Twenty three Ramblers turned out today,
including Silvio's parents, one of whom turned out to have been a student in
one of my classes 30+ years ago. We were delighted that they could come and
enjoy a walk in the woods with us!
Hugh contributed today's reading today, an excerpt from John
Burroughs' essay, Nature Near Home:
After long experience I am convinced that the
best place to study nature is at one's home, on the farm, in the mountains, on
the plains, by the sea, no matter where that may be. One has it all about him
then. The seasons bring to his door the great revolving cycle of wild life,
floral and faunal, and he need miss no part of the show.
International
Garden/American South Garden:
The Virginia spiderwort is still blooming. This patch has
flowers of several colors: pink, white, blue and purple. In spite of this
variety they are all the same species. Flower color is determined by a few
genes in most plants. A common pattern of inheritance seen in many plants is
for the white and purple forms to show incomplete dominance when bred together.
The offspring of a cross between white-flowered and purple-flowered plants are
frequently blue-flowered . The pink coloration results from variation in a
different set of genes.
Nestled at the edge of this part of the garden was a mystery
plant that even Hugh couldn't identify with a great degree of certainty. He
thought it might be a "Perfoliate boneset", but changed his mind
later.
Flower Bridge:
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| Bigleaf Magnolia leaves & flower |
On the left side of the bridge is a beautiful sight: a Bigleaf
magnolia in bloom! Not only does this tree have the largest simple leaf of any
North American tree it has what must be the largest flower.
The Bottle brush buckeye we've been watching is still not
blooming. The many inflorescences don't even seem much changed from last week.
On the left side of the walkway, across from the Buckeye are
a lot of variegated Solomon's Seal, long past flowering – just the petioles of
flowers remain on the lower side of the main stem. Variegated cultivars of many
plants seem to be favored by horticulturists (and people who buy plants). The
lighter colored sections of the leaf are composed of cells that are unable to
make the normal amounts of chlorophyll. In effect, the plant has a skin
disease. I guess there is no accounting for taste.
Further along the Korean dogwood on the right side of the
walkway is still in bloom. People often mistake the white bracts for petals. In
reality they are like the white bracts of our native dogwood, modified leaves
that have the appearance of flower petals. So where are the flowers? They are
tightly clustered together in a group and surrounded by the four bracts.
Last week in this area we saw a strange plant that we could
only identify to family – an Arum of some sort. Typical of the Arum family are
two structures, called the spathe and the spadix. You might be familiar with
them from the Jack-in-the-pulpit, which is also an Arum. The spadix is a
structure that bears the flowers and it is surrounded and enclosed by the
spathe. In Jack-in-the-pulpit the "pulpit" is the spathe and the
"jack" is the spadix. Today our mystery Arum was clearly aging as
both spathe and spadix were withered and wilting.
We stopped in the Conservation area of the Garden for two
highlights: the Indian pink (AKA Indian pinkroot) and, in the bog section
below, the pitcher plants.
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| Indian pink |
The red, tubular flowers of Indian pink are characteristic
of hummingbird pollinated plants. Not that hummingbirds won't visit any other
kind of plant (they will), but they seem to find red, tubular flowers
especially attractive.
In the bog below there are numerous tall trumpet pitcher
plants and more inconspicuous small pitcher plants. Several of these had
flowers atop a tall flowering stalk. The pitcher plant flower is very unusual.
Instead of facing upward it is directed downward and the style is greatly
expanded to form a sort of upside-down umbrella. The "spoke-ends" of
this "umbrella" are the stigmas, the part of the pistil that receives
pollen. Pollen drops from the anthers onto the surface of the upside down
umbrella and any bee visiting the flower walks around in this dusty bowl and
collects pollen on its fuzzy surface. When it climbs out of the umbrella it
deposits some of the pollen it carries on the stigmas.
Most of the plants in this section of the garden are either rare,
endangered or restricted to special habitats that are themselves uncommon. One
of the more interesting of these is Cooley's meadow-rue. Like it's relative,
Early meadow-rue, that we saw blooming in the Dunson garden earl this spring, it
is dioecious – each plant bears either exclusively male or female flowers. If
you missed seeing the Early meadow-rue flowers earlier this spring this is your
chance to see some look-alikes.
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| Cooley's meadow-rue pistillate (female) plant |
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| Cooley's meadow-rue staminate (male) plant |
Other uncommon plants in bloom in this special area are a
mint,Hoary skullcap and a legume, False lupine (AKA Hairy bush-pea or Carolina
lupine) and Black cohosh.
George (he of the eagle eye) spotted a tiny spider web in
one of the bushes. This web resembles that of the the Bowl and doily spider,
but lacks the doily; it is made by a Filmy dome spider.
Purple Trail:
At the start of the Purple trail is a small patch of
Mayapples. At least one of them is developing a fruit that is now a little
larger than my thumb. We'll need to keep an eye on this fruit to see when it
ripens. Maybe then the brave among us can sample its taste.
Further down the trail Jackie spotted many frothy spittlebug
"nests." These are produced by the immature stages (called
"nymphs") of a plant sucking insect. The nymphs have mouthparts
specialized for "stabing and sucking." The nymph sucks a steady
stream of plant juices and eliminates a dilute sugary "honeydew" that
it kicks up into a froth. The froth protects it from potential predators. If
you carefully remove the sticky froth you will reveal the nymph hiding beneath.
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| Spittlebug froth |
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| Spittlebug nymph revealed! |
No trip down the Purple trail would be complete without a
stop at the Hophornbeam with sapsucker wells. These are made, not by
spittlebugs, but by a type of woodpecker. The bird excavates a row of small
holes in the tree trunk. Each hole slowly fills with tree sap and is revisited
by the sapsucker for a sugary drink. These sweet holes also attract small
insect that the sapsucker also eats. Eventually the trees seals of the holes
and then the sapsucker has to drill some more. This Hophornbeam has been the
victim of a lot drilling over the years.
Further down the trail we paused to look at the logs of the
Northern red oak that fell last spring. This species can be identified by the
"ski trails" on its bark. (This refers to the flat, light colored
surface of the bark ridges on the tree. In the garden most of the trees with
this type of bark are Northern Red Oaks, but there are also a few Scarlet Oaks
here, so this is not a truly diagnostic feature.)
We also pointed out a Sourwood tree with its very high
ridged bark and curving growth. Honey made from Sourwood nectar does not
crystallize when sitting on the shelf like many other honeys do.
A little further down the trail we found a young Hophornbeam
with a deer rub. The growing antlers of deer are covered with
"velvet", a specialized skin that deposits the minerals that make up
the antler. When the antler is mature the velvet dies and is sloughed off by
rubbing the antler against a tree.
Orange Trail:
Where the Purple trail joins the Orange trail it is flanked
by two closely related trees, a Hophornbeam and a Musclewood. Both trees are in
the Birch family and have almost identical leaves and very dense wood (the
densest of North American trees). They can be easily distinguished by their
bark. The trunk of Musclewood is smooth, gray and looks very
"sinewy", as if there were muscles just beneath. The Hophornbeam, on
the other hand, has brown bark that looks like a cat has repeatedly scratched
it.
Nearby we found a Silverbell, a small tree with striped bark
and leaves with pointed tip, called a "drip-tip" because it promotes
the runoff of water.
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| Unidentified bird egg in nest |
Don pointed out a bird's nest in a small tree overhanging
the bank of the river. It held two brownish eggs, each with darker markings.
We're not sure what bird laid these eggs.
Heath bluff:
We were eager to see if the Mountain Laurel was still in
bloom up on the Heath bluff, so we clambered up the steep, rooty trail and were
soon surrounded by billows of white blooms. Last week Hugh told us about the
way the anthers are held in petal pockets when the flower first opens. When
visited by a bee the disturbance released the anther and the stamen snaps out
of the pocket, sprinkling pollen on the bee. This week Don took these closeups
of unsprung and sprung flowers.
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| Stamens unsprung |
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| Stamens released |
The Galax we saw in last week's ramble were still blooming, as
were the Long leaf summer bluets, but the Rattlesnake weed were largely
finished.
Orange Trail:
Donna found an old oak apple gall that we opened to see the
"starburst" inside. The way the larval feeding tissue is suspended in
the center of the spherical gall always enchants me. No one understands how
such an elaborate structure is induced to form from an oak leaf. It's one of
nature's many mysteries.
It was getting late so we hurried across the Boy Scout
bridge, pointing out the Sensitive fern in the marshy area below the bridge as
well as the Duck potato with its large, arrow-head shaped leaves.
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| Duck Potato |
One of the things we observed last week was Mayapple with
yellow spots on its leaves. One of our ramblers, Bill Sheehan, sent me some information
this week that identified the cause of these spots. They are caused by a
fungus: Mayapple rust. Hugh and I had a disagreement about whether this could
injure the plants. Hugh was right it can be injurious.
Paved Path along
Flower Garden:
Emerging on the paved path we noticed a young tree with
vertically striped bark. I thought at first that it was a Silverbell, because
of the striping, but a glance upward revealed the characteristic leaves of the
Tuliptree (AKA Tulip poplar). Lesson learned: Tree bark often changes in
character as the tree ages. You have to learn bark characteristics at all
stages of development.
The Green and Gold is still blooming at this point in the
garden, but other places where it is present no longer are.
Another
small tree in this area had a number of hard, smooth black spots where the bark
was missing. They look like solidified tar, but are, in fact, a fungal
infection called Hypoxylon canker.
These were first identified for me by Bill Sheehan on an earlier ramble this
year. Click
here to find out more about this disease.
SUMMARY OF OBSERVED SPECIES:
|
Common Name
|
Scientific Name
|
|
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Virginia spiderwort
|
Tradescantia virginiana
|
|
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Bottlebrush buckeye
|
Aesculus parviflora
|
|
|
Big leaf magnolia
|
Magnolia macrophylla
|
|
|
Solomon’s seal cultivar
|
Polygonatum biflorum
|
|
|
Unidentified Arum
|
|
|
|
Korean dogwood
|
Cornus kousa
|
|
|
Meadow Sweet
|
Spirea alba
|
|
|
Dwarf creeping Jenny
|
Lysimachia japonica var.
minutissima
|
|
|
Chinese ground orchid
|
Bletilla striata
|
|
|
Filmy Dome spider
|
Neriene radiata
|
|
|
False lupine
|
Thermopsis villosa
|
|
|
Indian pink
|
Spigelia marilandica
|
|
|
Hoary skullcap
|
Scutellaria incana
|
|
|
Cooley’s meadowrue
|
Thalictrum cooleyi
|
|
|
Black cohosh
|
Actea racemosa
|
|
|
Mayapple
|
Podophyllum peltatum
|
|
|
Hophornbeam
|
Ostraya virginiana
|
|
|
Elliot’s blueberry
|
Vaccinium elliottii
|
|
|
Spittlebug
|
Family Cercopidae
|
|
|
Northern red oak
|
Quercus rubra
|
|
|
Sourwood tree
|
Oxydendrum arboreum
|
|
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Musclewood tree
|
Carpinus caroliniana
|
|
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Silverbell shrub
|
Halesia Carolina
|
|
|
Brown-headed cowbird
|
Molothrus ater
|
|
|
Long-leaf summer bluet
|
Houstonia longifolia
|
|
|
Galax
|
Galax urceolata
|
|
|
Bursting heart
|
Euonymus americanus
|
|
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Sweet shrub
|
Calycanthus floridus
|
|
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Mountain laurel
|
Kalmia latifolia
|
|
|
Rattlesnake weed
|
Hieracium venosum
|
|
|
White oak
|
Quercus alba
|
|
|
Oak apple gall wasp
|
Biorhiza pallida
|
|
|
Sensitive fern
|
Onoclea sensibilis
|
|
|
Duck potato
|
Sagittaria latifolia
|
|
|
Mayapple rust
|
Allodus sp. (rust)
|
|
|
Green-and-gold
|
Chrysogonum virginianum
|
|
|
Tulip poplar
|
Liriodendron tulipifera
|
|
|
Hypoxolon canker
|
Hypoxylon sp. [atropunctatum?]
|
