It may not be the mother of all lemons, but Lisbon lemon, Citrus limon ‘Lisbon’, is the original cultivar from which ‘Eureka’ lemon was derived; and ‘Variegated Pink’ lemon was later derived from ‘Eureka’ lemon. ‘Variegated Pink’ is still uncommon, and the pink juice is unusual, but because its variegated foliage is less efficient than greener foliage, it is more manageable in small spaces.
The only distinguishable difference between ‘Lisbon’ and ‘Eureka’ is the scheduling of the fruit. Both are the biggest of the dwarf citrus, and can get as tall as second story eaves. Both have nicely aromatic glossy green foliage. Both are somewhat thorny, and get big thorns on vigorous growth. Yet ‘Lisbon’ is now rare, while ‘Eureka’ is second in popularity only to the unrelated ‘Meyer’ lemon.
That is because, after primary winter production, ‘Eureka’ continues to produce sporadically throughout the year, which is what most of us want in our home garden. ‘Lisbon’ may seem to be more productive, but only because it produces all of its fruit within a limited season that is finishing up about now. The fruit that ripens now may linger for months, but no new fruit ripens until next season.