Fabales
Order of flowering plants including legumes and milkworts.
Fabales is an order of flowering plants belonging to the rosid group within the eudicots, according to the Angiosperm Phylogeny Group II system. This order comprises four families: Fabaceae (legumes), Quillajaceae, Polygalaceae (milkworts), and Surianaceae. The Fabaceae family, which is the third-largest plant family globally, accounts for the vast majority of the order's diversity, while the other families contribute only a small portion. Most research on Fabales concentrates on Fabaceae, driven by its extensive biological variety and its significance as a source of food crops. The Polygalaceae family is also relatively well-studied, partly because of the large genus *Polygala* and because many of its members serve as food plants for various butterfly and moth species. Although molecular phylogenetic studies strongly support the grouping of these families into Fabales, questions remain about the morphological relationships of Quillajaceae and Surianaceae to the rest of the order, largely due to limited research on those families. Molecular clock estimates indicate that the lineage leading to Fabales diverged from other plants roughly 101 million years ago.
In terms of distribution, Fabales is a cosmopolitan order found worldwide, though only the subfamily Papilionoideae (also called Faboideae) of the Fabaceae is widely spread across the northern part of the North Temperate Zone.
- classification_system
- APG II
- included_families
- Fabaceae, Quillajaceae, Polygalaceae, Surianaceae
- largest_family
- Fabaceae (third-largest plant family)
- distribution
- cosmopolitan, except subfamily Papilionoideae well dispersed in northern North Temperate Zone
Lore & Background
The order Fabales, as defined by the Angiosperm Phylogeny Group II system, encompasses four families: Fabaceae (the legumes, including subfamilies Caesalpinioideae, Mimosoideae, and Faboideae), Quillajaceae, Polygalaceae (the milkworts, which also includes the families Diclidantheraceae, Moutabeaceae, and Xanthophyllaceae), and Surianaceae. The vast majority of the order’s diversity is concentrated within Fabaceae, which is the third-largest plant family globally. Research on Fabales heavily emphasizes Fabaceae, driven by its immense biological variety and its significance as a source of food plants. The Polygalaceae are also relatively well-studied, partly because of the extensive diversity within the genus *Polygala* and because many members serve as food for various Lepidoptera species. In contrast, the Quillajaceae and Surianaceae remain poorly researched, leading to unresolved questions about their morphological relationships to the rest of the order, even though molecular phylogenetic data strongly supports the grouping. Historically, the Cronquist system restricted Fabales to only the Fabaceae, placing Polygalaceae in its own order (Polygalales) and assigning Quillajaceae and Surianaceae to Rosales. The Dahlgren system, however, placed Fabales within the superorder Fabiflorae, comprising three families that correspond to the subfamilies of Fabaceae recognized in the APG II system. Molecular clock estimates indicate that the lineage leading to Fabales diverged from other plants approximately 101 million years ago. Geographically, Fabales are cosmopolitan, though only the subfamily Papilionoideae (Faboideae) of the Fabaceae is widely distributed throughout the northern part of the North Temperate Zone.
Reader's Guide
Fabales is significant as an order that includes the Fabaceae, the third-largest plant family, which contains most of the order's diversity and is heavily researched for its biological diversity and role as food plants. The Polygalaceae are also well studied, partly due to the large genus Polygala and their use as food plants for Lepidoptera. The cosmopolitan distribution of Fabales is notable, though only the subfamily Papilionoideae is well dispersed in the northern North Temperate Zone. The order's classification has varied among systems, with APG II providing a broader circumscription than Cronquist, reflecting ongoing taxonomic refinement.
Did You Know?
- The Fabales order includes the families Fabaceae, Quillajaceae, Polygalaceae, and Surianaceae.
- Under the Cronquist system, Fabales contained only the family Fabaceae.
- Only the subfamily Papilionoideae of Fabaceae is well dispersed throughout the northern part of the North Temperate Zone.
More in Plant Families & Taxonomy 1-24
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