The ponerosa lemon is thought to be a lemon X citron hybrid. It is similar to a lemon but the fruit is much larger with a thick bumpy peel and no pointed tip. the ponderosa lemon averages 2-4 pounds, and has been nicknamed the 5 pound lemon. the ponderosa lemon tree averages 10 to 25 feet tall and the dwarf tree averages about 8 feet tall.