Of sweet vegetables, flattened foliage, and purple leaves

Vegetables grown in these conditions were remarkably sweet, grew quite low to the ground, and developed purple foliage.

We’ve reported earlier on three qualities we observed in our vegetables this winter: the supernatural sweetness of flavor, the propensity of the foliage to flatten to the ground, and a purplish cast on much of the foliage.

We found more information on these phenomena in two different books entitled Botany for Gardeners.

The first Botany for Gardeners (Timber Press), by Brian Capon, implies that the sweetness is nature’s way of protecting the plants from the cold:

“Leaf cells are prevented from freezing by the presence of high sugar concentrations acting as ‘antifreeze’ in the protoplasm. Dissolved sugars and other cellular substances depress the freezing point of water, as do solutions of specially prepared chemicals sold to protect automobile cooling systems in winter. Plants have been ahead of human intervention by several million years.”

Essentially, as Capon describes it, we have been enjoying nature’s antifreeze this winter.

In a chapter entitled “Protection in extreme environments,” Capon discusses adaptations made by alpine wildflowers that seemed to apply to our crops, especially their propensity to grow low to the ground:

“Another advantage to low growth is that leaves and flowers are positioned close to the ground, in a shallow layer of air warmed when the sun’s heat is reflected from the soil. In temperatures a few degrees higher than ambient air, the development of low-growing plants is favored. . . .”

As for the purple cast to the leaves, we found a possible explanation in a different, older Botany for Gardeners (Macmillan, out of print), by Harold Rickett.

Rickett writes that leaves contain two kinds of chlorphyl, which make them green, and xanthophyll and carotene, which turn certain plants autumnal colors when photosynthesis stops in the autumn. But what about that reddish purple? Here’s what Rickett says about one of chlorophyl’s properties:

These carrots display the purply foliage; you can also see how the leaves tried to grow parallel to the ground rather than vertically to the sun.

“The green material [chlorophyl] has a curious property known as fluorescence; which means that it has two different colors in its different aspects. If you hold it up to the light and look at the light which comes through it, the transmitted light, it is green; but if you place it in a strong beam of light and look at its surface, some of the light reflected from it is a rich wine-red.”

We’re theorizing that because our plants are growing under two layers of shade–the greenhouse itself and the fabric row covers we employ on the coldest days and nights–the wine-red that Rickett refers to is asserting itself in our plants. It has no effect on their flavor and is a rather attractive addition to salads and side dishes.

We would welcome further explanations from botanists of horticulturalists.

Meanwhile, the collards and kale are putting out new growth, and we have planted seeds in some of the beds we cleared a few weeks ago. And March came in like a lamb. . . .