Jacaranda subalpina grows to between to tall. The leaves are 25 to 45 cm in length and bipinnate, having between 11 and 23 pinnae and 17 to 23 leaflets. Leaflets are 0.8 to 4 cm long, 0.4 to 1.8 cm wide and "narrowly elliptic or oblong" in shape. The tops of the leaflets are dark green and the underside is "greenish gray" with sparse finehairs. The calyxcurvesinward in a funnel shape. The flowers have purple petals and a whitethroat, and are 4.5 to 6.5 cm long and 3 to 5 cm wide at the mouth. The fruit is "subwoody", growing 5 to 6.5 cm long and 2.6 to 3.5 cm wide.