Pultenaea adunca is an erect, spindly shrub that typically grows to a height of. The leaves are needle-shaped, long and wide and hairy with stipules at the base. The flowers are yellow and red with red and yellow markings. Each flower is borne on a pedicel long with hairy bracteoles long at the base. The sepals are long and hairy. The standard petal is long and glabrous, the wings are long and the keel long. Flowering occurs in March and October and the fruit is an ovalpod.