Sunday, January 16, 2011

Cheese Mallow

What’s happening: To take advantage of early ordering discounts, I have to request plants before I have any idea how many will be dead by spring. Someone was burning his weeds yesterday.

What’s still green: Moss, evergreens, yuccas, Japanese honeysuckle, pyracantha, grape hyacinth, snapdragon, sea pink, cheese, stickseed, gypsum phacelia, blue flax, vinca, snakeweed, broom senecio, strap leaf aster leaves; rose and young chamisa stems.

What’s grey, blue-grey or grey-green: Piñon, four-winged salt bush, snow-in-summer, stickleaf, winterfat, golden hairy aster leaves.

What’s red/turning red: Cholla, beardtongue leaves.

What’s yellow/turning yellow: Globe and weeping willow branches.

What’s blooming inside: Aptenia, Christmas cactus, zonal geranium.

Animal sightings: Animals are staying out of sight.

Weather: The snow has disappeared, leaving plants exposed to dry cold; last snow 12/30/10; 8:47 hours of daylight today.

Weekly update: The low growing, round-leafed cheese mallow can become a great nuisance in lawns, especially those where the grass isn’t yet dense.

Malva neglecta was introduced early into New England, then followed the Yankees west through the Northwest Territory. When it reached the Rockies, the annual spread southwest, moved into the intermontane region, and flourished in the Pacific states, all very different climates.

In this area, the weed appears sporadically, but hasn’t established itself. It’s always having to be reintroduced from somewhere else in the Española valley.

I saw an occasional dark green plant in my garden between 1996 and 2001, but nothing since. They probably came in the tires of the machines that leveled the land for the house and dug septic fields.

The tiny white flowers, with each petal marked by three darkened veins, were present in my neighbor’s yard in 2006 and 2007 where he kept his horses and their hay. Some hairy stems raised a few inches, but not as high as they can grow in more favorable conditions.

Then nothing until Christmas day when I saw two plants where they’d brought in heavy equipment and rocks last summer to stabilize the walls of the near arroyo. I hadn’t seen them the last time I walked that way, ten days before. Between we had our first snow, which put some moisture back into the soil, and daily temperatures that ranged between 10 and the mid-50's.

Indian researchers tested the tough-coated brown seeds in laboratory conditions, and found their ideal germination temperature was in the upper 60's. However, they could sprout when temperatures were as low as 50.

More important, Michigan State scientists found the flat seeds had to first undergo a six-week cold period to germinate. In 2000, Frank Telewski and Jan Zeevaart planted seeds preserved by James Beal in 1879 for a long term test of viability. The only ones that still sprouted were some Verbascum and a cheese.

That one isolated plant was able to reproduce itself. The five-petaled cup encloses ten styles which curl in different directions to fertilize the shorter stamens merged into a single column. In the wild, the nectar attracts various types of bees, small flies and an occasional cabbage butterfly.

It’s assumed the small mallow was introduced and spread accidentally, but it was more valued in the past when the mucilage in the sinewy taproots and leaves was used to improve the efficacy of other medicines. Also, the fact that it’s green in winter made it a valued vegetable, even to Pythagoras and the Greeks.

Last weekend, after the mornings of near zero temperatures, the fluted core leaves were still green and probably edible. However, the outer leaves had died.

When you see something growing out of season, you wonder how. Botanists have focused on the four proteins that control photosynthesis and transfer electrons between themselves. When temperatures drop, so does the rate of electronic energy and with it the demand for the raw materials that feed the process.

The first of the proteins in the chain, the inelegantly named photosytem II, appears to be the key to winter adaption. It utilizes the yellow xanthophyll pigments which absorb light from the center of the light spectrum that chlorophyll can’t process. During the summer, it creates a variant form, zeaxanthin, which rejects light during the heat of the day. In winter, a group at the University of Colorado found zeaxanthin levels remain high on very cold nights, which has the effect of slowing the carbon fixation that feeds photosynthesis and prevents an electron flow overload.

The team also found that Malva neglecta’s return to normal photosynthesis occurred in two phases. One, typical of days during cold spells, returned some normal functions within a few hours. However, the plant’s leaves did not return to normal levels of activity until several days of warm temperatures ensured it was safe to do so.

Unfortunately, I won’t be able to watch the ruffled rosette respond to warmer temperatures this spring. Wednesday they brought back the big-wheels to install a guard rail on one side of the arroyo. The cheeses weren’t there yesterday and neither was the other guard rail.

Notes: For more on the xanthophyll cycle, see the posting on Autumn Leaves for 4 November 2007.

Barbara Demmig-Adams, William W. Adams III,, and Amy S. Verhoeven. "Close Relationship Between the State of the Xanthophyll Cycle Pigments and Photosystem II Efficiency during Recovery from Winter Stress," Physiologia Plantarum 96:567–576:1996.

_____, _____, Volker Ebbert, C. Ryan Zarter, and Todd N. Rosenstiel. "Photosynthesis and Photoprotection during Winter," American Society of Plant Biologists, 2002 meeting.

Hilty, John. "Common Mallow," Illinois Wildflowers website, on insect associations.

Kaur, Charanjeet, S. P. Mehra, and R. K. Bhatia. "Studies on the Biology of New Emerging Broadleaf Weed Malva neglecta Wallr," Indian Journal of Weed Science 40:172-177:2008.

Telewski, Frank W. and Jan A. D. Zeevaart. "The 120-yr Period for Dr. Beal's Seed Viability Experiment," American Journal of Botany 89:1285-1288:2002.

Photograph: Cheese mallow by the near arroyo, 9 January 2011.

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