The loss of agrobiodiversity is a topic of global impact. On a local scale, Lombardy, in the Alpine macro-Region, has lost more than 78% of its plant agrobiodiversity. Only four maize (Zea mays L. subsp. mays) landraces of Lombardy are registered in the European Register of Conservation Varieties. However, there are other maize landraces in Lombardy such as “Mais delle Fiorine”, which was characterized from an agronomic, morphometric, nutritional and genetic point of view in this research and then compared with the four other landraces already registered (“Spinato di Gandino”, “Rostrato Rosso di Rovetta”, “Scagliolo di Carenno” and “Nero Spinoso”). “Mais delle Fiorine” resulted richer in starch (81% ± 1.6) and zinc (35.8 ± 9.1 mg Kg−1) and lower in phosphorus (3256.7 ± 204.2 mg Kg−1). The kernels in the five landraces also differ in the mean shape that is obovate without beak. A genetic distinction between “Mais delle Fiorine” and the other varieties was observed, and in particular compared to “Nero Spinoso”, while “Scagliolo di Carenno” and “Rostrato Rosso di Rovetta” showed great similarities. As regards agronomical trials, “Mais delle Fiorine” can grow from the Po Valley (90 m a.s.l.) to the mountain environments of the Seriana Valley (also over 900 m a.s.l.) without significant differences in grain yield. In addition, this landrace would seem able to tolerate environments where there is a greater probability of water stress.