Opuntia polyacantha is a common species of cactus

Cactus

A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...

 known by the common names plains pricklypear, hairspine cactus, panhandle pricklypear, and starvation pricklypear. It is native to North America, where it is widespread in western Canada, the central and western United States, and northern Mexico.

This cactus grows up to 40 centimetres (15.7 in) tall. It forms low mats of pads which may be several meters wide. Its succulent green pads are oval or circular and reach 27 by wide. Its areole

Areole

Areoles are an important diagnostic feature of cacti, and identify them as a family distinct from other succulent plants. The areoles on cacti are clearly visible; they generally appear as small light- to dark-colored bumps, out of which grow clusters of spines...

s are tipped with woolly brown fibers and glochid

Glochid

Glochids are hair-like spines or short prickles, generally barbed, found on the areoles of cacti in the sub-family Opuntioideae. Cactus glochids easily detach from the plant and lodge in the skin, causing irritation upon contact...

s. Many of the areoles have spines

Thorns, spines, and prickles

In botanical morphology, thorns, spines, and prickles are hard structures with sharp, or at least pointed, ends. In spite of this common feature, they differ in their growth and development on the plant; they are modified versions of different plant organs, stems, stipules, leaf veins, or hairs...

 which are quite variable in size and shape. They may be 0.4 to 18.5 cm (0.15748031496063 to 7.3 in) in length, stout or thin, straight or curling, and any of a variety of colors. The flowers are 2.5 to 4 cm (0.984251968503937 to 1.6 in) long and may be yellow or magenta

Magenta

Magenta is a color evoked by light stronger in blue and red wavelengths than in yellowish-green wavelengths . In light experiments, magenta can be produced by removing the lime-green wavelengths from white light...

 in color. The fruit is cylindrical, brownish, dry and spiny. The cactus reproduces by seed, by layering

Layering

Layering is a means of plant propagation in which a portion of an aerial stem grows roots while still attached to the parent plant and then detaches as an independent plant. Layering has evolved as a common means of vegetative propagation of numerous species in natural environments...

, and by resprouting from detached segments.

This cactus grows in a wide variety of habitat types, including sagebrush

Sagebrush

Sagebrush is a common name of a number of shrubby plant species in the genus Artemisia native to western North America;Or, the sagebrush steppe ecoregion, having one or more kinds of sagebrush, bunchgrasses and others;...

, Ponderosa pine forest, prairie, savanna, shrublands

Temperate grasslands, savannas, and shrublands

Temperate grasslands, savannas, and shrublands is a terrestrial biome whose predominant vegetation consists of grasses and/or shrubs. The climate is temperate and semi-arid to semi-humid....

, shrubsteppe, chaparral

Chaparral

Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...

, pinyon-juniper woodland

Pinyon-juniper woodland

A Pinyon-juniper woodland is a forest type characteristic of many parts the Western United States, often in higher elevations of desert ecoregions.-Locations:...

, and scrub

Shrubland

Shrubland, scrubland, scrub or brush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity...

.

This pricklypear provides food for many types of animals. It provides over half the winter food for the black-tailed prairie dog

Black-tailed Prairie Dog

The black-tailed prairie dog , is a rodent of the family Sciuridae found in the Great Plains of North America from about the USA-Canada border to the USA-Mexico border. Unlike some other prairie dogs, these animals do not truly hibernate. The black-tailed prairie dog can be seen aboveground in...

 in one area. Pronghorn

Pronghorn

The pronghorn is a species of artiodactyl mammal endemic to interior western and central North America. Though not an antelope, it is often known colloquially in North America as the prong buck, pronghorn antelope, or simply antelope, as it closely resembles the true antelopes of the Old World and...

 eat it, especially after the spines are burned off in wildfire

Wildfire

A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...

s. Ranchers intentionally burn stands of the plant to make it palatable for livestock when little other food is available. It will also grow in waste areas where good forage will not take hold. In fact, an abundance of the cactus indicates land that is poor in quality.

Several insects attack the cactus, including the cactus moth Melitara dentata

Melitara dentata

The North American Cactus Moth is a moth of the Pyralidae family. It is native to western North America, where it is widespread from Alberta to southern Arizona and central Texas. It is an introduced species in Hawaii....

, the blue cactus borer Olycella subumbrella, and the cactus bug Chelinidea vittiger.

External links

• Opuntia polyacantha. CalPhotos Photo Gallery