THE PERTINACITY AND PREDOMINANCE OF WEEDS.! 
A WEED is defined by the dictionaries to be “ Any useless 
or troublesome plant.” ‘ Every plant which grows in a field 
other than that of which the seed has been (intentionally) 
sown by the husbandman is a weed,” says the “ Penny Cyclo- 
pedia,” as cited in Worcester’s Dictionary. The “Treasury of 
Botany” defines it as “ Any plant which obtrusively occupies 
cultivated or dressed ground, to the exclusion or injury of 
some particular crop intended to be grown. Thus, even the 
most useful plants may become weeds if they appear out of 
their proper place. The term is sometimes applied to any in- 
significant-looking or unprofitable plants which grow profusely 
in a state of nature; also to any noxious or useless plant.” 
We may for present purposes consider weeds to be plants 
which tend to take prevalent possession of soil used for man’s 
purposes, irrespective of his will; and, in accordance with 
usage, we may restrict the term to herbs. This excludes pre- 
dominant indigenous plants occupying ground in a state of 
nature. Such become weeds when they conspicuously intrude 
into cultivated fields, meadows, pastures, or the ground around 
dwellings. Many are unattractive, but not a few are orna- 
mental; many are injurioys, but some are truly useful. 
White Clover is an instance of the latter. Bur Clover (Je- 
dicago denticulata) is in California very valuable as food for 
cattle and sheep, and very injurious by the damage which the 
burs cause to wool. In the United States, and perhaps in 
most parts of the world, a large majority of the weeds are 
introduced plants, brought into the country directly or indi- 
rectly by man. Some such as Dandelion, Yarrow, and prob- 
ably the common Plantain and the common Purslane, are 
importations as weeds, although the species naturally occupy 
some part of the country. 
1 American Journal of Science and Arts, 3 ser., xviii. 161. (1879.) 
