Abscission

Weather: Despite the occasional snowfall, the exposed ground in my yard is dry as a beach several inches down. The wet soil under the tiles I’m resetting has not frozen.

The house loses heat its retained gradually, so it’s now colder in the house than it was when temperatures were much lower. This week I made the transition from lambs wool sweaters to those made from Shetland wood. Those sweaters are now collecting hair and lint impelled by static electricity activated by the furnace.

Last useful snow: 10/27. Week’s low: 17 degrees F. Week’s high: 654 degrees F in the shade.

What’s still green: Cholla cactus; leaves on privet, juniper and other evergreens, Japanese honeysuckle, yuccas, red hot poker, chives, grape hyacinth, bouncing Bess, pinks, sweet peas, pink evening primroses, golden spur columbine, snapdragons, blue flax, green leaf five eyes, hollyhock, winecup mallow, Queen Anne’s lace, anthemis, yarrow, purple aster, dandelions, June, needle, and cheat grass

What’s still gray or gray-green: Leaves on Apache plume, cliff rose, fernbush, winterfat, snow-in-summer, catmint, Silver King artemisia

What’s still red: Leaves on Bradford pear, woods and pasture roses

What’s turning orange: Tansy

Tasks: I began cutting dead wood in the back roses, and clearing the weeds from underneath them. There was lots of cheat grass stems that came away easily. The new growth is up, and providing some kind of ground protection for the rose roots.

Some sideoats gramma came up along the new soaker hose. I planted seeds elsewhere in 2005, and a few came up in 2015. Two years ago there were plants to the south of the roses. I don’t know if seed from them or native plants landed along the back porch and was just waiting for the right opportunity to sprout.

Animal sightings: Small birds, ants, worms. Insects are coming into garage; I saw two crickets, a moth, and a dying hornet this week.

Weekly update: As I indicated in the post for 1 September 2019 on Duff, the mere work of clearing dead wood and leaves from trees and shrubs is an education in the ways plants protect themselves. It also is a reminder there are no easy generalizations.

When levels of sun light decrease in the fall and the metabolism of plants slows, hormones begin the process of isolating, then dropping leaves. This year’s onslaught of early cold temperatures preempted the process, leaving dead leaves on trees. What happened next has varied.

The apricots, peaches, and some sweet cherries quickly dropped the dead matter, or let the winds remove it. They either had begun the process of abscission, or were able to complete it in the afternoons when temperatures warmed enough to allow some metabolic functions.

The members of the rose family whose leaves had turned red were arrested. The leaves are dead, but still in place. If I touch the ones on the sandcherries, they fall. The leaves on the Bradford pear, however, do not come down. Whatever the interplay of chemicals that produced their fall colors has been reacting differently than the apricots that didn’t have time to change color.

The trees that always hold their leaves still have them. The leaves are still clinging to the cottonwood, and if they fall do so when the wind can blow them away. These are the ones I suspected created problems for the tree’s ability to drink when they accumulated, as they do, on the side where the fence traps them.

The Russian olive also retains its leaves, and the ground is nearly bare under it.

Notes on photographs: Taken 9 November 2019.
1. Bradford pear (Pyrus calleryana) with full set of dead, red leaves.

2. Apricot (Prunus armeniaca) with a few dead, brown leaves; the rest are on the ground under it.

3. Cottonless cottonwood (Populus deltoides) with dead, faded green leaves on the tree, and a few accumulated near the fence. The rest of the fallen leaves have blown away.