Sunday, June 29, 2008

Prickly Pear

What’s blooming in the area: Catalpa, tamarix, tea and miniature roses, Apache plume, cholla, four-wing saltbush, Russian sage, trumpet creeper, honeysuckle, silver lace vine, lilies, fern-leaf globemallow, alfalfa, white sweet clover, oxalis, milkwort, velvetweed, wild licorice, yellow and white evening primroses, scarlet beeblossom, larkspur, bindweed, milkweed, buffalo gourd, goat’s beard, hawkweed, plains paper flower, Hopi tea, hairy golden aster; sacaton and rice grass; alfalfa cut and drying; corn up.

What’s blooming in my garden, looking north: Dr. Huey rose, red hot poker, golden spur columbine, coral beardtongue, hartweig, butterfly weed, yellow flax, chocolate flower, fern-leaf yarrow, blanket flower, coreopsis, anthemis, black-eyed Susan, Mexican hat.

Looking east: Floribunda rose, hollyhock, Maltese cross, bouncing Bess, snow-in-summer, pink, sea pink, coral bells, California poppy, winecup, sidalcea, rock rose, pink evening primrose, Saint John’s wort; tomatillo buds.

Looking south: Blaze, rugosa and rugosa hybrid roses, sweet pea, daylily; first raspberry.

Looking west: Purple beardtongue, Rumanian sage, catmint, ladybells, flax, speedwell, purple ice plant; sea lavender buds.

Bedding plants: Snapdragon, sweet alyssum, petunia, moss rose, Dahlberg daisy, gazania.

Inside: Aptenia, zonal geranium.

Animal sightings: Gecko, hummingbird, cabbage butterfly, hummingbird moth on golden columbine, bees on catmint, ants, grasshoppers; birds and crickets heard but not seen.

Weather: Temperature extremes moderated by late afternoon clouds that sometimes dropped water. However, even Monday, not enough fell to dampen the native ground where June grass that came up in unexpected places in the winter wet is now dead or dying. Last useful rain 6/5/08; 15:54 hours of daylight today.

Weekly update: One thing that’s always mystified me is why the prickly pear here are so unhealthy. In west Texas, they grow in great mounds along fences with bright yellow flowers that can be seen from the road much of the summer; mine have lumpy, faded-green surfaces with bite marks and black edges, shriveled pads and broken off segments baking in the sun.

The pale yellow flowers with their lemon-green pistils are elusive: they open mid-morning and disappear by mid-afternoon. The cacti run rampant in town near the river, but I’ve never spotted a flower there. Last Saturday, I saw a clump blooming under trees away from the orchards and others were aging into apricot out on the prairie. In my backyard, I espied one flower in the morning; the next day I searched, and nothing despite the buds. Even so, I’m sure there’ll be fruit later this summer.

One difference between Potosi and Española could be the species. Both are probably Opuntia engelmannii, but the ones here most likely are a subspecies, also engelmannii. In parts of west Texas where I drove they could have been lindheimeri. Around Abilene, they could have been either, but if engelmannii, their flowers may have been brighter from the lower altitude, greater water, different soils, and more southern latitude.

So far as I know none of the known predators are attacking my plants. The cactus moth wasn’t even seen in this country until 1989 in Big Pine Key, Florida. Peter Stiling says it had moved into South Carolina by 2002, but was still only a fear in Arizona and México where Opuntia species are grown commercially for food and ornamentation. My plants were unhealthy when I moved here in 1991.

The cactus borer sounds more likely. The adults bark the edges and lay their eggs inside the openings in the pads. When the larvae begin tunneling, a greenish-yellow liquid oozes out and accumulates on the junction with the lower pad where it turns black. However, the nondescript moth usually prefers less daunting specimens with spines singed by fire and also attacks cholla, which show no signs of siege.

That leaves the rabbit. Cottontails of all sorts and black-tailed jacks will eat whatever prickly pear grows in their range. The cacti are high in soluble carbohydrates, but low in protein and other nutrients. Around San Angelo, southwest of Potosi, Darrell Ueckert found the Lindheimer was 60% to 80% water depending on conditions.

Near Jornada del Meurto, a New Mexico State research team noticed the desert cottontail and black-tailed jack rabbit were fairly selective with the local prickly pear, eating more during the dry season when other forbs weren’t available. They preferred clumps that had at least three pads, and avoided large piles. They also left young growth alone for at least six months.

My experience seems closer to that of Ueckert who couldn’t establish a spineless prickly pear in west Texas because they were too heavily grazed by jack rabbits. The cottontails who leave their droppings near my destroyed plants let the plants grow a few pads, then nibble them before they can establish clumps that could protect themselves with longer spines and more oxalic acid. Naturally, the flowers I rarely see would appear next year on this year’s destroyed growth.

It seems I’ve inherited the typical dryland ecosystem that comes with the overgrazed open land rabbits prefer. Still, it’s curious to live in near desert conditions and not have the quintessential desert flower.

Hoffman, M. T., C. D. James, G. I. H. Kerley and W. G. Whitford. "Rabbit Herbivory and Its Effect on Cladode, Flower and Fruit Production of Opuntia violacea var macrocentra (Cactaceae) in the Northern Chihuahuan Desert, New Mexico," The Southwestern Naturalist, 38:309-315:1993.

Stiling, Peter. "Potential Non-target Effects of a Biological Control Agent, Prickly Pear Moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), in North America, and Possible Management Actions," Biological Invasions 4:273-281:2002.

Ueckert, Darrell N. "Pricklypear Ecology,"1997, available on-line.

Photograph: Nibbled prickly pear blooming on scrub land near the arroyo, 21 June 2008; picture taken mid-afternoon when the flower was aging to peach.

No comments: