Sunday, June 22, 2008

Rock Rose

What’s blooming in the area: Tea, miniature and shrub roses; Apache plume, tamarix, prickly pear, cholla, four-wing saltbush, trumpet creeper, honeysuckle, silver lace vine, daylily, fern-leaf globemallow, alfalfa, loco weed, oxalis, tumble mustard, velvetweed, white evening primrose, Indian paintbrush, bush morning glory, bindweed, milkweed, goat’s head, goat’s beard, hawkweed, plains paper flower, Hopi tea, hairy golden aster, native dandelion; brome, three-awn, sacaton and rice grass.

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

Looking east: Floribunda rose, hollyhock, Maltese cross, bouncing Bess, small-leaf soapwort, snow-in-summer, pink, sea pink, coral bells, winecup, rock rose, pink salvia, pink evening primrose, Mount Atlas daisy; buds on sidalcea.

Looking south: Blaze, rugosa and rugosa hybrid roses; spirea, beauty bush, sweet pea.

Looking west: Purple and white beardtongues, Rumanian sage, catmint; buds on sea lavender and ladybells.

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

Inside: Aptenia, zonal geranium.

Animal sightings: Woodpecker on utility pole, quail, hummingbird, hummingbird moth on bouncing Bess, grasshoppers, ants, bees, earthworms.

Weather: Hot and windy; last rain 6/5/08; 15:57 hours of daylight today.

Weekly update: Rock roses are what I call a weekend plant. When I leave in the morning, dozens of teardrop buds are nodding along the sides of short stalks rising from foot high plants. When I return, the crinkled petals are gone. I rarely see those petals opened flat to expose yellow stamens to insects in the heat of the day.

Lamb Nurseries convinced me I should try them when they called sunrose "one of the finest evergreen rock plants" that was "excellent on dry banks" and "very hardy." Their last catalog listed 17 varieties in as many shades ranging from orange and apricot through yellow to corals, pinks, and watermelon. When I saw them in a local store, the inch-wide five-petaled flowers recalled moss roses.

The English were much taken with the unpredictable color in the twenty chromosome Helianthemum nummularium. In the 1920's their largest nursery, Norcutt, was introducing stable pinks, primroses, and whites. More hybrids have been produced, partly from crossing the yellow species with other members of the Cistaceae, including the white apenninum and yellow-orange croceum.

It’s taken some years for the cinnamon branches to spread four feet. I bought eight hybrid varieties in 1997, but only a few endured the extremes of both summer and winter. In 1999, I bought more Rose Glory, the one trailing groundcover that had survived. That winter the store’s demonstration planting died while my two lived on.

At the time I assumed I had simply found the sole variety that would grow in this part of the rio arriba. After all, Alan Armitage had found only one variety, Mutabile, would survive the humid climate, clay soils and poor drainage of the Georgia piedmont. Cheryll Greenwood Kinsey continually failed with Henfield Brilliant in Washington before she bought another variety and tried it in a different location.

Since the species thrives on limestone grasslands along the Mediterranean, north to the Baltic and into England, I suspect the problem is less the weather than the species’ adaptation to poor soils. Like many woody plants, rock rose roots attract fungi that provide it with water and minerals in exchange for carbon. These ectomycorrhizal fungi thrive in the upper layers of the soil and are destroyed when the ground is turned over, which of course all good gardeners do. By the time the organisms have recovered the plants are dead.

This is one time my laziness has been rewarded. When I established my beds I already knew the wind was a dangerous foe, so I leveled the land, and added layers of manure, fertilizer, sawdust and mulch. I didn’t spade them in, but added regular soil and heavy sand on top. Now, when I put in new plants I only dig a hole large enough to accommodate the root ball. It’s not the best technique for container grown herbaceous perennials, but it seems to have worked for one cultivar of a woody subshrub.

It actually took less time for the product of sophisticated breeders to become established than it took its species ancestor to recover on abandoned farm fields some twenty miles from the Languedoc coast. There, ecologists found common rock roses reappeared about sixty years after the field was abandoned, and then only after the bunch grasses.

A spreading plant covered with flowers that tolerates poor overgrazed soils and thrives in the south of France where summer droughts are followed by fall monsoons and frequent winter frosts ought to grow here. Too bad it has my work schedule: the Cistaceae blooms when the photosynthesis factory cells are running and rests when the shade returns. Fortunately, it takes no breaks during the month it blooms, so I can see it on my holidays. Then, while I continue my daily commute the rest of the summer, it preens its narrow, dark-green leaves to persist through winter.

Notes:
Armitage, Allan M. Herbaceous Perennial Plants, 1989.

Garnier, Eric, Astrid Bellman, Marie-Laure Navas, Catherine Roumet and Gérard Laurent. "The Leaf-Height-Seed Ecology Strategy Scheme as Applied to Species from a Mediterranean Old-Field Succession," International Conference on Mediterranean Ecosystems, Proceedings, 2004.

Kinsey, Cheryll Greenwood. "Sunrose," available on-line.


Lamb Nurseries catalog, 1996.

Photograph: Rock rose, 21 June 2008.

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