent agent being the weed called Wheat. For the sake of its cultiva- 
tion fires have destroyed the forests of North America; the Silver-trees 
and beautiful Heaths, and all their associates of South Africa, have disap- 
peared j extensive tracts of natural vegetation of Australia and other countries 
have succumbed to its influence ; within these twenty years the beautiful dis- 
trict of New South Wales called Illawarra, where groves of Tree Ferns, 
p alms, and other tropical trees grew, covered with Orchidea and epiphytal 
Plants, with all the luxuriance of a Brazilian forest, have fallen before 
Ae white man's axe, and are now cultivated cornfields. The thickets of Sea- 
forthia, once towering 100 feet high, are no more to be seen ; solitary indivi- 
duals, with Fan Palms and Tree Ferns, may yet be found in ravines and 
«t-of-the-way places that man has not yet been able to make useful to his 
wants. The extinction of the Flora of this once-remarkable district is there- 
fore only a matter of time. It is also by the agency of the white man that the 
na tive pl ;m t s of New Zetland are being supplanted by the more powerful 
Phnts of the north, such as the White Clover, Water-cress, Polygonum avicu- 
hre, and such like other plants ; as also the grassy Pampas of South America 
are hy the European Thistle. 
With regard to naturalized weeds or plants in this country, I have but little 
| 08a y. It is true but few American speci have become wild. One, however, 
J a s become conspicuous (Anacharis Ahinastrum), which at one time it was 
fc»red w ul d choke up canals and rivers , but, as it carries its own destruction 
Wl thin itself, it is not now dreaded. It might have been expected that the 
