The Texas rainbow (Echinocereus pectinatus) is one of 2 rainbow cacti that have ribbed stems (not tubercles) with very closely spaced areoles. The spines from these areoles often almost completely cover the stem, providing protection from intense sun. As the plants grow from the top of the stem the spines that they produce in different years or different times of the year can have different colours. This results in a banded pattern of spine colours - hence the name "rainbow" cactus.
There are several types of rainbow cactus in different desert regions, but the Texas rainbow is common in the Chihuahuan Desert of Mexico and in restricted regions of southern New Mexico and Texas.
Either of two spiny cylindrical varieties of cactus of the southwestern United States and Mexico, Echinocereus pectinatus var. neomexicanus, having yellow flowers, or E. pectinatus var. rigidissimus, having showy magenta flowers.
Alternate name: Comb Hedgehog
Family: Cactaceae, Cactus
Description A low, cylindrical cactus girdled from top to bottom by bands of colorful spines, pink, gray, pale yellow, brown, or white; flowers pink, rose, lavender, or yellow.
Flowers: 2 1/2-51/2" (6.5-14 cm) wide, 1 or few per plant; petals many.
Stems: To 4" (10 cm) wide; ribs 15-22.
Spines: To 1/2" (1.5 cm) long, slender, in close clusters; point at which they attach is a vertical oval.
Fruit: Plump, greenish, with spines eventually dropping off.
Height: 4-12" (10-30 cm).
Flower June-August.
Habitat Rocky slopes and flats, commonly on limestone.
Range Central and southern Arizona east to western Texas and south to northern Mexico.
Discussion The banded colors of spines explain the name Rainbow Cactus. The strikingly beautiful flowers seem far too large for the plant.
