SEAWEEDS 467 



solitary bladders in the centre of the fronds, above which the frond divides. 

 These bladders, as in other species, give the plant that buoyancy and support 

 needed under water. 



The Bladder Wrack (F. vesiculosus) is very similar, but has a broader 

 frond with a distinct midrib, and the bladders are in groups, frequently pairs, 

 on each side of the midrib. It is common wherever there are rocks, and is 

 much used by farmers for manure. 



The Saw-edged Wrack * (F. serratus) is named from the sharply toothed 

 edges of its broad fronds. It has no bladders. 



Another brown seaweed, which is almost as common, is the Sea-oak or POD- 

 WEED (Halidrys siliquosa), which is identified at once by its long, pod-like 

 air-chambers, each divided into several compartments. Other pods contain 

 the element from which the spores are produced, and these have perforated 

 surfaces. 



On the South Coast, specially, is a tufted weed which under water shines 

 with a beautiful iridescence, and is many branched, the branches being full 

 of little air-bladders. This is Cystoseira ericoides, known sometimes as the 

 Rainbow Bladder-weed. 



The Oarweed (Laminaria digitata) is a deep-water plant, reaching a height 

 of 10 or 12 feet. It is often flung ashore after storms, when it may be recog- 

 nized by its huge round stems, terminating in claw-like " roots," as most 

 people insist on calling the suckers. The leafy portion is broad and slit into 

 sections, so that the whole frond bears a rude resemblance to the fingers of 

 a hand. The stem is so tough that it can be used for making handles to knives 

 and other tools. When fresh, the tang of a knife can be thrust into it and 

 in a few months it is dry and fast, having contracted so as to fix the blade 

 immovably. 



Amongst the Laminance is to be found the Sea-rope (Chorda filum), attain- 

 ing a length of many feet. Its name is apt, for it consists of a long, tubular 

 frond, slimy to the touch, and covered, as your lens will show, with dense 

 fine hairs. 



Another familiar species is the Sugar Tangle (Laminaria saccharina). 

 This derives its name from the fact that when dry it is covered with a hoar- 

 frost-like powder, sweet to the taste, called mannite or manna. This species 

 is generally chosen by visitors to the sea to take back home as a weather gauge, 

 as it is a ready absorbent of moisture ; but the stem can be used as a handle 

 for forks and knives, like that of the Oarweed. The fronds are undivided 

 and glossy. 



L. bulbosa, Sea Furbelows, is recognized by the large hollow bulb from 

 which it springs, and which, being perforated, becomes a refuge for all sorts 

 of small creatures. It will be found on the shore after a storm, like so many 

 of the other seaweeds. 



* The word " wrack " is from the French varec = seaweed, and is still common in Jersey 

 patois as vraic. 



