The plants are distinctive vegetatively, with a rootstock consisting of a slender rhizome or group of rhizomes (the "crown"). Storage roots consist of sausage-like water storing structures "suspended" from the rhizome by major roots. In this way the root system resembles that of dahlias. Above-ground shoots may be very short in some alpine Andean species (a few inches tall) or up to about 5 feet (1.5 m) tall in other species. Each year (more often in some hybrids) up to 80 new shoots are produced from the rootstock and each terminates in an umbel of a few up to 10 or so flowers.
Perhaps the most fascinating- and telltale- morphological trait of Alstroemeria and its relatives is the fact that the leaves are resupinate, that is, they twist from the base so that what appears to be the upper leaf surface is in fact the lower leaf surface. This very unusual botanical feature is easily observed in the leaves on cut flowers from the florist.
The flowers of Alstroemeria are generally showy. All six tepals (tepal denotes either petal or sepal when both are similar, as in lilies, amaryllis, etc.) are roughly similar. In some species two tepals are enlarged and vividly colored and act as "flags" for pollination. The ovary is inferior and the seeds are hard and rounded.
See also Bomarea, the other major genus in the Alstroemeriaceae. They are essentially twining Alstroemerias (though some species are not vining), with most species occurring in the Andes.
Alstroemeria is named after the Swedish botanist Baron Klas von Alstroemer.