Lemon is a small, spreading, evergreen tree. A lemon tree can reach a height of 10 meters (30 feet), although the average tree is generally smaller. It grows well in temperate and tropical settings. Stems and branches often have with sharp, fleshy thorns. The leaves are green, shiny and elliptical. Flowers are white and have fragrant. The fruit grows underneath the flowers. Lemon trees produce fruit all year round. One tree can yield between 500 and 600 pounds of lemons in a year. In fact, the fruit is a modified berry with tough, leathery rind. Interior flesh is composed of segments, called carpels, made up of numerous juice-filled vesicles that are actually specialized hair cells. Some fruits are seedless, most have a few seeds. Lemon fruit is very sour, has a refreshing smell and tart flavor. The origin of the lemon is unknown, though lemons are thought to have first grown in northeast India, northern Burma or China. Ancient Egyptians believed that eating lemons and drinking lemon juice was an effective protection against a variety of poisons. The first large cultivation of lemons in Europe began in Italy in the middle of the 15th century. Fashionable ladies used lemon juice as a way to redden their lips during the European Renaissance. In 1747, James Lind's added lemon juice to the diet of seamen suffering from scurvy, though vitamin C was not yet known. To this day, the British Navy requires ships to carry enough lemons so that every sailor could have one ounce of juice a day.