THE PLANTS OF THE SEA. 35 
Those plants of the ocean which vegetate upon the surface of 
the water without adhering to any fixed body, frequently interlace 
and form islands of vegetable matter, which the currents transport 
and at length strand on some unknown shores, or the storms 
scatter. 
To the south-east of Newfoundland, not far from the Azores, 
THE GULF WEED. 
Sargassum bacctferuni.) 
- there is an immense bank of sea-plants, composed of floating 
wrack, one of the most common of the marine fuci. This bank is 
named the Sargasso Sea, for the weed belongs to the genus Sar- 
gassum. This gigantic mass astonished Columbus, who thought it 
marked the limits of navigation. It was called by Oviedo, the 
Prairie of Weeds. These beds of floating plants sometimes gather 
round ships in an alarming manner. The Gulf weed occupies a 
triangular area equal in extent to the valley of the Mississippi. 
Many of the alge float upon the surface of the sea, sometimes 
joined together, sometimes in a small number, at other times 
forming broad bands or oases in the desert of waters. Amongst 
these plants we ought to mention the sea /ettuce (ulva), with its 
large and thin leaves, which have a greenish tint sometimes 
shading off into dark violet. One species resembles a_ long 
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