Nucellar selection of Lisbon lemon. It was derived in 1917 by H. B. Frost of the Citrus Research Station, Riverside, and was released about 1950. Fruit medium in size, elliptical to oblong; base tapering to inconspicuous neck; apex tapering likewise into a usually large, prominent nipple surrounded by an irregular areolar furrow, commonly deeper on one side. Seed content variable, but usually few to none. Color yellow at maturity. Rind medium-thick; surface finely pitted, faintly rugose, inconspicuously ribbed if at all; tightly adherent. Segments about 10; core small and solid. Flesh color pale greenish-yellow; fine-grained, tender, juicy; flavor very acid. Crop comes mainly in winter and early spring. Tree vigorous, upright-spreading, large, thorny, densely foliated, and productive. Tree most vigorous of varieties grown in California and most resistant to adverse conditions such as frost, heat, wind, and neglect. The Lisbon fruit is generally smoother and less ribbed than Eureka, the nipple and areolar furrow more prominent, and the taper at the ends more gradual. The characters are so variable and overlapping, however, as to make identification from small samples uncertain, if not impossible. The tree is quite different from the Eureka, however, and easily distinguishable.