SPECIES: Opuntia fragilis
© 2005 Jerry Murray
Infrataxa: Based upon differences in distribution and plant size, some systematists recognize 2 varieties of brittle pricklypear [9,38,39,50,78]:
Opuntia fragilis var. brachyarthra (Engelm. & Bigelow) Coult, little pricklypear
Opuntia fragilis var. fragilis, pygmy pricklypear
Hybrids: Brittle pricklypear hybridizes with plains pricklypear (O. polyacantha) and grizzlybear pricklypear (O. erinacea) .LIFE FORM:
Varieties: Pygmy pricklypear occurs throughout the general range of brittle pricklypear. Little pricklypear occurs in Colorado, New Mexico, Arizona, and Utah .ECOSYSTEMS :
Brittle pricklypear is commonly found in upland grasslands dominated by various bunchgrasses including blue grama (Bouteloua gracilis), buffalo grass (Buchloe dactyloides), Sandberg bluegrass (Poa secunda), bluebunch wheatgrass (Pseudoroegneria spicata), western wheatgrass (Pascopyrum smithii), and green needlegrass (Nassella viridula) [31,46,55,72,81].
In tallgrass prairies dominated by big bluestem (Andropogon gerardii) and little bluestem (Schizachyrium scoparium), brittle pricklypear occurs but is an uncommon associate [30,81].
Brittle pricklypear is a common associate in a wide variety of habitat types dominated by big sagebrush (Artemisia tridentata) and silver sagebrush (A. cana). It also occurs as an associate in various shrub communities including those dominated by greasewood (Sarcobatus vermiculatus), shadscale saltbush (Atriplex confertifolia), and blackbrush (Coleogyne ramosissima) [14,31,49,72].
In the Sandhills region of Colorado and Nebraska, brittle pricklypear is commonly found in communities dominated by sand sagebrush (Artemisia filifolia), prairie sandreed (Calamovilfa longifolia), sand bluestem (Andropogon gerardii var. paucipilus), hairy grama (Bouteloua hirsuta), and sandhill muhly (Muhlenbergia pungens) [58,62].
Brittle pricklypear occurs in various woodland communities, notably dry ponderosa pine (Pinus ponderosa) communities, dry ponderosa pine-Douglas-fir (Pseudotsuga menziesii) habitat types, pinyon-juniper (P. edulis-Juniperus spp.) woodlands and Gambel oak (Quercus gambelii) thickets [1,51,77,79,80].
Publications that discuss plant communities in which brittle pricklypear occurs are listed below. The list is neither restrictive nor all inclusive.AZ [13,49]
Brittle pricklypear is a perennial native mat- or clump-forming cactus, usually 2 to 4 inches (5-10 cm) tall. The clumps or mats often exceed 12 inches (30 cm) in diameter. The succulent stem segments, or pads, are 0.5 to 5 inches (1.2-2.5 cm) wide and range in length from 0.8 to 2 inches (2-5 cm) for pygmy pricklypear and 2 to 2.8 inches (5-7cm) for little pricklypear. Aereoles on the pads give rise to 2 to 7 barbed spines that are 0.5 to 0.8 inch (1.2-2 cm) long for pygmy pricklypear and 0.8 to 1.2 inches (2-3) cm long for little pricklypear. Flowers are solitary, 1.2 to 2 inches (3-5 cm) long and broad. The fruit is a pear-shaped berry, 0.6 to 0.8 inch (1.5-2 cm) long, and is usually spiny. The seeds are glabrous, flattened, oblong to subcircular, and 0.2 inch (5 mm) in diameter. The root system is shallow and fibrous [9,21,50,68].
Brittle pricklypear is extremely tolerant of drought. It avoids drought damage by accumulating water in storage cells that contain mucilaginous materials with a strong water-retaining capacity .
RAUNKIAER  LIFE FORM:
Brittle pricklypear reproduces by seeds, layering, and sprouting from detached stem segments .
Breeding system: Brittle pricklypear is monoecious .
Pollination: Brittle pricklypear is pollinated by insects .
Seed production: Brittle pricklypear does not dependably flower every year in its northerly range, thus limiting seed production in these areas [9,48,79].
Seed dispersal: Seeds of brittle pricklypear are primarily spread when the fruits are eaten by frugivorous birds and small mammals. Fruits also readily attach to the fur and feathers of animals [8,68].
Seed banking: No information is available on this topic.
Germination: Germination rate is reportedly low for seeds of Opuntia species .
Seedling establishment/growth: Although the literature reports that brittle pricklypear regenerates by seeds , information is lacking on the specifics of seedling establishment and growth.
Asexual regeneration: Asexual reproduction occurs from detached pads which readily root even in the absence of water. The pads are primarily dispersed by attaching to animals by the barbed spines. The pads are also dispersed by gravity and by floating in water during heavy rains or snow melt. In the northerly range of brittle pricklypear, flowering can be rare and the plant may depend wholly on vegetative reproduction [9,48].SITE CHARACTERISTICS:
Brittle pricklypear is perhaps the most cold tolerant of all the cacti species, being able to survive on sites where the minimum winter temperatures can drop below -58 oF (-50 oC). The cactus avoids freeze damage by rapidly reducing the water content in cells during cold acclimation. The short stature of the plants allows brittle pricklypear to take advantage of the insulating effects of snow and the thermal environment at the soil surface. Brittle pricklypear also is able to withstand temperatures in excess of 131 oF (55 oC) [37,48].
Brittle pricklypear is most commonly found on rocky, sandy or gravely soils, but can also flourish on silty, loamy, or clayey soils. It is tolerant of salt-affected, alkaline, and solodized (dealkalized) soils [9,80,81].
The moisture regimes at which brittle pricklypear can be found are quite varied. For example, in British Columbia, brittle pricklypear occurs on sites ranging from very xeric to hygric .
The following table lists reported elevational ranges for brittle pricklypear:
|State or province||Elevation|
|AZ||6,500 to 7,500 feet (1,981-2,286 m) |
|CO||4,500 to 7,500 feet (1,372-2,286 m) |
|NM||4,500 to 8,000 feet (1,372-2,438 m) |
|UT||4,495 to 8,415 feet (1,370-2,565 m) |
|WA||14 to 4,500 feet (4-1,372 m) |
|BC||738 to 11,089 feet (225-3,380) |
Fire regimes: Brittle pricklypear occurs in plant communities with a wide range of fire frequencies, from less than 10 years for many prairie and grassland communities, to the 400 years possible for the Colorado pinyon (Pinus edulis) community. As of this writing (2005), fire ecology studies are lacking for brittle pricklypear. The following table provides fire return intervals for plant communities and ecosystems where brittle pricklypear occurs. For further information, see the FEIS review of the dominant species listed below.
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|bluestem prairie||Andropogon gerardii var. gerardii-Schizachyrium scoparium||<10 [43,56]|
|Nebraska sandhills prairie||Andropogon gerardii var. paucipilus-Schizachyrium scoparium||<10|
|bluestem-Sacahuista prairie||Andropogon littoralis-Spartina spartinae||<10 |
|silver sagebrush steppe||Artemisia cana||5-45 [29,57,83]|
|sagebrush steppe||Artemisia tridentata/Pseudoroegneria spicata||20-70 |
|basin big sagebrush||Artemisia tridentata var. tridentata||12-43 |
|mountain big sagebrush||Artemisia tridentata var. vaseyana||15-40 [4,16,54]|
|Wyoming big sagebrush||Artemisia tridentata var. wyomingensis||10-70 (40**) [74,84]|
|saltbush-greasewood||Atriplex confertifolia-Sarcobatus vermiculatus||<35 to <100 |
|desert grasslands||Bouteloua eriopoda and/or Pleuraphis mutica||10 to <100 [52,56]|
|plains grasslands||Bouteloua spp.||<35 [56,83]|
|blue grama-needle-and-thread grass-western wheatgrass||Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii||<35 [56,60,83]|
|blue grama-buffalo grass||Bouteloua gracilis-Buchloe dactyloides||<35 [56,83]|
|grama-galleta steppe||Bouteloua gracilis-Pleuraphis jamesii||<35 to <100|
|blue grama-tobosa prairie||Bouteloua gracilis-Pleuraphis mutica||<35 to <100 |
|blackbrush||Coleogyne ramosissima||<35 to <100|
|Rocky Mountain juniper||Juniperus scopulorum||<35 |
|wheatgrass plains grasslands||Pascopyrum smithii||<5-47+ [56,57,83]|
|pinyon-juniper||Pinus-Juniperus spp.||<35 |
|Colorado pinyon||Pinus edulis||10-400+ [22,26,41,56]|
|interior ponderosa pine*||Pinus ponderosa var. scopulorum||2-30 [3,6,47]|
|Arizona pine||Pinus ponderosa var. arizonica||2-15 [6,19,64]|
|mesquite||Prosopis glandulosa||<35 to <100 [52,56]|
|mesquite-buffalo grass||Prosopis glandulosa-Buchloe dactyloides||<35|
|Texas savanna||Prosopis glandulosa var. glandulosa||<10 |
|mountain grasslands||Pseudoroegneria spicata||3-40 (µ=10) [2,3]|
|oak-juniper woodland (Southwest)||Quercus-Juniperus spp.||<35 to <200 |
|blackland prairie||Schizachyrium scoparium-Nassella leucotricha||<10|
|Fayette prairie||Schizachyrium scoparium-Buchloe dactyloides||<10 |
|little bluestem-grama prairie||Schizachyrium scoparium-Bouteloua spp.||<35 |
Brittle pricklypear provides food for cactus-feeding insects including moths, bugs, and beetles. For a list of insect species that graze brittle pricklypear, see [8,15,76].
Palatability/nutritional value: Brittle pricklypear is low in nutritional value for livestock .
Cover value: No information is available on this topic.VALUE FOR REHABILITATION OF DISTURBED SITES:
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