The Most Common Cacti

Columnar

• Columnar species of cactus are much taller than they are wide. The tall cylindrical stems of columnar cacti have vertical ribs, or pleats, and range from the small (those of the Pygmaeocereus genus) to the very tall (saguaro). Columnar cacti require more nitrogen and water than most globular cacti, but can be robust growers. They may not produce flowers for several years, however, and blooms are more common in columnar cacti grown in the ground or in pots that have become too small for the plant's roots.

Barrel

• Specimens from the Ferocactus genus "Barrel," named for their resemblance to a barrel laying on its side, are wider than they are tall, with vertical ribs similar to those of cacti in the columnar genus. Although they can be grown from seed, they're slow-growing. A 4-year-old barrel cactus, for example, may be only 3 inches high and wide. Barrel cacti expand in rain, to absorb the water into their spongy interior tissue, then shrink during periods of drought, utilizing the absorbed water. Barrel cacti bloom late in the growing season with large, bright-orange flowers on top. The fishhook barrel cactus is the most common in this genus, with Arizona and California barrel cacti also frequently grown.

Cholla

• Cacti of the Opuntia genus "Cholla" have branches, or stems, that have segmented joints. Cholla cacti have tubercles that develop into sharp spikes, but the spikes have a papery sheath around them, making them unlike those of any other cacti genus. Cholla cacti are often viewed as houseplants because of their unusual appearance, easy care and multiple flowers. The most-common varieties are Christmas, teddy bear, chain fruit, pencil and staghorn. The prickly pear cactus is also classified as a cholla because of its long, jointed stems and large, flat pads.

Pincushion

• Mammillaria, or "Pincushion," cacti at first glance appear similar to barrel cacti, but lack the vertical ribs of barrel cacti. Usually growing less than 6 inches tall, pincushion cacti are covered with spines, often hook-shaped but can also be straight. They bloom in early summer with an attractive flower, or flowers, that can be large or small and range in color from light yellow to deep magenta, depending on the species. Common pincushion varieties are fishhook, spinystar and ball.