Sunday, March 5, 2017

Ramble Report March 2 2017

Today's report was jointly written by Don Hunter and Linda Chafin with additions by Dale Hoyt. Don's album of photos from today's ramble can be found here.

33 Ramblers today.

Today's readings: Bob Ambrose recited one of his new creations: Reverie - Afternoon in the Botanical Garden and Marguerite read Howard Nemerov's Trees.
Today's route: We began with an observation of the Ginkgo trees at the Shade Garden arbor then walked down the Shade Garden walkway to the Dunson Native Flora Garden. We walked through the Dunson Garden to the head of the wetlands display and returned the same way back to the Shade Garden arbor, and, for many, on to the Visitor Center to the Cafe Botanica for socializing over food and drink.
Gingko short shoots and pollen cones
Ginkgo trees at the Shade Garden Arbor.

Ginkgo trees have a geological presence stretching back 270 million years. They are usually regarded as Gymnosperms very distantly related to pine trees or cycads and their relatives. Unlike angiosperms, their seeds are not enclosed by an ovary wall. Each tree is either male or female; the male plants produce cones that look something like a cross between a miniature pine cone and an oak catkin. Female plants are undesirable because their "fruit" smells horribly when stepped on. (The "fruit" is not a true fruit; it is a seed surrounded by a soft, fleshy tissue and a hard tissue.) Occasionally an otherwise male plant develops a branch that produces fruit, but this is very rare.
The pollen produced by the male cones is potentially allergenic, but Gingkos are seldom planted in sufficient numbers to be a significant source of hay fever.
The long branches bear numerous short shoots along their length. Each short shoot starts life as a lateral bud that fails to elongate. Each year a new bud forms at the end of the shoot, so it continues to elongate over time. Since the growth is minimal the shoot is composed of has a series of little ridges along its length, each ridge indicating a year’s miniscule growth. The “long shoots” continue to grow and lengthen a normal amount. Some of our native trees, such as birches and hollies, also produce short shoots. These stubby structures typically bear a cluster of leaves and flowers at their tips. One theory about the adaptive value of short shoots is that the flowers and fruits are held extra close to the source of their energy–the leaf cluster. Also short shoots allow for additional spacing of leaves within the tree’s crown, perhaps exposing more leaves to the sun’s rays. Interestingly, short shoots may change into long shoots after a few years.

Red maples with different color seeds

Red maple developing winged seeds (samaras).
Note that the red color is fading from the wings.
Red Maples at the lower parking lot.
At the end of the central island in the lower parking lot are a group of Red Maple trees. One tree displays red flower parts at the ends of its branches, another, much taller, tree bears light tan-colored parts on its branch ends and a third tree is devoid of any ornamentation. Our initial thought was that we were seeing something like genetic variation in the coloration. Most Red Maples produce red flowers but a few lack the intense red and have flowers that are light orange or yellow in color. But after watching the red maples in my neighborhood I have a different explanation. The trees are genetically variable, but in development, not flower color. Not all the maples flower at the same time, but when they do their floral parts are a deep crimson. As the seeds develop the ovary enlarges and transforms into the familiar "helicopter seed" (the actual seed is a swelling at one end of the wing). This increase in size is accompanied by a decrease in redness, almost as if the red pigment was being diluted. Finally, the mature fruit becomes tan in color and is released from the tree and flutters to the ground.
My conclusion is that the tree with tan colored branch tips began to flower earlier than the tree with red branch tips. We are looking at genetic variation in flowering time, not color. We can tell is this idea is correct by carefully observing these same trees next year.
Shade Garden
Buckeye leaves emerging from bud

Buckeye leaves expanding
Bottlebrush Buckeye terminal leaf buds are opening now. This species blooms much later in the year and spreads clonally, as seen by the many stems nearby.
Haxelnut male catkins

Hazelnut female flowers
The red structures are the stigmas that receive pollen.
American hazelnuts (filbert) are blooming now, with the conspicuous tan catkins (that hold male flowers) hanging from the slender limbs and twigs. We also saw the not-so-obvious female flowers, with their tiny, minuscule explosions of fine, deep pink to red thread-like stigmas. The dangling, flexible catkins indicate that hazelnut, like other catkin-bearing plants (e.g. oaks, birches), are wind-pollinated. Though no one in the group has ever eaten them, American hazelnuts are said to be quite tasty.
Aucuba flowers
Japanese Aucuba
On our way back to the arbor several Ramblers stopped with Linda to look at a large flowering shrub, the Japanese Aucuba.  The four-petaled flower has a startling resemblance to the flower of the purple bedstraw plant. These two plants are not in the same families, but botanists consider the two families closely related (bedstraw is in the Rubiaceae family and Aucuba in the Garryaceae family.)

Dunson Native Flora Garden
Chattahoochee trillium

Not long after entering the Dunson Garden, we began to notice many of the long-stalked Chattahoochee trilliums, most with tight, upright buds but some with fully open flowers. Linda recounted the life history of trilliums. The seeds take 1 to 2 years to germinate and then produce a single leaf. In successive years, they develop a healthy rhizome and produce two, then three leaves, which increases the amount of photosynthesis the plant can conduct. The plants finally flower in year seven. Flowering and fruiting are energy intensive processes and it takes a robust, healthy rhizome with lots of stored starches to support reproduction. This process may be expedited in more southern locations like south Georgia or Florida, where plants may flower in year five. (Trout lilies have the same basic process of rhizome development, single-leaf years, and delayed flowering.)  We saw, at one little trillium patch, examples of one-, two-, and three-leaved plants growing together. It is suspected that trilliums are able to live for at least 100 years. 

Sweet Betsy trillium
Although most of the trilliums in the Dunson Garden are Chattahoochee trillium, there are several other species found at various locations, including the Sweet Betsy trillium. It has an upright, maroon or bronze-colored flower, with nearly closed petals. Like the Chattahoochee trillium, its leaves are mottled, almost camouflage-like, but lack the distinctive white to silvery stripe seen on along the mid-vein of Chattahoochee trillium leaves.
We saw a small patch of Trailing trillium, growing flat to the ground, and hiding their short (usually 1-2 inch) stems. The stem has a pronounced S-shape, which results in the leaves and flowers being held at ground level.
Trilliums can be divided into two groups: those with a flower stalk and those without (sessile). Chattahoochee trillium, Sweet Betsy trillium, and trailing trillium have flowers without stalks–their flowers sit directly on top of the leaves. Others such as the Georgia Dwarf Trillium and Catesby’s Trillium, have stalks that hold the flowers well above the leaves or sometimes curve downward, creating a “nodding” flower. Sessile trilliums have mottled, variegated leaves and yellow, maroon, or bronze-colored flowers. Stalked trilliums have solid green, unmottled leaves and flowers that come in various shades of white, pink, and maroon.
Georgia dwarf trillium
One of the highlights of the morning was the discovery that the Dwarf trillium are blooming. There is only one small location in the garden where this trillium can be seen and there are generally only a few plants to be seen. The scientific name for this plant will soon be officially changed to Trillium georgianum recognizing that it is a species separate from Trillium pusillum and acknowledging that it is endemic to the state of Georgia. The common name has also been changed to reflect its location; it is now Georgia Dwarf Trillium. The plants in the Dunson Garden were rescued from the original discovery location, which is threatened with development, in northwest Georgia near Dalton.

Painted buckeye buds have opened and the leaves are just emerging.

Spring beauty with closed flower bud
Eastern spring beauties have begun to bloom. We have been seeing the grassy foliage for several weeks but this week we now have flowers showing up. We saw several plants with tightly closed flowers this morning. They were just beginning to open and will be fully open later in the day when they receive more sun and warmth.
All the spring ephemeral plants have a short period of time in which they must attract pollinators and develop and disperse their seeds. Spring beauty is visited by several fly and bee species and one of these, the Spring beauty bee (Andrena eriginae), is a Spring beauty specialist. It is a solitary bee that depends almost entirely on gathering Spring beauty pollen to feed its larvae. In a single visit the Spring beauty bee can remove ~65% of the pollen from a flower. From the point of view of the plant this pollen is lost or stolen. The bee delivers only about 2% of the pollen it has collected to flowers that it subsequently visits. It would seem that the plant is a victim. But the bees stinginess is compensated by the frequency of its visits. At the time of year Spring beauty blooms the bee is the most abundant pollinator and responsible for most of the seed set by the plant. The bee, by exclusively relying on a single pollen source, stakes the life of its offspring on the success of its food plant. For if Spring beauty plants are eliminated by habitat disturbance, grazing by deer or competition from invasive species, then the Spring beauty bees will become extinct in that local area.
Early meadow rue
Early meadow-rue has just emerged and a few flowers are visible on the low mounds of vegetation. As the season progresses the flowering shoots will rise to a height of 2-3 feet. This is a dioecious species, meaning that the sexes are found on separate plants. When fully flowered, the male-flowered plants will delight us with a display of hanging purple and gold tassels (stamens whose pollen is dispersed by the wind). The flowers on the nearby female plant are really only conspicuous once they have produced fruits.
Trout lily leaves
The large patch of the Dimpled trout lily has leafed out beneath the large tulip tree.

Shooting star
We were all very excited to see several Shooting star plants with an abundance of flowers in an umbel gracing the tops of the tall, slender, leafless stems. At the base of the stems, there is a rosette of spoon-shaped leaves. These are among the most dramatic of spring ephemerals, with their brilliant white flowers, hanging downward with their five petals thrown backwards to present the visual effect of motion, thus the “shooting star.”  The scientific name Dodecatheon means twelve gods in Greek and was conferred by Pliny who believed that the Primrose family, of which shooting star is a member, was under the care of the twelve main Greek gods.
Cut-leaf toothwort
Just beyond the shooting stars, we saw several examples of Cut-leaf toothwort blooming, with their pale pink or white flowers.
Common blue violet
Common blue violets were visible just about everywhere we looked.
Dwarf pawpaw terminal leaf bud and flower bud

Dwarf pawpaw flower buds opening
The warm weather has caused the flower buds of Dwarf pawpaw to swell and develop. The flower buds are enclosed in hairy, bronze-colored scales that protect the flower from drying and freezing during the winter. New vegetative growth (leaves and stems) are not enclosed in bud scales and really only amount to a tiny, brown, sharply pointed, undeveloped leaf on an even tinier future stem. They are also minutely hairy, the hairs providing the only form of protection from winter’s cold and drying winds.
Golden ragwort young flower shoot

Golden ragwort flowers
Golden ragwort is present over much of the Dunson Garden and has just begun to bloom. There were many plants sporting numerous purple-colored buds. The purple color is due to the presence of anthocyanin, a compound present in many plants, such as cross vine, that acts as a natural “sunscreen,” protecting tender young leaves and flower buds from damage from the sun. There were a few plants that had fully opened flower heads atop their flower stems.
Wild ginger immature flower buds
Wild ginger leaves of various sizes and color are scattered about the Dunson Garden. Linda and Don began pulling back the leaf litter to look for the flowers, called “little brown jugs.” These flowers rest at ground level and are covered by dead tree leaves and the plant’s own evergreen leaves. We didn't find any “jugs” but we did find several white to cream-colored buds that resembled tiny bowling pins or, as some think, little pigs. One of the questions that arises from having flowers buried beneath leaf litter is what pollinates them. An interesting article on the controversy surrounding wild ginger pollination can be found here. A short summary: they self pollinate.  

Alleghany spurge male and female flowers
Just beyond the Georgia dwarf trillium is a large patch of the sprawling Allegheny spurge with large, mottled, evergreen leaves. Linda walked out into the patch and began looking to see if any flowers were hiding under the leaves. Several male and female flowers were found, in spikes 1 – 2 inches long; they may elongate up to 4 inches as spring progresses. Once fully developed, these spikes will give off a sweet fragrance that can be detected many feet away. The female flowers are found at the base of the spike and consist of 2-4 reddish to white bracts and a white stigma and style. The rest of the spike consists of many male flowers that consist of 4 white bracts and 4 – 7 stamens. Neither female nor male flowers have sepals or petals. Since the flowers are buried under leaf litter and the plant’s own evergreen leaves, there is still some question about how they are pollinated (just as with the flowers of wild ginger). The Japanese species of Pachysandra is a rapid spreader, making it popular as a commercial ground cover. Our native Allegheny Spurge spreads at a much slower rate and, though much more attractive than the Asian species, has not found a niche in the ground cover market. The Japanese species is also budding at this time in the Shade Garden; its flowers are held above the leaves in short but conspicuous spikes.
Seersucker sedge male and female flowers
We found several plants of Seersucker sedge in flower. Like most sedges in the genus Carex, the male flowers are held in spikes at the top of the flowering stalks, with the female flowers in spikes lower on the stalk. The male and female flowers mature at different times to prevent self-pollination. It gets the name seersucker sledge from the pleated appearance of the leaves.
The mature leatherwoods are about to finish blooming for the season. We found only a few flowers on the shrubs, with fruit starting to appear. Leatherwood has been spreading dramatically in the Dunson Garden the past several years. Some ramblers pointed out several clumps of densely packed, short, green woody stems of young leatherwood sprouts arising from the rhizomes that run rampant through the Garden.
Spicebush female flowers
Spicebush male flowers
Spicebush is now flowering. Spicebush is another dioecious plant, with individual shrubs being either male or female. Only the female plants will bear the bright red fruits later in the summer.
Running pine
(Southern) Running pine (aka Common Running-cedar) is found along the base of the hill in the lower section of the Dunson Garden. It is an ancient plant that reproduces by spores, dating from the time of the dinosaurs and before the evolution of flowering plants.
We were also fortunate to see the first bloom from one of the two Atamasco lily patches in the garden.
Virginia blue bells
Virginia bluebells are beginning to bloom, with their pink buds and blue, fully opened flowers both present on each plant. In the next week or so, the Virginia bluebell plantings should be awesome.
Kidney-leaf buttercup.
On a quick jaunt down to the river to look for yellow fumewort, Don didn't find any Fumewort but did find kidney-leaf buttercup in bloom on the Orange Trail.


Ginkgo tree
Ginkgo biloba 
Red maple
Acer rubrum
Bottlebrush buckeye
Aesculus parviflora
American hazelnut (filbert)
Corylus americana
Chattahoochee trillium
Trillium decipiens
Eastern spring beauty
Claytonia virginica
Early meadow-rue
Thalictrum dioicum
American (Yellow) trout lily
Erythronium americanum
Sweet Betsy trillium
Trillium cuneatum
Trailing trillium
Trillium decumbens
Painted buckeye
Aesculus sylvatica
Shooting star
Dodecatheon meadia
Cut-leaf toothwort
Cardamine laciniata
Common blue violet
Viola sororia
Dwarf paw paw
Asimina parviflora
Golden ragwort
Packera aurea
Dirca palustris
Wild ginger
Hexastylis arifolia
Dwarf trillium
Trillium pusillum
Allegheny spurge
Pachysandra procumbens
Seersucker sedge
Carex plantaginea
Lindera benzoin
Running pine
Diphasiastrum digitatum
 (= Lycopodium digitatum)
Atamasco lily
Zephyranthes atamasca
Virginia bluebells
Mertensia virginica
Kidneyleaf buttercup
Ranunculus abortiva
Japanese aucuba
Aucuba japonica

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