Orbexilum

Orbexilum, commonly called leather-root,^[2] is a genus of flowering plants in the legume family (Fabaceae). They are native to North America, where they are found in the United States and Mexico, south to Chiapas.^[3]

Orbexilum
Orbexilum pedunculatum
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Fabales
Family:	Fabaceae
Subfamily:	Faboideae
Tribe:	Psoraleeae
Genus:	Orbexilum Raf. (1832)[1]
Species
See text
Synonyms[1]
Rhytidomene Rydb. (1919)

This genus can be distinguished from other genera in the Psoraleeae by its "thick glabrous pod walls that are distinctively rugose and by [a] calyx that is scarcely accrescent."^[4]

Taxonomy

The genus was described by Constantine Samuel Rafinesque in 1832, with the type species O. latifolia, moved from Psoralea.^[5] (O. latifolia is now considered a synonym of O. onobrychis.^[6]) Rafinesque differentiated Orbexilum from Psoralea largely on the basis of features of the calyx.^[7]

Species

Orbexilum comprises the following species:^[1][4]

• Orbexilum chiapasanum B.L.Turner
• Orbexilum lupinellus (Michx.) Isely^{[note 1]}
• †Orbexilum macrophyllum (Rowlee) Rydb. – bigleaf scurfpea^[8]
• Orbexilum melanocarpum (Benth.) Rydb.
• Orbexilum oliganthum (Brandegee) B.L.Turner
• Orbexilum onobrychis (Nutt.) Rydb.
• Orbexilum pedunculatum (Mill.) Rydb.
• Orbexilum psoralioides (Walter) Vincent, syn. Orbexilum gracile (Torr. & A.Gray) B.L.Turner
• Orbexilum simplex (Nutt. ex Torr. & A.Gray) Rydb.
• †Orbexilum stipulatum (Torr. & A.Gray) Rydb.
• Orbexilum virgatum (Nutt.) Rydb.

Notes

1. The specific epithet is sometimes incorrectly spelled lupinellum, but is a noun in apposition, so is correctly spelled lupinellus.^[9]