174 THE GEOGRAPHY OF PLANTS. 



Greeks extracted their tar in precisely the 

 same way as do the Bothnians at this day. 

 150,888 barrels of tar were imported in 1848, 

 each barrel containing thirty-one and a half 

 gallons. The climate and productions of 

 Norway and Sweden cannot be taken, how- 

 ever, as a fair specimen of the vegetation of 

 this zone ; as, from their peninsular character, 

 they enjoy a much warmer temperature than 

 almost any other country within its limit. 

 Even here, however, the apple ceases at 63^, 

 the cherry at 63, and the pear at 62. The 

 vegetation of Iceland in the meadows and 

 pastures is much the same as our own ; there 

 is, however, a total want of trees, for the birch 

 and alder, though abundant, attain but a small 

 height. Corn is cultivated to a very trifling 

 extent, often not at all for a long series of 

 years, for, towards the end of summer, the 

 weather is so changeable that the grain seldom 

 ripens. The sea pea (which we have already 

 noticed) is used as an article of food, and they 

 are said to be very well flavoured. The prin- 

 cipal vegetables, such as cauliflower, potatoe, 

 turnip, etc., succeed. Many of the sea- weeds 

 are collected, and used as food. The Iceland 

 moss (Cetraria Islandicd) is also gathered for 

 food ; it grows in great quantities, and is 

 collected from the same grounds every three 

 years. The bitterness of the plant is extracted 

 by soaking it in water, and it is then eaten, gene- 

 rally boiled with milk ; a kind of bread is also 

 made of it. The time of gathering the Iceland 



