(Named tetracantha from the four spines commonly present)
How to identify and how it grows
The Popular Cholla is a loose irregular growth about four feet tall with several stems coming from the base, but not jointed. The brownish spicules are formed in bundles. There are from one to four spines, all less than an inch long, slender and stiff and brownish or light brownish gray, with one spine longer and stouter than the others, and covered with thin straw-colored sheaths. The flowers are of a pale yellow-green suffused with purplish tints, and open in the afternoon. The fruit is about one inch long and smooth, elliptical, and orange-red.
How to grow
This species may be transplanted at any season, or cuttings may be planted early in spring, in sandy or gravelly soil and watered monthly with light irrigation. The cuttings are less certain to grow. Plants grow also quite readily from seed. They are not injured by twenty-five degrees of frost and grow outdoors or in; in colder weather than this they should be given protection outside.
Prolific Tree Cholla (Opuntia arbuscula)
(The name arbuscula means “a small tree”)
How to identify and how it grows
Arbuscula, or the Prolific Tree Cholla, grows from three to eight feet tall and has a short stout trunk three to six inches in diameter. There are several branches which are intricately arranged, forming a rounded head from six to ten feet across; the gray-brown bark is coarse and fissured. The branch-joints are from two to ten inches long or longer, and are bright green. The light brownish spicules form as a small tuft. Usually only one or two spines are present, sometimes none at all, less than two inches long when they occur, bent, slender, needlelike, and a dull straw or brown. The thorns are covered with thin, amber, or brownish, loose, translucent sheaths. The flowers are a greenish yellow suffused with red and appear in dense clusters at the tips of the joints; they are produced at the ends of last year’s fruit. This often forms a chainlike cycle. The fruit is bright green and nearly smooth. This dwarf tree or shrub grows in the sandy desert areas and flood plains of southern Arizona and adjacent Mexico.