BOTANY. 335 



it appeared in Derbyshire and Staffordshire, " forming very large sub- 

 merged masses of a striking appearance," in the Trent and adjoining 

 canals. In 1850, it was found near Rugby, in Warwickshire ; and in 

 1851, it was discovered in the rivers Ouse and Cam, near Cambridge. 

 The botanical interest which was at first excited by the discovery 

 of large quantities of this new plant in various districts, at nearly the 

 same time, soon gave place to a feeling of serious alarm prompted by 

 the injurious effects of its unparalleled increase. A year after it was 

 first noticed in the Cam, the stream near the colleges was so blocked 

 that extra horses were required to draw barges through the vegetable 

 mass. A year after its appearance at Ely, the railway dock became 

 so choked with the weed that boats could not enter until several tons 

 of it had been removed. In many places fishermen were obliged to 

 discontinue setting long lines, or using nets, because the weed either 

 carried them away or stripped them of the fish. It is evident that this 

 plant, styled by Mr. Babington, of Cambridge, the anarJiaris alsinastrum, 

 cannot a great while have been a native of Great Britain. If so, its 

 remarkable prolific powers would long since have brought it into 

 notice. And it is a noteworthy fact that the anacharis is dioecious 

 that is, the male and female flowers grow on separate individuals 

 and all the plants known to exist in England are females. This fact 

 affords an almost positive proof that only one stem or seed of a female 

 plant was the progenitor of all the anacharis in Great Britain ; and 

 this seed was possibly introduced from Canada in the crevice of some 

 one of the many logs which are annually conveyed across the ocean to 

 England, and of which so many have been used in the great railroad 

 works at or about Rugby. It is thought that in the clear, swift-flowing 

 rivers of America, the weed would not form the immense masses which 

 characterise its growth in the sluggish and as they contain a greater 

 amount of inorganic animal and vegetable matter more nourishing 

 waters of the English rivers and canals. But our readers will inquire 

 how as only the female anacharis has been discovered in England, 

 and it is therefore unable to propagate seed in that country how it 

 contrives to extend itself so rapidly and widely, and wherein are its 

 prolific powers vested. These questions are easily answered ; its 

 leaves, which grow in threes, around a slender stem, are studded with 

 minute teeth, which cause them to cling to every object with which 

 they come in contact, and the stems are so very brittle that whenever 

 the plant is disturbed pieces are broken off ; and as every fragment of 

 the stem is capable of becoming an independent plant, producing roots 

 and leaves, and extending itself indefinitely in every direction, it is 

 evident that the anacharis must be in an almost continual state of 

 reproduction. All the localities in which this singular plant seemed 

 to appear almost simultaneously, are reducible to two Dunse Lake 

 in Berwickshire, and the Foxton Locks in Liecestershire. It proba- 

 bly originated in the Foxton Locks, and was afterwards introduced 

 into the former place. The Foxton Locks are in direct communica- 

 tion with nearly all the English localities of the plant, and a single 

 sprig of the anacharis would in a very short tune inoculate any con- 



