Arsenic Bush is a shrub or small tree to 3 m, native of Mexico.

The leaves are compound with usually 3-4 and occasionally 5 pairs of leaflets. The outermost ones are larger. There is no terminal leaflet.

Leaflets are paler on the underneath, relatively glosssy on the upper surface. The tip of the leaflets are pointed or rounded, the base of the leaflets are rounded or cuneate.

There are “nectaries” (gland secreting nectar) between all but the outermost pairs of leaflets.

Flowers have yellowish green to yellowish brown calyxes and bright yellow petals.

Photo: Robert Whyte

Mature fruit and foliage

Fruit are long pods, cylindrical or nearly so, divided into two parallel rows of cells.

Septemptrionalis means northern.