Friday, November 13, 2015

Ramble Report November 12 2015




Today's report was written by Dale Hoyt. Most of the photos that appear in this blog are taken by Don Hunter; you can see all the photos Don took of today's Ramble here.

Thirty one ramblers met this cool, partly cloudy morning.

Before the reading there were some announcements:

1) Remember 
Next week is the last regular ramble of this year. But, the Thursday following Thanksgiving we will have a special ramble conducted by Wendy Zomlefer, the curator of the UGA Herbarium. That will meet at 8:30AM in the Gardenside Room of the visitor center. There will be donuts, so you might want to skip breakfast.

2) Join the Friends
Learn here about the benefits of becoming a member of the Friends of the State Botanical Garden of Georgia You can become a member at this link. If you're not a member you ought to be. These rambles are made possible by the Garden's programs and facilities and, as a member, you will be supporting the Garden.

3) Why Ginkgo leaves shine golden in the sun
At this time of year the Ginkgo trees near the Arbor have leaves that are a beautiful lemon yellow color in the sunlight. On a cloudy day like today they seem a little drabber, though. There is a reason for this: a chemical compound, 6-Hydroxykynurenic acid. It is produced in the leaves before they drop, captures ultraviolet light and fluoresces it in the yellow wavelengths, increasing color intensity in these leaves. That's why they are so lustrous in sunlight and unremarkable this morning. (The whitening agent in some laundry detergents works on the same principle. It absorbs ultraviolet light and fluoresces its energy in the visible spectrum. Gary mentioned that you could wash your clothes with a whitener and gain some protection from UV light without the expense of buying expensive clothing.)

Today's reading
Emily read a poem, To Each His Own, about falling autumn leaves from Pieces: A Year in Poems & Quilts, by Anna Grossnickle Hines.

Girdled twigs
Girdled oak twig
We then passed out twigs and leaf petioles that we had picked up earlier this week after reading a blog post by David George Haskell. Each of the twigs had been girdled by a twig girdling beetle after it laid it eggs in the twig. Rather than repeating the content of his post I'll just give you a link to it here. (Haskell is the author of the award winning book The Forest Unseen. If you like excellent nature writing you'll love this book.) The petioles were passed around so ramblers could see the difference between a girdled twig and naked petiole. (A girdled twig has buds on one end and a chewed surface around the circumference of the other end. The petiole has no buds and the swollen end is vaguely U-shaped and lacks chew marks.)

Seeds on the sidewalk
Tulip tree seed (top left)
We then started down the cement walkway, looking for the sprouting acorns of white oak. The recent rains have resulted in ideal conditions for oak germination and we found many acorns on the edges of the sidewalk with tiny roots peeking out from the end of the nut. If you want to grow an oak just place the acorn in firm contact with the soil, rootlet pointing down. If you have squirrels don't expect to get a tree – you'll need to protect the acorn or start it in a spot, like a pot, that squirrels can't reach.

Also seen on the sidewalk are the seeds of the tulip tree. They resemble tiny canoes without sides. The curved, lumpy end hides the seed. The long, flat part catches the wind and allows the seed to be carried some distance from its parent plant.

White ash & Witch hazel
Further down the walk there is a white ash on the right. This may be the only white ash in
Witch hazel flowers
the garden; most of the ashes in the natural areas are green ashes (we visited one at the end of the ramble.) Just beyond the white ash, on the right, are the two American witch hazel shrubs we have been watching all year. They have finally begun to bloom, but the flowers are tiny this year, about the size of a dime. Why would a plant produce flowers this time of year, in a season where cold weather prevents many potential pollinators from flying? Some have suggested that the witch hazel escapes competition for pollinators by blooming at a time when there are no other flowering plants in bloom. But that leaves only the insects that can be active in cold weather to perform pollination. Fortunately there are some moths, winter moths, that are capable of flying when the temperature is low. These are the likely agents that transfer pollen between the witch hazels.

Mockernut hickory, Dogwood, Sourwood
We entered the Dunson Native Flora Garden and stopped to look at the diamond-furrowed
Dogwood bark up close
bark of the mockernut hickory. On the path to the small bridge we suggested that people look for more girdled twigs since we had found some earlier. By the bridge are two trees, a dogwood and a young sourwood. The dogwood has dark, checkered bark that is very distinctive. It is broken into small, squarish blocks that are easily recognized. The sourwood is young and has not yet developed the deeply furrowed bark that is typical of more mature specimens. We searched for fallen leaves and managed to locate a few that were still tinged with pinkish red and had the typical sourwood shape. Sourwood is one of the first trees to change color in the fall and most of its leaves have been on the ground long enough to have completely lost their color. The other characteristic of sourwood is its growth pattern – it tends to "wiggle" around, looking for light, so that you hardly never find one that grows straight up. They all have twisting, leaning trunks.

Magnolia buds
Ashe magnolia bud
At the next bend there are two Ashe's magnolia trees. Most of the leaves are gone, but the very large terminal buds are visible. These are characteristic of magnolias and can help you identify them even when the leaves are absent.

Sensitive fern
Next to the magnolias are a large group of sensitive ferns with many fertile fronds. In this species the spore-bearing pinules are held tightly against the stalk and the pinnules (fern-speak for leaflets) emerge opposite of each other. This contrasts with the netted chain ferns that we saw later.

Sharp-lobed hepatica
Sharp-lobed hepatica
Along this section of the path are newly emerged leaves of sharp-lobed hepatica. These will last over winter and give the hepatica a jump over the other spring ephemeral species. It is usually the earliest of our spring flowers to bloom. Hugh once found a closely related species, Anemone americana, blooming in the Garden during the first week of January!

Sycamore
Growing next to the bridge are two young sycamores with their
Sycamore bark
multicolored, camouflage-like smooth bark. The bark flakes off in large pieces and someone asked me if there was a reason why that happens. Someone I knew once told me that they thought it was to discourage vines from climbing up the trunk. Sure enough, we found an another, older sycamore elsewhere that had a vine climbing on it. But the vine was losing its grip because the bark had separated from the trunk. That older sycamore also exhibited a change in the bark – in older trees the bark at the base of the trunk becomes dark and ridged, looking more like conventional tree bark.

Leaf miners on Golden ragwort
Golden ragwort leaf mine
One of the other early spring bloomer is golden ragwort and it has a winter rosette of green leaves that are well developed now. Also interesting is that these leaves are supporting a population of leaf miners – insect larvae that feed inside the leaf, between the upper and lower epidermis. After an egg is laid on the leaf the larva burrows in and begins to crawl through the leaf, feeding as it moves. The path of its movement grows in width as the larva grows in size until it is ready to pupate. Some kinds then leave the leaf and pupate in the leaf litter below but others actually pupate in the leaf itself. Leaf miners are usually tiny flies or moths and are poorly known. There are many hundreds, probably thousands, of undiscovered species. They are tiny, difficult to study and rear and not very many people are interested in them. But they are fascinating in the way they wander, seemingly at random, in their restricted green universe.

Little brown jugs
The other plant producing fresh foliage for the winter is little brown jugs. The common name refers to the flowers that develop buried in the leaf litter below the leaves. They look like small, earthen jugs, hence the common name. We'll find them around the middle of spring.

Cranefly orchid
Cranefly orchid leaves
All along the path in this part of the garden we noticed the leaves of the crane fly orchid. It's unfortunate that they have picked a place where they can be stepped on easily, so keep your eye out for them as you walk through the garden.

Netted chain fern
We finally reached a small group of netted chain fern, the one that is easily confused with the sensitive fern. One specimen had a fresh fertile frond and we saw that the spore-bearing branches were held away from the stem, almost at right angles. Also, the pinnules of the sterile fronds alternate along the length of the frond.

Mystery caterpillar
Mystery caterpillar
Across from the netted chain fern is a large bed of marsh fern. Mary Ann told us that it is rhizomatous, rather than clumping, which means that after it is established in can spread far and wide, just as this clump has. There was also a surprise present. Many of the fronds had been eaten, which is not something that you see happen to ferns very often. And then a sharp-eyed person found a caterpillar sitting conspicuously on a partially eaten frond. The reason ferns are not often eaten is that their tissue contains large amounts of substances that are toxic to herbivores. But this caterpillar seems to have found a way to evade that defense. Carmen, the Sandy Creek Nature Center naturalist and our goto person.when we find an insect we can't identify, tells us that this caterpillar is a species in the genus Haploa, a group of moths commonly know as Tiger moths.

Basswood & Linnaeus
Lower in the garden is a large Basswood (Tilia americana) that has lost all its leaves. To identify it you need to carry a large stick give the trunk a whack. If you hear a hollow resonance you've hit a basswood. They often develop a heart rot that makes them hollow. When the tree is injured animals use the interior as a place to shelter or build a nest. Raccoons often nest in hollow basswoods.

In Europe the basswood is known as the Linden (a different species in the same genus as our American basswood) and here is the connection to Linnaeus. (Linnaeus is credited as the founder of our modern system of scientific classification and the way of naming living organism (the binomial name, genus + species epithet; e.g., Homo sapiens). Linnaeus' father was a named Nils and to attend the university he had to have a permanent surname. At the time Swedish boys were known simply as their father's sons; Nils would be known as Bengtsson and Nils sons as Nilsson. There was a large Linden growing on or near their property so Nils latinized the Swedish name for the Linden, Lind, and his surname became Linnaeus. Nils son Carl became Carl Linnaeus or, fully in Latin, Carolus Linnaeus.

Juniper
Juniper berries
We left the Dunson garden and walked down the access road toward the Lanier center to look at two trees, an Eastern red cedar and a Green ash. The common name for the Eastern red cedar is misleading, because it is not a true cedar. The Eastern red cedar is a Juniper (Juniperus virginiana) and true cedars are in the genus Cedrus. But names aside, we stopped to look at the tiny blue "berries" of the juniper. These are actually highly modified cones. The scales of the cone are fleshy and fused together, creating what looks like a berry but is developmentally quite different.

Green ash
Green ash seeds
Growing near the Juniper is a Green ash with a large broken limb bearing thousands of fruits. This is bad for the tree but good for us
Green ash leaf scar and bud
because it allowed us to easily look at one of the features that allows us to identify the tree. The ash fruit has a long wing and the seed is found at one end, completely enclosed by the wing. In a White ash the wing of the fruit does not completely enclose the seed. Additionally, the buds are located on top of the leaf petiole in the Green ash and they are partially surrounded by the petiole base in the White ash. This is most clearly seen on naked twigs by looking the scars left after the leaves have fallen. In the Green ash the leaf scar is a semicircle with the bud sitting on top of the flat side. The leaf scar of the White ash is more U-shaped with the bud nestled in the depression.

Silverbells
Silverbell bark
Emily reminded me that I had forgotten to look at the Silverbell tree in the Dunson garden so we returned. Silverbells produce beautiful
Silverbell fruits
small white flowers in the spring that hang down, looking like hundreds of silver bells glistening in the sunlight, hence the common name. The young tree has a characteristic striped bark. We also found some dried seed pods remaining on one of the trees. These have four thin ridges that surround the pod.

Filbert catkins
Filbert catkins
On the way back to the arbor we noticed that the American filbert bush had catkins. Catkin is the name applied to the male inflorescence in the birch family. It is a long cluster of staminate flowers (Staminate flowers can't make seeds; they have only stamens, the pollen producing structures of flowering plants.) Catkins are typical of the birch family, but plants in other families, like oaks, have similar clusters of flowers. These on the filbert will not open until spring.

Then it was time to return to the arbor and for some of us to enjoy beverage and conversations at Donderos'.

SUMMARY OF OBSERVED SPECIES:
Ginkgo tree
Ginkgo biloba
White oak
Quercus alba
Tulip poplar
Liriodendron tulipifera
Flowering dogwood
Cornus florida
Sourwood
Oxydendrum arboreum
Ashe’s magnolia
Magnolia ashei
Sharp lobed hepatica
Anemone acutiloba
American sycamore
Platanus occidentalis
Golden ragwort
Packera aurea
Little brown jugs
Hexastylis arifolia
Jack in the pulpit
Arisaema triphyllum
Cranefly orchid
Tipularia discolor
Netted chain fern
Woodwardia areolata
Tiger moth caterpillar
Haploa sp.
Marsh fern
Thelypteris palustris
Basswood tree
Tilia americana
Silver bell tree
Halesia carolina
Eastern bluebird
Sialia sialis
Juniper/Red Cedar
Juniperus virginiana
Green ash
Fraxinus pennsylvanica
Georgia mint
Clinopodium georgianum
Ogeechee tupelo
Nyssa ogeche
American  witch hazel
Hamamelis virginiana
Japanese witch hazel
Hamamelis japonica
American filbert
Corylus americana
White ash
Fraxinus americana
White oak
Quercus alba
Slug
Mollusca: Gastropoda
Whitetail deer
Odocoileus virginianus
Mountain mint
Pycnanthemum incanum
British soldier lichen
Cladonia cristatella
American beech
Fagus grandifolia


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