Key lime

Key lime, or Citrus aurantiifolia, is a small bushy citrus from Southeast Asia that Spanish ships carried to the Caribbean and the Florida Keys in the 1500s. Slender thorny branches hold fragrant white flowers and seedy fruit about 1.5 to 2 inches across, ripening greenish yellow to yellow with sharp juice. Give it full sun and well drained soil; it takes sand or rocky limestone but declines in flooded ground, and established trees want water only during long dry spells. Trees rarely top 12 feet, so a sheltered corner or a large container suits them. Hardy in USDA zones 9 to 11, Key lime is among the most cold sensitive citrus: foliage is damaged at 30 to 32 degrees F and wood dies below 29. Bloom peaks in spring, fruit ripens mainly in early summer in south Florida and late summer farther north, and the thorns argue for gloves.