Ramble Report November 15 2018

Today's Ramble was led by Linda Chafin.

Here'sthe link to Don's Facebook album for today's Ramble. (All the photos in this post are compliments of Don.)

Today's post was written by Linda Chafin.

Ramble Report November 15, 2018

Today’s leader: Linda

Today's emphasis:  Seeking what we find and getting back by 10.

7 Ramblers today.

Today’s Reading: Jeff read “Tapestry,” by Phyllis Barnet, a commemoration on a plaque at the Bryant Ridge Appalachian Trail Shelter in Virginia.

Autumn threads it slow burn
through the forest loom

we spin into winter and my
twenty forth year

the 1^st without you brother,

your last fall fringed in loose hung stings
I braid them now, twist to

yarn the quiet fire that brought
you back to dust

This shuttle beats the rhythm of
your heart, I'll lay the half-done
cloth for the wind to weave over
mountains season after season
after season

Show and Tell: Dale brought White Oak acorns gathered two weeks ago to see how many were occupied by weevil larvae. Over the course of two weeks six weevil larvae chewed their way out of their host acorn. One large acorn had germinated even though it had 4 exit holes, indicating that 4 weevil larvae had been eating its food stores. All told, six weevil grubs emerged from 15 acorns.

Today's Route:   We walked through the Great Room and out back through the International Garden, took the Purple Trail to the river and returned to the Visitor Center in time to meet the other ramblers for refreshments and conversation at the Cafe Botanica.

LIST OF OBSERVATIONS:

Plaza Fountain:

Dorotha asked about all the fresh new pitchers on the pitcher plants in the plaza fountain. Most of these pitcher plants are hybrids between the White-topped Pitcher plant and another species of pitcher plants, as can be seen by the white mottling and ruffled edges at the top of many of the pitchers. White-tops are famous for their twice-yearly pitcher flushes – one in spring, the other in fall, with the latter being especially vigorous. The plants in the fountain seem to have inherited the fall-flushing gene from their White-top ancestor.

Herb and Physic Garden:

American Witch Hazel; even without the rain drops the petals are scraggly.

Witch Hazel is currently blooming, one of only two native flowering plants that bloom at this time of year. Actually they started blooming several weeks ago, in late October. Whenever autumn days are warm and sunny enough for insects to fly you can find them on the Witch Hazel flowers. Further north, with a cooler climate, naturalist Bernd Heinrich suggest that a group of moths, called, appropriately, Winter Moths, might be their pollinators. Winter moths can fly when the air temperature is close to freezing.

And what, you ask, is other native flowering plant that blooms as late or even later than Witch Hazel? Mistletoe!

Ginkgo leaves in their fall color.

Linda pointed out the golden colors of the Ginkgo tree and the Pawpaw patch. Dale reminded us that the yellow color in autumn leaves is due to the presence of a group of pigments called carotenoids. These pigments are present in the leaf throughout the growing season, but are masked by chlorophyll. When the chlorophyll degrades in the fall (a process triggered by longer, cooler nights), the yellow color shines through. Yellowing of leaves any time of the year due to disease or herbivory results from the same process: the breakdown of chlorophyll.
Many people notice the brilliance of the yellow Ginkgo leaves. This startling color is not solely due to carotenoids. An additional chemical, 6-Hydroxykynurenic acid (6-HKA), is present in the leaves and reaches its highest concentration just before they fall. 6-KHA has an unusual property that explains why the yellow color of the leaf is so intense: it absorbs ultraviolet light, which is invisible to the human eye, and re-radiates it in the yellow part of the visible light spectrum. This phenomenon is known as flourescence. The same principle is used by fabric whiteners but the whiteners re-radiate a broader spectrum of light, which we perceive as white.

The red color in fall leaves has a different origin. As nights lengthen and cool, a waxy layer forms at the base of the leaf stalk of trees such as maples, sourwood, sweet gum, and black gum, sealing the leaf off from the plant’s vascular system. Sugars that are produced in the leaf on warm autumn days are trapped in the leaf by the waxy layer and are converted to a group of pigments called anthocyanins. Anthocyanins include the pigments responsible for nearly all red and purple coloration in plants, including red and pink flower petals; the outer surface of apples, cranberries, and blueberries; and the lower surface of Crane-fly Orchid leaves, just to name a few. (An exception are beets, colored by a non-anthocyanin pigment called betalain.)

One reason that southern autumns are usually not as colorful as those in the northeast is that our forests are dominated by hickories and some oak species whose leaves do not produce anthocyanins. Northern forests are more likely to include sugar maples, whose leaves do. Also, we in the Piedmont rarely get that lucky combination of warm days and cold nights that produce the brightest colors– a good excuse for a trip to the Blue Ridge!

Purple Trail:

Water Oak acorn; from the bottom.

Partially eaten Water Oak acorn; from the top.

Numerous Water Oak acorns were seen scattered along the leaf-covered path on the Purple Trail. Many were half-eaten, probably by squirrels or chipmunks, and were highly visible due to the orange color of the exposed meat of the acorn. That coloration might be due to the presence of tannins. Water Oaks are members of the red oak subgroup and have higher tannin concentrations than white oaks. Tannins are astringent and, in high concentration, make food almost inedible. Unripe persimmons are an example you may be familiar with. Red wines also get their “bite” from tannins in the grape skins. (White wines, which lack the bite, are made from grapes minus their skins.) But tannins have another effect: they inhibit the growth of fungi that would like nothing better than to feed on acorns and other fruits. The partially eaten acorns might result from naïve rodents discovering what is edible and what is not.

Hornbeam Disk mushrooms

There is a bumper crop of Hornbeam Disk mushrooms on the Hophornbeam trees this fall.  Despite recent heavy rains, the disks appeared to have desiccated a bit, becoming more like shallow, white-rimmed cups.

Sweet Gum leaves, one a deeply lobed sun leaf and the other a less lobed, more typical star-shaped leaf from lower down on the tree, where increased leaf surface maximizes photosynthesis in the filtered light.

A wet and shiny False Turkey Tail mushroom, with green stripes of algae growth alternating with unaffected red stripes.

A large, wet and shiny red-orange wood ear mushroom was seen on one of Northern Red Oaks we visited last week.

Coral-pink Merulius fungi growing on the downed Northern Red Oaks that we saw last week.  As usual, they seemed to be growing with False Turkey Tails.

Brilliant white examples of Little Nest Polypore

Lion's Mane

Don spotted two small Lion's Mane fungi on the underside of a fallen log. Lion’s Mane is widely collected as a choice edible mushroom. Our examples are still very small–Lion’s Mane can reach more than a foot in width.

SUMMARY OF OBSERVED SPECIES:

Ginkgo	Ginkgo biloba
Witch Hazel	Hamamelis virginiana
Pawpaw	Asimina triloba
Water Oak	Quercus nigra
Hop Hornbeam	Ostrya virginiana
Hornbeam Disk Mushroom	Aleurodiscus oakseii
Winged Elm	Ulmus alata
Sweet Gum	Liquidambar styraciflua
Northern Red Oak	Quercus rubra
False Turkey Tail	Stereum ostrea
Wood Ear	Auricularia sp.
Coral-pink Merulius	Phlebia incarnata
Little Nest Polypore	Trametes conchifer syn. Poronidulus conchifer
Lion's Mane	Hericium sp.