North America is home to approximately four dozen bulbous genera. Among these are some very popular rock garden plants, such as Calochortus, Erythronium, and Fritillaria, which have never had anything substantial written about them in book form. Others, including Calydorea, Hypoxis, and Muilla, are not as well known outside specialist collections. The characteristics that make bulbs so desirable in gardens include their great diversity of flowering time, color, size, and form; their ability to adapt to a wide range of environments; and their capacity to multiply...