Oxalis is derived from a Greek word, meaning sour, and refers to the acid juice of the plant. In the cool, shady recesses of our mountainous regions this dainty plant is fairly rampant. Our Northern forests are literally carpeted with its fretwork of leaves, which are formed into green patches, or beds of every conceivable angle where they are crisscrossed by the runways of deer or moose and decaying, mossy trunks of fallen trees. In May and June these lovely, leafy groupings are starred with the strikingly large and beautiful flowers which are white, pink-tinted or veined. The Clover-like leaves fold downward at night, not unlike a clumsy umbrella. This species is native in Europe, Asia, and Northern Africa. It was familiar to the old Italian masters, and was introduced into some of the early Christian paintings by Angelico and Botticelli. Oxalic acid is produced from its leaves, and is commonly known as Salt of Lemons, which is extensively used by painstaking housewives and laundresses for removing rust stains from linen. The leaves are borne on slender stems, which, rising from a scaly, creeping rootstock, grow to be from two to six inches in height. The single flower is broadly bell-shaped, and has five rounding, notched petals, with five long and five short stamens. This plant also bears the curious, bud-like flowers that fertilize themselves without opening, and which are called cleistogamic, and are borne near the root on short, curved stems. The name Alleluia came to be a favoured one in England, because the flowering season occurred during Easter week. Some believe this to be the true Shamrock of the ancient Irish, dating back to the time of St. Patrick. The White Wood Sorrel ranges from Nova Scotia to Manitoba, and south to New England and New York, and in the mountains to North Carolina.