Moss Rose

What’s blooming in the area: Tea roses, Apache plume, butterfly bush, trumpet creeper, Japanese honeysuckle, silver lace vine, leather leaved globemallow, bird of paradise, alfalfa, white sweet clover, Russian sage, milkweed, velvetweed, scarlet beeblossom, white and yellow evening primroses, datura, Heavenly Blue and bush morning glory, creeping and climbing bindweed, buffalo gourd, goats’ head, purple phlox, cultivated, farmer’s and native sunflower, Hopi tea, goatsbeard, hawkweed, horseweed, wild lettuce, hairy golden aster, Queen Anne’s lace, tahokia daisy, blue and side oats grama grasses.

What’s blooming in my yard, looking north: Hartweg, zucchini, nasturtium, Mexican hat, chocolate flower, coreopsis, blanket flower, black-eyed Susan, chrysanthemum, Parker’s Gold yarrow.

Looking east: Floribunda rose, California and Shirley poppies, hollyhock, winecup, sidalcea, coral bells, bouncing Bess, snapdragons, Jupiter’s beard, coral beardtongue, Maltese cross, pink evening primrose, large-leaved soapwort; buds on garlic chives, cut-leaf coneflower and Maximilian sunflower.

Looking south: Tamarix, Blaze and rugosa roses, rose of Sharon, daylily, bundle flower, sweet pea, zinnia, cosmos.

Looking west: Caryopteris, flax, catmint, lady bells, sea lavender, white spurge, David phlox, perennial four o’clock, purple ice plant, purple coneflower; buds on Mönch aster.

Bedding plants: Moss rose, sweet alyssum, tomato.

Inside: South African aptenia.

Animal sightings: Rabbit, hummingbirds, gecko, bees, hummingbird moths, large black harvester and small dark ants, grasshoppers.

Weather: Storms in the area left rain on Tuesday night, and mediated afternoon temperatures and evaporation levels; last moderate rain 7/22/09; 15:21 hours of daylight today.

Weekly update: Cactus flowers, which were more plentiful this year than usual, resemble Busby Berkeley film musicals. The central attraction is a single pistol, towering above the ensemble like Carmen Miranda in her biggest hat. Surrounding her is a corps of thin stamens, and beyond them a few ladies, the petals, carrying large fans.

Moss roses are so closely related to cacti that they’re thought to be their immediate ancestors. They have the same flower, only everything is a bit more rococo. The single ovary has at least five stigmas which flare and curl. The petals multiply in groups of five. The anthers are sensitive to touch, so when a premier danseur insect moves among them, they bend in its direction. The prima is usually located off center.

Prickly pear flowers in this area are a lemony yellow, much paler than the moss roses blooming in my garden. The magenta of the chollas is a deeper, richer hue than the roses or pinks. All open mid-morning and close before sunset, eschew clouds and water drops.

A friend of William Hooker, probably John Gillies, told him that on the western bank of the Rio Desaguadero, which borders Mendoza province in the rain shadow on the Argentine Andes, there were so many Portulaca grandiflora plants in the late 1820's they "spread a rich purple hue, here and there marked with spots of orange color."

Some twenty years later, in 1851, Joseph Breck offered rose, scarlet, yellow, and white varieties in Boston. He said some white annuals appeared with pink stripes. How the simple color of the natural population could produce the brilliant shades of the cultivated plants, without benefit of any selective breeding, has puzzled botanists ever since.

Before 1921, Seniitiko Ikeno crossed plants he had selected over several generations for pure color. He believed yellow was primary and that the addition of some factor created orange. Further additions spawned red offspring, and even more of some unknown produced the magenta. He also noticed double flowers were dominant over the singles.

Biochemists have now determined both the cactus and portulaca families contain betalain pigments which are created by DOPA (3,4-dihydroxyphenylalanine). When betalamic acid interacts with amino acids it becomes the yellow betaxanthin of the local prickly pear; when it mixes with cyclo-DOPA derivatives it becomes the purple betacyanin of the cholla. Orange results from the presence of both; white has little or no betalain.

Ikeno realized that Portulaca grandiflora did not fit the simple genetic matrix described by Mendel. He believed three factors needed to exist to produce the varieties he observed, an hypothesis Giampiero Franco Trezzini and Jean-Pierre Zÿrd confirmed when they found the biochemical patterns of betalain synthesis were consistent with the existence of three controlling genes.

You have to accept Miranda’s colors to grow moss roses. Most seed companies only offer mixed colors, and most growers put several tiny seeds in each pot. They don’t thin them, both to save labor costs and to make the plants look fuller than they are when they’re sold. No matter what color you see when you buy them in the spring, they will be something else in the summer.

When I bought Sundial F₁ seedlings this spring, they were all apricot. I planted them in an exposed bed where I hoped they would shelter the zinnia seeds. Now both are blooming in gaudy pinks and yellows with the South American natives kneeling in a corps around the taller Mexican pas de quatres, ensembles within an ensemble.

Notes:
John Gillies was a Scotch physician who lived in Mendoza between 1820 and 1828. Hooker, then at Glasgow University, described many of his discoveries according to John Dunne-Brady’s on-line listing of "Eponyms."

Breck, Joseph. The Flower-Garden, 1851, reprinted by OPUS Publications, 1988.

Hooker, William Jackson. Curtis's Botanical Magazine 56:2885:1829, quoted by Zÿrd and Christinet.

Ikeno, Seniitiko. "Studies on the Genetics of Flower-Colours in Portalaca grandiflora," College of Agriculture, Imperial University of Tokyo Journal 8:93-133:1921.

Trezzini, Giampiero Franco and Jean-Pierre Zÿrd. "Portulaca grandiflora: a Model System for the Study of the Biochemistry and Genetics of Betalain Synthesis," Acta Horta 280:581-585:1990.

Zÿrd, Jean-Pierre and Laurent Christinet. "Betalains," Annual Plant Reviews 14:185-213:2004.

Photograph: Moss roses, 19 July 2009, center of apricot flower has several thin stigmas reaching up like posts holding a ring stone between four and five o’clock from the darker stamens.