Sunday, May 03, 2015

Bean Origins

Weather: Rain yesterday.

What’s blooming in the area: Spirea, bearded iris, moss phlox, donkey spurge.

Beyond the walls and fences: Alfilerillo, western stickseed, purple and tansy mustards, hoary cress, oxalis, common and local dandelions.

In my yard: Tulips, grape hyacinth, vinca.

Bedding plants: Snapdragon, pansy.

What’s blooming inside: Zonal geraniums.

Animal sightings: Small birds, ants.

Weekly update: Beans are a new world plant met in different forms by explorers. The English saw navy beans, the Spanish found pintos and limas. Linnaeus saw them as extensions of existing European species and grouped many into Phaseolus vulgaris and some in Phaseolus lunatus. When Asian beans were encountered, they were placed into the most likely category.

Some of the chaos has been cleared. Bernard Verdcourt has removed varieties like mung and adzuki beans into their own genus, Vigna. They need less sun than the long day or neutral American types.

Explorers then were searching for domesticated plants like coffee and tea which would bring wealth to their sponsors. Today, plant hunters are collecting wild plants hoping to find another aspirin or penicillin.

Paul Gept and others have analyzed one of the proteins common to Phaseolus vulgaris, phaseolin. They found two major strains in cultivated forms, the S found in México, and the T from the Andes. More variety existed in the wilder specimens from México.

The botanists noted beans from México "tend to flower later and for a longer time, have longer racemes peduncles, more floral nodes per raceme, larger flower bracteoles, and smaller seeds than those from the Andes." Also, the S and T cannot produce fertile offspring.

They expanded their tests with newly collected varieties from Columbia and the Andes. With more information, it seemed possible Phaseolus vulgaris was also domesticated in the coastal region, because it had S, T, and other protein types.

Taken together, Gepts concluded there’s "evidence for multiple, independent domestications of the common bean in Middle America and the Andes." Jonathan Sauer has gone farther, suggesting they probably already were different species. However, he conceded, it’s probably too late to sort it out. All those collections have been organized according to Linnaeus.

No one yet has found much evidence for the stages of domestication. There’s only two obvious differences, both of which may be attributed to human selection. Domestic beans are larger than wild ones and their pods do not explode. It’s fairly obvious, unscattered seeds were more likely to be collected than ones camouflaged by ground debris.

The most important domestication stage isn’t obvious from the plants. It was learning how to cook and eat them. Once alkaline chemicals were added to corn, it became a nutritious food. When people in the deep south and in Italy took corn into their diets without the preparatory step they suffered from pellagra.

Many beans contain toxic levels of Phaseolunatum. The legume form of prussic acid is released in damp conditions, and appears in the highest concentrations "in small, plump, solid-colored or spotted seeds of wild tropical varieties," according to Oscar and Ethel Allen. It can be removed by boiling.

Natives not only learned about boiling, but they also may have figured out the lighter colored seeds were less likely to cause problems. They no doubt began to collect ones they remembered were safer to eat. When Americans generalized from their view that raw, whole wild foods are always better than cooked white ones, they got sick.

Notes: Aspirin is acetylsalicylic acid originally derived from the willow; penicillin was first derived from the Penicillium chrysogenum bacteria.

Allen, O. N. and Ethel K. The Leguminosae, 1981.

Gepts, P. and F. A. Bliss. "Phaseolin Variability among Wild and Cultivated Common Beans (Phaseolus vulgaris) from Colombia," Economic Botany 40:469-478:1986; second quotation, "Middle America" includes México.

_____, _____, T. C. Osborn, and K. Rashka,. "Phaseolin-Protein Variability in Wild Forms and Landraces of the Common Bean (Phaseolus vulgaris): Evidence for Multiple Centers of Domestication," Economic Botany 40:451-468:1986; first quotation.

Sauer, Jonathan D. Historical Geography of Crop Plants, 1993.

Photographs: Trees are continuing on their predetermined courses after the frost of 17 April. All photographs taken yesterday, 2 May 2015.

1. Catalpa releafing.
2. Apricot fruit dying away.
3. Elberta peach flowers drying, then falling.
4. Black locust releafing.
5. Bing cherry flower remains hidden by leaves.

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