Colorado hookless Cactus

The Colorado hookless cactus is a barrel shaped cactus that ranges from 1.2 to 4.8 inches (in.) (3 to 12 centimeters (cm)) tall, with exceptional plants up to 12 in. (30 cm) tall. Stems range from 1.6 to 3.6 in. (4 to 9 cm) in diameter. The stems have 8 to 15 (typically 12 or 13) ribs that extend from the ground to the tip of the plant. Along the ribs are areoles (small, cushion-like areas) with hooked spines radiating out (Heil and Porter 2004). There are two types of spines, radial and central, defined by the size and position on the plant (see Figure 1) (74 FR 47112, September 15, 2009). The 2 to 12 radial spines are located around the margin of the areole, extending in a plane parallel to the body of the plant. The radial spines are white or gray to light brown. They are up to 0.67 in. (17 millimeters (mm)) long, and less than 0.04 in. (1 mm) in diameter. The one to five central spines (usually three) are 0.5 to 2.0 in. (12 to 50 mm) long, are generally longer than radial spines, and extend from the center of the areole. The central spines include abaxial and lateral forms. Abaxial spines are typically single, point toward the top of the plant, and are noticeably bent at the tip at an angle usually less than 90 degrees. Lateral spines are usually present in pairs on either side of the abaxial spine, but are more or less straight and diverge from the abaxial spine at an acute angle (usually 20 to 50 degrees).The flowers are usually funnel-shaped, but sometimes bell-shaped. They usually have pink to violet tepals (petal-like flower parts not differentiated into petals and sepals) with yellow stamens (the male reproductive organ of the flower), and are 1.2 to 2.4 in. (3 to 6 cm) long and 1.2 to 2 in. (3 to 5 cm) in diameter (74 FR 47112, September 15, 2009). The fruit is short, barrel-shaped 0.31 to 0.47 in. (8 to 12 mm) wide, and 0.35 to 1.2 in. (9 to 30 mm) long.