This Website identifies over 100 opuntiads of the United States by providing descriptions of each species as well as photographic documentation; often photographs are presented from winter, spring, summer, and fall because their appearance can vary in the different seasons. A group of experts (Who are we?) verifies all the information in this Website, and our editors make sure information is presented clearly.
Someone somewhere tucked almost any large Opuntia species in the United States into O. engelmannii. Similarly, smaller species were lumped with O. phaeacantha or O. polyacantha. Even Cylindropuntia and Grusonia were lumped into the genus Opuntia. This lumping created large difficulty in identifying the various opuntiads, and we hope this Website will assist in understanding, studying, and enjoying this group of plants.
Of the many opuntiads in the USA, some look superficially alike and some have even been forgotten; even botanists confuse them with each other and don’t know there are so many species. But they have different bloom times, consistently identifiable fruits, normally don’t interpollinate, and are restricted to specific habitats. Early botanists identified them and understood their uniqueness, and we use those historic records along with field studies to identify them, their differences, and their similarities.
Opuntiads Web is concerned with three genera: Opuntia, Cylindropuntia, and Grusonia; these plants have jointed stems called cladodes that may be flat or cylindrical. Cladodes conduct photosynthesis and are green, but cladodes are not leaves, they are stems. Like many stems, cladodes branch and have flowers and leaves. Opuntiad leaves range from less than an eighth of an inch long to an inch or more; they often go unnoticed due to their small size and because they fall from the cladodes quickly.
Like other cacti, opuntiads have areoles, which are small circular regions on cladodes; flowers, spines; new cladodes and flowers grow from areoles. Areoles are spread out over cladodes and often seem like spots or dots.
Cladodes are spiny, but in addition to spines, cladodes have glochids. Just as spines evolved from leaves, glochids did too; in fact, glochids are just tiny spines. Cladodes are difficult to handle because glochids break away and puncture skin easily. The tiny glochids burrow under the skin and cause irritation, pain, and swelling. Glochids cluster at areoles in great numbers.