Friday, May 15, 2015

Ramble Report May 14 2015

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.

Today’s route:  Leaving the arbor, we made our way down the path and across the Flower Bridge and through the Oriental gardens, stopping at the Age of Conservation garden, then around the big rock and down the Purple Trail to the Orange Trail.  We turned left on the Orange Trail and made our way up the heath bluff to check on the Mountain Laurel and returned back to the Orange Trail, walking upstream to the bridge to the Flower Garden, which we crossed and took the Orange Trail spur up to the Flower Garden, following the paved path back to the Visitor Center

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:
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.
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.
Cooley's meadow-rue pistillate (female) plant

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.
Spittlebug froth
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.
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.
Stamens unsprung
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.
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.

Common Name
Scientific Name
Virginia spiderwort
Tradescantia virginiana
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
Podophyllum peltatum
Ostraya virginiana
Elliot’s blueberry
Vaccinium elliottii
Family Cercopidae
Northern red oak
Quercus rubra
Sourwood tree
Oxydendrum arboreum
Musclewood tree
Carpinus caroliniana
Silverbell shrub
Halesia Carolina
Brown-headed cowbird
Molothrus ater
Long-leaf summer bluet
Houstonia longifolia
Galax urceolata
Bursting heart
Euonymus americanus
Sweet shrub
Calycanthus floridus
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)
Chrysogonum virginianum
Tulip poplar
Liriodendron tulipifera
Hypoxolon canker
Hypoxylon sp. [atropunctatum?]

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