Fl. forming a double triangle, 110 mm wide, facing up; perianth segments very broadly ovate, mucronate, shouldered at base, pure white, spreading, with margins slightly incurved, smooth and of heavy substance, with midrib showing, overlapping; the inner segments narrower; corona funnel-shaped, ribbed, salmon pink, mouth flared, lobed, frilled, with rim flanged and crenate. Sweetly scented

Named because it is usually in bloom on the 5th of May, which is also the date of the Mexican holiday when the Mexican army defeated the French at the Battle of Puebla.