Liliales

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 1300.

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.[2] The initial diversification to the current families took place between 82 and 48 million years ago.[3] The order consists of 10 families, 67 genera and about 1,500 species.

Description

The Liliales are characterised by (synapomorphies) the presence of nectaries at the base of the tepals or stamen filaments, together with extrorse (outward opening) anthers. This distinguishes them from the septal nectaries and introrse anthers that are the features of most other monocots.[3] They are mainly geophytes with elliptical leaves showing fine reticulate venation. The tepals are usually large and pointed. The outer integument epidermis of the seed coat is cellular, and the phytomelanin pigment is lacking. The inner integument is also cellular and these features are plesiomorphic.[4][5] The Liliales are predominantly perennial erect or twining herbaceous and climbing plants. They also include woody shrubs, which have fleshy stems and underground storage or perennating organs.

Taxonomy

History

Earlier names for this order include the Coronarieae of the Bentham & Hooker system. The Wettstein system, last revised in 1935, used names similar to those in the Engler system: the order was named Liliiflorae placed in the class Monocotyledones of the subdivision Angiospermae. In circumscription the order was fairly similar to that of Cronquist.

In the Engler system (1964 update) a similar order was named Liliiflorae, placed in the class Monocotyledoneae of the subdivision Angiospermae.

The Cronquist system (1981) placed the order in subclass Liliidae in the class Liliopsida [= monocotyledons] of division Magnoliophyta [= angiosperms]. It used a much wider circumscription (many of the plants here are assigned to Asparagales and Dioscoreales by APG II):

The Dahlgren system (1985) placed the order in superorder Lilianae in subclass Liliidae [= monocotyledons] of class Magnoliopsida [= angiosperms] and used this circumscription:

The Thorne system (1992) placed the order in superorder Lilianae in subclass Liliidae [= monocotyledons ] of class Magnoliopsida [= dicotyledons] and used this circumscription:

Angiosperm Phylogeny Group

The APG system (1998) also placed the order in the clade monocots, but with a slightly different circumscription (missing the family Corsiaceae):

The APG II system (2003) places this order in the clade monocots and uses this circumscription:

APG III (2009) uses this circumscription:

Phylogeny

According to the APWeb, the families of Liliales are related as follows:

Liliales

Corsiaceae

Campynemataceae


branch with 50-80% support

Melanthiaceae


branch with 50-80% support

Petermanniaceae

Colchicaceae

Luzuriagaceae

Alstroemeriaceae


Rhipogonaceae

Philesiaceae

Smilacaceae

Liliaceae






Distribution and habitat

Widely distributed but most commonly found in subtropical and temperate regions, especially the Northern Hemisphere. Since many species are cultivated they have been introduced in many regions and consequently worldwide, and a number have subsequently escaped and naturalised.

Uses

Liliales form important sources of food and pharmaceuticals as well as playing a significant role in horticulture and floriculture.

References

Bibliography

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