Liliales (older name: Lilia) is an order of monocotyledonous flowering plants in the Angiosperm Phylogeny Group and Angiosperm Phylogeny Web system, within the lilioid monocots. This order of necessity includes the family Liliaceae. The APG III system (2009) places this order in the monocot clade. In APG III, the family Luzuriagaceae is combined with the family Alstroemeriaceae and the family Petermanniaceae is recognized. Both the Lililiales order and the Liliaceae family have had a widely disputed history, with the circumscription varying greatly from one taxonomist to another. Previous members of this order, which at one stage included most monocots with conspicuous tepals and lacking starch in the endosperm are now distributed over three orders, Liliales, Dioscoreales and Asparagales, using predominantly molecular phylogenetics. The newly delimited Liliales is monophyletic, with ten families. Well known plants from the order include Lilium (lily), tulip, the North American wildflower Trillium, and greenbrier.
Thus circumscribed, this order consists mostly of herbaceous plants, but lianas and shrubs also occur. They are mostly perennial plants, with food storage organs such as corms or rhizomes. The family Corsiaceae is notable for being heterotrophic.
The order has worldwide distribution. The larger families (with more than 100 species) are roughly confined to the Northern Hemisphere, or are distributed worldwide, centering on the north. On the other hand, the smaller families (with up to 10 species) are confined to the Southern Hemisphere, or sometimes just to Australia or South America. The total number of species in the order is now about 1768.
As with any herbaceous group, the fossil record of the Liliales is rather scarce. There are several species from the Eocene, such as Petermanniopsis anglesaensis or Smilax, but their identification is not definite. Another known fossil is Ripogonum scandens from the Miocene. Due to the scarcity of data, it seems impossible to determine precisely the age and the initial distribution of the order. It is assumed that the Liliales originate from the Lower Cretaceous, over 100 million years ago. Fossil aquatic plants from the Cretaceous of northeastern Brazil and a new terrestrial species placed in the new genus Cratosmilax suggest that the first species have appeared around 120 million years ago when the continents formed Pangea, before dispersing as Asia, Africa and America. The initial diversification to the current families took place between 82 and 48 million years ago. The order consists of 10 families, 67 genera and about 1,768 species.