Purslane

What’s blooming in the area: Few roses, trumpet creeper, silver lace vine, honeysuckle, canna, datura, silver-leaf nightshade, bindweed, Heavenly Blue morning glory, narrow leaf globemallow, bouncing Bess, white sweet clover, goat’s head, yellow and white evening primrose, toothed spurge, purslane, lamb’s quarter, Russian thistle, pigweed, broom snakeweed, chamisa, winterfat, Tahokia daisy, French marigolds, Maximilian and native sunflowers, áñil del muerto, goldenrod, horseweed, hawkweed, wild lettuce, golden, heath and purple asters; hay cut, apples and peaches beginning to fall.
What’s blooming in my garden, looking north: Golden spur columbine, hartwegii, chocolate flower, blanket flower, coreopsis, Mexican hat, black-eyed Susan, yellow cosmos, chrysanthemum.
Looking east: Hosta, garlic chives, large-leaf soapwort, sweet alyssum, winecup, hollyhock, sidalcea, larkspur, scarlet flax, California poppies, pink bachelor buttons, African marigolds.
Looking south: Rose of Sharon, rugosa rose, Crimson Rambler morning glory, sedum, Sensation cosmos, zinnia.
Looking west: Caryopteris, buddleia, Russian sage, catmint, leadplant, ladybells, purple ice plant, Silver King artemisia, Monch aster.
Bedding plants: Sweet alyssum, snapdragons, petunia, Dahlberg daisy; more Sweet 100 tomatoes daily.
Inside: Aptenia, zonal geranium.
Animal sightings: Quail, hummingbird, gecko, yellow butterfly, miller moth, grasshoppers, ants, bees moved to sunflowers.
Weather: Hurricanes in Caribbean but all I saw was heavier dews and colder mornings; last wet ground September 2..
Weekly update: Even someone as inattentive as I was in high school biology knows there’s something extraordinary about an annual that blooms for only two hours a day, yet perpetuates itself in a clay pot with no visible sign of flying insects.
Purslane is one of those weeds I take for granted. I used to see it everywhere in Michigan, where its red stems spread along the ground in interlacing mats. The succulent leaves were never dense enough for a groundcover, but it didn’t get tall and rangy, didn’t clamor over other plants, and didn’t produce vicious seeds.
John Winthrop, Junior, bought an ounce in 1631 in London before leaving for Massachusetts Bay Colony. Since that’s about 280,000 seeds, he must have intended to grow it for food. No doubt it made the trip many times, sometimes in seed packets like Winthrop’s, other times as a stowaway. Purslane’s now spread to south Pacific islands where there are no familiar animals.
Here in the rio arriba, it displaced the native notch leaved purslane which the Santa Clara once minced to release the mucilage for gravy. By 1915, the old world leaves were eaten by both Tewa and Spanish speaking natives, with no nutritional loss. The newcomer contains vitamins A and omega-3 fatty acids, as well as antioxidants and minerals.
My plant arrived with a potted shrub in 2000. This is the first time I’ve seen the hermaphrodite bloom. It needs light, and apparently didn’t get its necessary eleven hours a day until the sun dropped enough to reach the east end of the porch. In other parts of the country it starts blooming in late spring.
The yellow flowers begin to open around ten in the morning to a maximum width of 5/16". Soon after noon the two sepals begin to close, pushing the five petals closer to the male stamens. Within 25 minutes, the petals fold over the stamens, pushing them towards the female pistil. In another 15 minutes, all the flowers are shut into mitres under the sepals.
When the pollen from the stamens falls onto the stigma, the generative cell produces a pollen tube, which reaches down until it pierces the embryo sac formed in the ovary. Cooper says fertilization is complete within three to four hours of contact. When the seeds are mature, the protective cap breaks away, leaving a tan receptacle bearing black seeds, which spill onto leaves or fall to the ground.
The next day, new flowers open in the base of leaf clusters at the ends of stems. In the afternoons, I can see as many as five buds in an axil, some still buds, some developing grain cups. If the season is long, those seeds may produce the next generation of flowers in four to six weeks. If the winters stay warm, it doesn’t die. If a stem breaks off, it may root itself.
The wind may initiate fertilization, but this flower depends on no such fickle occurrence in its brief fluorescence. Portulaca olearcea may be an old maid, but it is rarely a barren one.
Notes:
Cooper, D. C. "Macrosporogenesis and Embryology of Portulaca oleracea," American Journal of Botany 27:326-330:1940.Robbins, William Wilfred, John Peabody Harrington and Barbara Friere-Marreco. Ethnobotany of the Tewa Indians, 1916.Simopoulos, Artemis P. "Omega-3 Fatty Acids and Antioxidants in Edible Wild Plants," Biological Research 37: 263-277:2004.Winthrop, John Junior. Seed list, included in volume 3 of Winthrop papers held by Massachusetts Historical Society; reprinted by Ann Leighton, Early American Gardens, 1970.
Photograph: Purslane, 2 September 2007.