There are many kinds of flowers which have been called "lilies", but many of these so-called lilies, such as the day-lily, water-lily, and arum-lily, actually belong to other groups of flowering plants. The image above should give you a good idea of the diversity in the Liliales. The pictures are (clockwise, starting from upper left): Bomarea, a tropical vine; Tulipa, the tulip; Trillium, the wake robin; Alstroemaria, a common bouquet flower; Calochortus, the Mariposa lily; and Colchicum, from which we get the drug colchicine.
At one time the Liliales was considered to be one of the largest groups of monocots. However, since the group has been redefined to exclude the Asparagales, Dioscoreales, and Iridales, a position which is supported by both molecular and morphological evidence, the Liliales is now a rather small group, with about 1200 species. As a whole, the order is distributed world-wide, though most families are concentrated on one or more continents. Some have a southern distribution, such as the South African Colchicaceae and South American Alstroemeriaceae, while the Liliaceae is primarily a northern group.
Plants in the Liliales grow from bulbs, such as the one shown below, or corms, both of which will store food over the winter or during the dry season. They have broader leaves than most monocots, many with the networking veins usually associated with dicots. Nearly all are herbs, but a few grow as vines, such as Smilax and Bomarea. Unlike other Liliales, these vines produce their flowers in spherical clusters called umbels, as in the picture of Bomarea at the top of this page.
Liliales : On the left, a bulb of Fritillaria; bulbs are underground fleshy storage leaves wrapped tightly around the stem, such as in onion and garlic. A bulb can fragment as a means of reproducing the plant. On the right, a fossil Smilax labidurommae leaf from the Oligocene age Florissant beds of Colorado; the fossil is housed in the UCMP collections.
Most other species do not produce dense clusters of flowers, and many produce a single flower per plant each year. Liliales have some of the showiest flowers in the plant world. Their large colorful tepals come in whites, yellows, browns, oranges and reds, blues and violets. The flowers are often variegated, having spots or streaks of other colors mixed in, and often have nectar-producing glands on the tepals or stamens, making them popular with bees and other such flower visitors.
The Asparagales and Dioscoreales have been lumped into the Liliaceae since approximately the beginning of this century. Recent work by morphologists and molecular biologists have reestablished the independence of these other groups. It has also been suggested that the Alstroemeriaceae may actually belong in the Orchidales, but this has not been well studied. Because the taxonomy of this group has been in such turmoil, it is difficult to interpret the fossil record. There is much fossil pollen which has been assigned to the Liliales under the name Liliacidites, but this may have to be reinterpreted in light of recent taxonomic changes. There are also heart-shaped fossil leaves from as early as the Cretaceous which may be from Smilax, but these have also been suggested as belonging to the Dioscoreales. In any case, it is quite likely that the group existed in some form by the Late Cretaceous, as it is believed to be one of the most "primitive" groups of monocots, that s, its appearance and ancestry indicate an early separation from other monocots.
The Liliales may be divided into the following families:
(number of species refers to living species only)
The University of Wisconsin has images of: Erythronium, Fritillaria, Lilium, Medeola, Smilax, Trillium, Tulipa, and Uvularia. For more pictures, try the Tulip Book of P. Cos, an on-line illustrated manuscript.
For more information about the Liliales, try the DELTA descriptions for the Alstroemariaceae, Calochortaceae, Colchicaceae, Liliaceae, Smilacaceae, Trilliaceae, and the Uvulariaceae.
Try Susan Farmer's webpages for a wealth of information about the family Trilliaceae.
Information about the use of colchicine for treating MS is available from the International MS Foundation.
R. M. T. Dahlgren and H. T. Clifford. 1982. The Monocotyledons: A comparative Study, 378 pp. Academic Press, London and New York.