NATURE’S TURN: Marcescent trees, frost-hardy vegetables

Usually, leeks and the cabbage family survive uncovered until the end of November and beyond. Parsnips left in the ground through winter are prized as a spring treat after the ground thaws.

November 9 –22, 2015

Red oaks color the November hills russet. Beech add areas of burnt sienna. A line of poplars create a streak of bright yellow and, far away, a single crown stands out, a round golden blaze in the hills gone brown. Beech and oak leaves, among others, cling to their twigs long after the leaves of most deciduous trees have detached. How they rattle in the breeze and reflect sunlight like mirrors!

Can anyone guess what this swathe of pink is? Photo: Judy Isacoff
Can anyone guess what this swathe of pink is? Photo: Judy Isacoff

Time and strong winds are sending many of these fanciful, leathery cutouts flying and floating to earth. Those that remain on the trees through winter are usually on the lower branches of mature trees and on young specimens. Beech leaves weather to a delicate texture and softly faded color by winter’s end. It is postulated that marcescent trees, those whose leaves cling to their stems beyond autumn, are a category between evergreen and deciduous.

The process that brings about leaf drop is succinctly explained by Nancy Rose of the University of Minnesota, “In autumn, the leaves of most deciduous trees develop an abscission layer where the petiole (leaf stalk) meets the branch. This allows the leaves to fall off without leaving an open wound on the stem. Dry leaves stay on marcescent trees because the leaves didn’t develop the normal abscission layer in autumn.”

Leeks that have withstood 20 degree nights. Recommend digging before the ground freezes. Photo by Judy Isacoff
Leeks that have withstood 20 degree nights. Recommend digging before the ground freezes. Photo by Judy Isacoff

Abscission is from the Latin ab, meaning away, and scindere, meaning to cut. The abscission layer makes possible the natural detachment of dead leaves as well as ripe fruit in plants and shedding in animals. From Wikipedia, “In trees, an abscission zone, also called a separation zone, is formed at the base of the petiole. It is composed of a top layer that has cells with weak walls, and a bottom layer that expands in the autumn, breaking the weak walls of the cells in the top layer. This allows the leaf to be shed.”

In the mostly denuded understory, forest edge and garden, blueberry shrubs excite the eye with a full quotient of soft pink leaves, or a thinning head of yellow and green. Witch hazel blossoms persist, but are losing vibrancy.

In the vegetable garden, frost-hardy stalwarts like parsnips, collards, kale, leeks, carrots, lettuce, parsley and other herbs feed us well into November, despite a few nights in the 20’s. On the most frigid nights, a light cloth cover, whether fabric available at garden centers or bed sheets, can keep foliage from freezing. Usually, leeks and the cabbage family survive uncovered until the end of November and beyond. Parsnips left in the ground through winter are prized as a spring treat after the ground thaws.

A 5 gallon plastic barrel with alternate layers of quarry sand and root vegetables. The top layer of vegetables will be covered with sand. Photo by Judy Isacoff, October 26, 2015
A 5 gallon plastic barrel with alternate layers of quarry sand and root vegetables. The top layer of vegetables will be covered with sand. Photo by Judy Isacoff, October 26, 2015

We, like all creatures who feel winter’s approach, are responding to the strong urge to harvest crops and prepare them for safekeeping. Whenever time allows, I strip kale leaves from their stems, shred them with the food processor’s cutting blade, briefly steam or stir-fry and then pack into zip-lock bags and freeze. Bunches of parsley are fed down the food processor’s tube to be caught in the chopping blade and chopped very fine before the possible addition of garlic, sunflower seeds or other oily seeds or nuts. Olive oil is streamed in at the end to form the consistency of a paste. This pesto-like, nourishing green concentrate can be spooned into zip-lock snack packs to create logs that, when frozen, may be cut to the desired size with a serrated edge knife and added to most dishes. When freezing, it is best to put the pesto that is in thin plastic bags, i.e. snack packs, into another bag for added protection.

Landscape maintenance and enhancement continue as long as mild weather encourages the effort. Cut down standing dead stalks, remove weeds and rake leaves away from garden and house where rodents could take up residence. Bulbs may still be planted and, along with all recent perennial transplants, water well before the ground freezes.

Resources:

https://en.wikipedia.org/wiki/Abscission

https://www.nofamass.org/content/workshop-descriptions

https://viettes.wordpress.com/tag/why-do-beech-trees-hold-leaves-through-winter