Chilopsis is a genus of flowering plant, containing a single species, Chilopsis linearis. It is a small tree native to the southwestern United States and Mexico. Despite the common name Desert-willow, given because of its willow-like leaves, it is actually a member of the bignonia family Bignoniaceae. It is commonly seen in washes and along riverbanks at elevations below 1500 m in its range.
Ranging from 1.5 to as much as 8 meters in height, it can have the general appearance of either a shrub or a small tree. The linear curved leaves, ranging from 10-26 cm in length and 2-4 mm broad, are deciduous.
The flowers occur in a terminal panicle or raceme; the bloom starts in May, and progresses into September, with 2-4 flowers open at any one time. The calyx is about 8-14 mm, slightly inflated, and varying shades of purple, while the corolla is 2-5 cm, and with colors ranging from lavender to light pink. The throat and lower lip has a pattern of yellow ridges and purple lines, and the margins are crinkled. It is pollinated primarily by large bees in the family Apidae, such as carpenter bees, bumblebees, Anthophora, and Centris. The fruit is a linear pod up to 35 cm long, containing numerous winged seeds.
There are two subspecies:
It is cultivated for its large showy flowers, and tolerance of hot, dry climates. Although the natural growth is a very irregular shape, it can be readily pruned into a conventional tree shape. A number of cultivars have been selected, some (e.g. 'Rio Salado') with flowers of a dark and rich purple or magenta shades.
Chilopsis is closely related to the genus Catalpa and hybrids can be made between the two genera. The nothogeneric hybrid between Chilopsis linearis and Catalpa bignonioides has been named ×Chitalpa tashkentensis; as the name suggests, this hybrid was first raised in a botanic garden at Tashkent in Uzbekistan. It has broader leaves, up to 4 cm broad.