Desert Willow. Scientific Name: Chilopsis linearis. Desert-willow is a 15-40 ft., slender-twigged, small tree or large shrub, often with leaning, twisting trunk and open, spreading crown. Leaves are deciduous, willow-like, light green, both opposite and alternate, 4–12 inches long and 1/3 inch wide. The blossom is funnel-shaped, 1–1 1/2 inches long, spreading at the opening into 5 ruffled, petal-like lobes. The flower is dark pink or purple.