Read it through once

Another interesting plant much cultivated in the Riviera is the Cassier (_Acacia farnesiana_). It is really a native of India, but was introduced from the West Indies to Europe in 1656. Cannes, Grasse, Antibes, and Nice are the places where it is most cultivated. Its flowers appear from July to November. An old tree may yield as much as twelve to twenty pounds of flowers, worth about five to six francs. But 116 pounds of flowers only yield about a pound of essence, so that it is not surprising that this last is worth £60 the pound.