As with many other tropical fruits, the countries where it is most carefully produced and where the trade is most important are just on the borders of the tropics. There Europeans can keep enough vigour and vitality to supervise and watch over the labour of natives. It is in the Canary Islands, Queensland,[111] and Jamaica that the cultivation is most carefully looked after. The yield may be from five hundred to a thousand bunches per acre, and the value of the trade is enormous. A plantation is not very beautiful, because the huge leaves break up into irregular, ragged pieces which look untidy. The flowers are visited by the beautiful little honey-sucking sunbirds and humming-birds. Monkeys also are very fond of the fruit. [111] Queensland in 1900 had 6215 acres, and produced 2,321,108 bunches of bananas. In the tropics it grows everywhere, and with extremely little trouble. It is a doubtful blessing to the negroes, for they get their food so easily that they tend to become incorrigibly lazy. Jam, champagne, brandy, and meal can be made from the banana. When this meal can be prepared satisfactorily, it may partly replace wheat in temperate countries. Besides this, the leaves are used for thatching, and the stalks which make the stem contain a valuable fibre which is used for string and rope. In Egypt and all along the great deserts of Sahara and Asia the graceful stately Date palm gives the favourite food of the people (see Chap. X.). The Arabs grind up the stones to make food for camels, and sometimes ferment the sap to make toddy. The trees are either male or female. The Arabs knew that it was necessary to pollinate the female flowers with male pollen long before the meaning of the process was realized in Europe. The Fig, a native of the Persian Gulf, is cultivated all along the Mediterranean and in India, Australia, and California. It is sometimes fifteen to thirty feet high, and reaches a very great age. There is one at Finisterre said to be several centuries old. It yields fruit worth about £14 an acre. The most interesting point about the Fig is the way in which the Fig-wasp carries the pollen (see Chap. V.). Olives are also one of the most important and characteristic Mediterranean trees. The crop in both Spain and Italy is worth about £8,000,000 to £9,000,000 annually. In California it is also successfully cultivated, and pays very well. The peculiar taste of the dessert olive is obtained by soaking it in lime or potash, and then in vinegar or salt.