Opuntia fragilis

(brittle prickly-pear cactus)

.

Drawing on left from Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 2: 573. Photo taken in the San Juan Islands by Carson Sprenger, 2006.

Range

Opuntia fragilis makes its home from British Columbia

all the way east to Michigan, and as far south as Texas. ⁽¹⁾

Elevation in Washington State: 14 - 4500 ft (4 – 1372 m).

Local occurrence

According to the Washington Natural Heritage Program, there are only 10 known occurrences of O. fragilis in Washington. Despite this small number of sitings, it is recorded to have been seen in all of the following counties: Grant, Okanogan, Ferry, Clallam, San Juan, Skagit, Whatcom, Stevens, Douglas, Kittitas and Yakima. Some of these populations, however, may no longer be present. ⁽⁴⁾

Habitat preferences

This species does well in open, exposed locations and cannot persist in shady conditions. Much of its habitat has been lost due to tree encroachment (fire suppression & exclusion) and the introduction of invasive species. ⁽⁴⁾

Plant strategy

Able to grow on south-facing rocky outcrops, like many cactus species, O. fragilis is a stress tolerator. Some studies have found that it reproduces almost exclusively asexually, by segments breaking off and rolling away, being carried by animals, or even floating and relocating via water. Its species name “fragilis” is a nod to the ease in which terminal segments break off from the main plant. ⁽³⁾ This strategy can be a nuisance to humans and animals alike. It is perhaps for this reason that it is listed as a noxious weed in Nebraska. ⁽²⁾ The yellow flowers bloom very briefly sometime between May and July depending on location. ⁽³⁾

Associated species

Due to its wide range, O. fragilis is associated with a wide variety of species. In western Washington, it is usually found in open, grassland areas while on the east side it is commonly associated with ponderosa pine and bunchgrass communities. ⁽⁴⁾

May be collected as:

O. fragilis may not be collected in Washington.

Seed germination

If you are so lucky as to 1) find a fruiting plant, 2) find fruit with viable seed, and 3) live in a state where you can collect O. fragilis, the following method has been suggested. Lightly sand the surface of the seed before stratification. Place in the fridge for 5 weeks and then set out in 68º F for germination. ⁽³⁾

Propagation recommendations

Make friends with someone from Nebraska. Have that friend send you a vegetative segment (also known as a cladode) of the plant; stick the cut-off portion in well-drained, sandy soil. Water sparingly and be patient.

Soil or medium requirements

Sandy, well-drained soil is a must.

Sources cited

(1) Burke Museum Herbarium Image Collection.

http://biology.burke.washington.edu/herbarium/imagecollection.php May 23, 2006.

(2) PLANT Database. http://plants.usda.gov/java/profile?symbol=OPFR. May 24, 2006.

(3) Ribbens, Erc M.D. Opuntia fragilis (Nuttall) Haworth (Cactaceae): Reproductive Ecology.

http://www.wiu.edu/users/mfer1/pubs/OpFrInfo/reproduction.htm. May 24, 2006

(4) Washington Natural Heritage Program website: http://www.dnr.wa.gov/nhp/refdesk/fguide/htm/fsp_ascu.htm May 25, 2006

Data compiled by

Samantha Martin Sprenger

May 25, 2006