Araliaceae

The Araliaceae are a family of flowering plants composed of about 43 genera and around 1500 species consisting of primarily woody plants and some herbaceous plants. The morphology of Araliaceae varies widely, but it is predominantly distinguishable based on its woody habit, tropical distribution, and the presence of simple umbels.

There are numerous plants of economic importance. Some genera, such as ''Hedera'' (the ivies), ''Fatsia'' (Japanese aralias) and ''Schefflera'' (the umbrella trees)'', ''are used as ornamental foliage plants. The family also includes ''Panax ginseng'', the root of which is ginseng, used in traditional Chinese medicine.

Overview

The morphology of Araliaceae varies widely. Many studies have found that there is no unifying characteristic capable of classifying the family. In general, Araliaceae species have large, usually alternate leaves, often with aromatic ethereal oils, five-petaled flowers, two to five carpels, simple umbels, and berries without carpophores or oil cavities. Some taxa carry prickles, and the family is often woody but also occasionally herbaceous. While Araliaceae is predominantly a tropical family, some taxa are also endemic to temperate climates. They are found in the Americas, Eurasia, Africa, Australia, New Zealand, New Caledonia, and Pacific islands.

Some examples of Araliaceae include the angelica tree (''Aralia spinosa''), the devil's club (''Oplopanax horridus''), ivy (''Hedera'' spp., including'' H. helix''), and herbs such as ginseng (''Panax'' spp.). Leaves are sometimes lauroid (resembling ''Laurus'') and are simple to compound; when compound, they are ternate, pinnate, or palmate.

Araliaceae are found in the pluvial montane forest, very humid montane forest, and humid lowland river forest regions. They are also present in laurel forest, cloud forest, and warm, humid habitats.

Taxonomy and Systematics

Araliaceae is one of six angiosperm families recognized by APG IV belonging to the Apiales, an order within the Asterids. Araliaceae is accepted to be a monophyletic branch within the Apiales.

Within Araliaceae, there are four accepted groups:

1. The Greater ''Raukaua'' group, sister to the rest of the main Araliaceae clades.

2. The ''Aralia-Panax'' group, consisting of the mostly monophyletic genera ''Aralia'' and ''Panax.''

3. The ''Polyscias-Pseudopanax'' group, sister to both genus ''Cussonia'' and the Asian Palmate group.

4. The Asian Palmate group, largest of the groups representing Araliaceae.

There are also multiple taxa that float around these groups, but are not within them.

The generic level classification of the Araliaceae has been unstable and remains under study. For instance, numerous genera have been synonymized under ''Schefflera'', within which about half the species within Araliaceae are placed. Recent molecular phylogenies have shown that this large pantropical genus is polyphyletic and some believe it should be divided again into several genera, though these would probably not correspond with the previously recognized genera.

Recent molecular systematics techniques have made major improvements into understanding of the evolution of Araliaceae, leading to the knowledge existing today. Due to widely varying morphological characters, the systematics of Araliaceae had been largely debated over the past century, especially in the absence of molecular evidence. For instance, Araliaceae were previously merged into the closely related Apiaceae (synonym: Umbelliferae) in some taxonomic treatments that have since been rejected. The family is closely related to the Apiaceae and Pittosporaceae, but some of the exact boundaries between Araliaceae and the other families of Apiales are still uncertain and are currently being examined.

One example group that proved problematic for Araliaceae systematics is subfamily Hydrocotyloideae. Molecular phylogenies suggest at least some of the genera traditionally spanning across Araliaceae and Apiaceae as Hydrocotyloideae appear to be more closely related to Araliaceae. It has been recommended that subfamily Hydrocotyloideae be narrowed to just include genera ''Hydrocotyle,'' ''Trachymene,'' and ''Harmsiopanax'' to form a monophyletic group in Araliaceae.

Subfamilies and genera

;Subfamily Aralioideae
* '' Anakasia''
* ''Aralia''
* ''Astrotricha''
* '' Brassaiopsis''
* ''Cephalaralia''
* ''Cheirodendron''
* '' Chengiopanax''
* ''Cussonia''
* ''Dendropanax''
* '' Eleutherococcus''
* × ''Fatshedera''
* ''Fatsia''
* ''Gamblea''
* ''Harmsiopanax''
* ''Hedera''
* ''Heteropanax''
* ''Kalopanax''
* '' Macropanax''
* ''Megalopanax''
* '' Merrilliopanax''
* ''Meryta''
* ''Metapanax''
* ''Motherwellia''
* ''Neocussonia''
* ''Oplopanax''
* '' Oreopanax''
* '' Osmoxylon''
* ''Panax''
* ''Paleopanax''
* ''Plerandra''
* ''Polyscias'' (includes former genera ''Arthrophyllum'', '' Cuphocarpus'' as subgenera)
* ''Pseudopanax''
* ''Raukaua''
* ''Schefflera''
* '' Sciadodendron''
* ''Seemannaralia''
* ''Sinopanax''
* '' Stilbocarpa''
* ''Tetrapanax''
* ''Trevesia''
* ''Woodburnia''
;Subfamily Hydrocotyloideae
* ''Hydrocotyle''
* ''Trachymene''
;Subfamily ''incertae sedis''
* †'' Araliaceoipollenites'' (fossil pollen)

File:Scheflera1.jpg, ''Schefflera arboricola''
File:Oplopanax horridus0.jpg, ''Oplopanax horridus''
File:Eleutherococcus-sieboldianus.JPG, ''Eleutherococcus sieboldianus''
File:Starr 070515-7041 Osmoxylon lineare.jpg, ''Osmoxylon lineare''
File:Illustration Hydrocotyle vulgaris0.jpg, ''Hydrocotyle vulgaris''
File:Starr 010419-0021 Hedera helix.jpg, ''Hedera helix''
File:Aralia spinosa, Georgia, USA.jpg, ''Aralia spinosa''

See also

* List of foliage plant diseases (Araliaceae)

References

External links

* Frodin, D. G. and R. Govaerts. 2004. World Checklist and Bibliography of Araliaceae. Kew Publishing.

Araliaceae Resource Center


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{{Taxonbar, from=Q193335

Asterid families
Extant Eocene first appearances