A frenulum (or frenum) is a small fold of tissue that prevents an organ in the body from moving too far.
Cover crops usually are grown to prevent soil loss from wind and water erosion. Use fast-growing cover crops, such as winter wheat or annual rye, on fall-spaded gardens. A second, and probably more important reason home gardeners should use cover crops is to improve soil structure and increase organic matter.
House Plants. Purple shamrock (Oxalis triangularis) is a houseplant in cold winter areas. In USDA zones 6 through 10, it can grow outdoors in borders or edgings. Purple-leaved plants do best in light shade and moist soil. White or pinkish flowers contrast well with the dark leaves. Volcanic sorrel (Oxalis vulcanicola), hardy in zones 9 through 11, has several colorful-leaved cultivars.