208 HYDROCHARIDACE^. 



In some instances, from an inexperience of the injury done by this water- 

 weed, it has been intentionally introduced. This was the case in regard to 

 the river Cam. In 1847 a specimen was brought from the Foxton lock, and 

 placed in a tub in the botanical garden of Cambridge ; and in the succeeding 

 year a small portion of the weed was placed there in the conduit stream, the 

 exact spot being, as usual in such cases, indicated by a small stick. In the 

 next year the plant had not only quite covered the stick from view, but had 

 extended itself and spread all over the ditch. Thence it made its way into 

 the Vicar's brook; thence into the Cam. "Thus," says Mr. Marshall, "we 

 see proved to demonstration, that the short space of four years has been 

 sufficient for one small piece of Anacharis to multiply so as to impede both 

 navigation and drainage." A story is current that a lecturer on botany, in 

 Scotland, who was remarking on the peculiarities of this plant, directed his 

 hearers to look for specimens in a neighbouring canal, in which he assured 

 them he had, some time since, planted the weed, and where indeed they 

 found it. In the course of some time the evil thus inadvertently introduced 

 had so injured some water-works by its masses, that the owner of the water 

 threatened the lecturer with legal proceedings for having brought it there. 



A remarkable circumstance respecting this weed has led to the inference 

 that all the plants in this country have proceeded from a single piece. The 

 flowers bearing pistils and stamens occur on different individual plants, and 

 in every specimen of the Anacharis seen in this kingdom until many years 

 after, the pistil-bearing flower only was found— and thus it was not, as in the 

 rivers of America, propagated by seed. In that country an identical or 

 closely allied species exists in profusion, but in the more rapid waters it is 

 not injurious, as in the still or slow-moving streams of this kingdom. 



Although the Anacharis was at one time so abundant in Dunse loch that 

 a boat could with difficulty be pulled among it, yet it has now quite dis- 

 appeared from that place. The same thing has since happened in many 

 places where it abounded soon after its introduction. A correspondent in 

 tbe Berwick Warder attributes its removal to the swans, though these birds, 

 he says, were accused of having originally brought it there. He remarks 

 that the swans lived entirely on this plant, throve well, rearing a numerous 

 family on the quiet waters, till the year 1851, at which period the plant dis- 

 appeared ; the birds then seemed to pine, and finally all died, save the 

 original pair. These swans, no longer able to find this favourite food in the 

 loch, followed the small burns down to the AVhiteadder in search of it, and 

 seemed to be its most relentless persecutors. Swans, as Avell as ducks, geese, 

 and other aquatic fowls, Avill probably aid in its destruction, as they destroy 

 the weeds which they feed upon ; and an observer of their habits remarks, 

 that " they have been known, when water-weeds were scarce, to eat through 

 large masses of white lilies, leaving nothing but the stem. Everything less 

 strong in its growth than the yellow water-flag seems to be destroyed by the 

 cropping of these birds." 



The Anacharis is called by the fishermen the Water Thyme, from a very 

 slight resemblance to the foliage of Thyme, in the form of the young branches 

 clad with leaves. 



