| Taxonomy of Liliaceae Temporal range: Late Cretaceous - Recent
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|---|---|
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| Lilium candidum | |
Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Liliales |
| Family: | Liliaceae Juss.[1] |
| Type genus | |
| Lilium | |
| Type species | |
| Lilium candidum | |
| Subfamilies and tribes[2] | |
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| Diversity | |
| About 600 species | |
The taxonomy of the plant family Liliaceae has had a complex history since its first description in the mid-eighteenth century. Originally, the Liliaceae were defined as having a "calix" (perianth) of six equal-coloured parts, six stamens, a single style, and a superior, three-chambered (trilocular) ovary turning into a capsule fruit at maturity. The taxonomic circumscription of the family Liliaceae progressively expanded until it became the largest plant family and also extremely diverse, being somewhat arbitrarily defined as all species of plants with six tepals and a superior ovary. It eventually came to encompass about 300 genera and 4,500 species, and was thus a "catch-all" and hence paraphyletic. Only since the more modern taxonomic systems developed by the Angiosperm Phylogeny Group (APG) and based on phylogenetic principles, has it been possible to identify the many separate taxonomic groupings within the original family and redistribute them, leaving a relatively small core as the modern family Liliaceae, with fifteen genera and 600 species.
The Liliaceae emerged from the Liliales order, separating from its sister clade around 52 million years ago (mya), and diversifying around 34 mya. Of the major clades, the Lilieae arose in Eurasia while the Medeoleae arose in North America but was subsequently dispersed, as may have the Streptopoideae and Calochortoideae. Liliaceae fossils have been dated to the Paleogene and Cretaceous eras in the Antarctic.
The Liliaceae probably arose as shade plants, with subsequent evolution to open areas including deciduous forest in the more open autumnal period. This was accompanied by a shift from rhizomes to bulbs, to more showy flowers, the production of capsular fruit and narrower parallel-veined leaves.
While the suprageneric (above genus level) structure of the family has varied greatly with its ever-changing circumscription, as currently constituted the family consists of three subfamilies: Lilioideae, Calochortoideae and Streptopoideae. Lilioideae is further divided into two tribes, Medeoleae and Lilieae. The three subfamilies contain fifteen genera and approximately 600 species in all.