Carrots contain high quantities of vitamin A. Carrot cultivars can be grouped into two broad classes, eastern carrots (purple, yellow, often with branched roots) and western carrots (with an abundance of carotene). Carrots benefit from companion plants. Onions, leeks and chives for instance help repel the carrot root fly. Carrots can be stored for many months in a refrigerator, or in moist, cool places in winter. For long-term storage, carrots can be stashed in a bucket between layers of sand. A storage temperature of 0 to 5 °C is ideal.