Native to (or naturalized in) Oregon:
- Broadleaf evergreen tree or shrub; spiny, short trunked and a dense, wide spreading crown. It may reach a height of 30 ft (9 m) or more (the National Champion is 44 ft tall). In younger trees, the bark is gray, shiny, and smooth; in older trees the bark is broken open and scaly. Twigs are greenish, with a pair of slender, straight 1 cm thorns (spines) at each node. Leaves are alternate, pinnately compound, about 2.5-6 cm long, with 6-15 pairs of bluish-green leaflets, each 0.5-2 cm long, oblong, with a rounded tip, and short pointed base, and an entire margin. While usually evergreen, plants may lose their leaves during a long drought or if temperatures fall below 36 °F. Showy when in bloom. Flowers are pea-shaped with 5 unequal petals, which may be medium purple, magenta-red, white or pale pink. The fruit is a 5–7 cm long cylindrical pod covered with sticky hairs; light reddish brown when ripe and containing 1-5 shiny brown seeds.
- Full sun, well-drained soil, does not do well in sea side locations
- Hardy to USDA Zone 9 Found in southeastern California, southwestern Arizona and northwestern Mexico on gravelly or sandy mesas or rocky foothills of the desert.
- The wood is extremely heavy, 66 pounds/cu. ft with a specific gravity of 1.15 (sinks in water).
- Olney: Asa Gray named this monotypic genus to honor his friend Stephen Thayer Olney (1812-78), a business man and botanist of Rhode Island. tesota: an Native American name. The seeds of the plant were parched, ground lightly into a meal or roasted and eaten.