Leader for today's Ramble: Dale
Link to Don's Facebook album for this Ramble. All the photos that appear in this report, unless otherwise credited, were taken by Don Hunter.
Number of Ramblers today: 29
Today's emphasis: What's happening on the Orange Trail
Reading:
Show and Tell: Dale brought a Sweetgum inflorescence. Sweetgums are monoecious -- their flowers are either male, bearing stamens that produce pollen, or female, bearing flowers that will produce seeds. Both sexes are found on the same plant. (If the sexes occured on separate plants, they would be called dioecious. The two kinds of inflorescences look very different. The male inflorescence is a tall, lumpy cluster of pollen producing flowers that the tree drops soon after they exhaust their pollen supply. The female inflorescence develops into a spikey globe about the size of a golf ball. They drop off the tree in autumn, just to annoy you when you step on them barefooted.
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Sweetgum inflorescences
uppermost is a group of male flowers
The spherical structure in the middle, just in front of my finger, is the female inflorescense
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Announcements:
Next week's (April 14. 2022) Nature Ramble will be held at Sandy Creek Park (the Park, not Sandy Creek Nature Center). Click here for directions.
Sue introduced her sister, Emily, from Boston.
Today's Route: From our meeting place we walked between the Ceramic Arts bldg. and the Visitor Center, then followed the sidewalk to the Meditation area and turned left on to the Orange Trail Spur, which we followed to the Orange Trail where we turned left (upstream)
OBSERVATIONS:
Flower Garden Path to Orange Trail Spur:
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Little Brown Jugs; one flower revealed at the top of the photo by removing the leaf litter
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Little Brown Jugs are named for their flowers that are hidden in the leaf litter. Why would a plant hide its flowers from view? Pollination biologists discover potential pollinators by patiently peering at the visitors to a flower. This won't work for Little Brown Jugs. Their buried flowers make it impossible to see what visits the flowers. If the leaf litter is cleared away the pollinator may be discouraged from visiting an exposed flower. An indirect approach is to bag the flowers with a fine mesh cloth and leave other flowers unbagged. If the seed production of bagged and unbagged flowers is the same then the plant is likely to be self-fertilizing. This does seem to be the case, as reported by this brief paper: Don't Judge a Book by its Cover: The Curious Case of Wild Ginger Pollination :
Orange Trail Spur and Orange Trail (moving upstream):
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American Beech with "Warty" bark.
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American Beech tree warty bumps on the bark, We've visited this tree for 12 years with no evidence that the warts have damaged its health. It has been suggested that the warts are Beech Bark Disease (BBD), a serious problem in the Northeast states where thousands of Beech trees have been killed. BBD is caused by a fungus that invades bark damaged by scale insects. For pictures of BBD and more information consult this brochure from the University of Massachusetts. https://ag.umass.edu/landscape/fact-sheets/beech-bark-disease
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| Jack-in-the-Pulpit |
Jack-in-the-Pulpit (JP) When young the single leaf with three leaflets can be confused with a Trillium. Here's how to tell the difference: imagine a circle with a stem growing up from the center. At the top of the stalk there are three leaflets, two of which are aligned with the diameter of the imaginary circle. The third leaflet is perpendicular to the diameter. That's a JP.In a Trillium the three leaflets emerge from the center of the circle in a Y-pattern, but all three angles are equal to 120 degrees; no two of the leaflets lie on a diameter.
Previously we called all the JP in the Botanical Garden, Arisimea triphyllum, but recent opinions have caused a re-think.
Jack-in-the-pulpit is widely distributed in eastern North America and has been treated as a single species with several subspecies, forms or varieties.
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Jack-in-the-Pulpit with 5 leaflets
(photo from 2014 ramble)
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The 2017 version of Weakley's Flora of Georgia recognizes an additional species in our area: A. quinetum, formerly treated as a subspecies of A. triphyllum. It has 3 to 5 leaflets. But why should it be considered a distinct species, rather than a variety, subspecies or form. Is it solely a matter of judgement?
Species concepts. A widely accepted definition of a species hinges on the concept of reproductive isolation. Reproductive isolation means that, in nature, individuals of different species do not mate with one another, or, if they do, the resulting organisms have lower fitness. In the case of the two JP species there are more differences than just the number of leaflets; they have different numbers of chromosomes. A. triphyllum is tetraploid and A. quinetum is diploid. A cross between these two is a triploid plant. It has three sets of chromosomes, one set from quinetum and two sets from triphyllum. The triploid can reproduce vegetatively by budding of the rhizome, but it is sexually sterile. Therefore quinetum and triphyllum are reproductively isolated and best viewed as distinct species.
Why triploids are sterile. You probably remember that during the formation of eggs and sperm the chromosome number is halved. For example, humans are diploid; they have two sets of 23 chromosomes. Their eggs and sperms carry 23 chromosomes, one from each of the 23 pairs of chromosomes. To produce eggs or sperm the chromosomes pair up and the sex cells get one member from each pair.
A triploid has three sets of chromosomes. When the chromosomes prepare for the cell divisions that produce sperm and eggs they attempt to pair up. But with three sets of chromosomes there is always one pair and a loner. The two paired chromosomes separate from one another and the singleton goes randomly into one or the other of the sex cells. This is happening to each chromosome in each set.
The result is a mixture of singles and doubles of each chromosome. Consequently some of the genes are present in one dose, others in two or three doses. This causes defects in gene expression that cause the developing seed or pollen to abort.
Wild Geranium
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A female Wild Geranium lacks stamens.
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A hermaphroditic Wild Geranium has both male (stamens) and female parts (pistil)
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Wild
Geranium is currently blooming and we
found many plants along both the Orange Trail Spur and Orange Trail. In this area the plants are of two types: those
that have both stamens and pistils (called perfect flowers, bisexual flowers, or hermaphroditic flowers), and those that
lack stamens (pistilate flowers).
(Remember: the stamens produce pollen, the pistil holds the egg that
develops into the embryonic plant inside the seed.) This condition, where a species has two types
of flowers, perfect or female, is
called “gynodioecious” (pronounced: Gy-no-dye-E-shus). (Note that this
term applies
to the population or species, not the individual plant or flower.)
Gynodioecy may be a stepping
stone on the way to evolving into a species in which there are only two kinds
of plants, those with male flowers and those with female flowers. That
condition is called dioecious (pronounced: dye-E-shus). Examples of dioecious species we have seen in the Garden are Spicebush and the various holly species.
Plants have two ways of passing
their genes on to the next generation: via seeds or pollen. If a plant loses
the ability to produce pollen you would think that it would lose the
evolutionary race to those that produce both seeds and pollen. But making pollen takes energy
and a plant that doesn’t have to make pollen can divert more energy to produce more
or larger seeds. That could give it an advantage over the plants with
perfect flowers.
If the female only plants produce more seeds that inherit that trait then they will increase in frequency in the population. But this means that there will be fewer plants producing pollen. Eventually, as pollen becomes less available, the pistilate plants advantage in seed production will decrease because there are too few pollen producers. Then the plants that are producing pollen have the
evolutionary upper hand and they will start to increase. It would seem to be
pretty difficult to evolve into a dioecious species from a gynodioecious one. Not producing pollen may be advantageous when it is rare, but as it becomes more numerous it loses that advantage. (This is an example of frequency-dependent selection.)
Christmas Fern
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| Christmas Fern fertile frond showing the pinules that bear the spore producing structures near the end of the frond. |
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Often we are guilty of ignoring the commonplace. I plead guilty of this when it comes to Christmas Ferns. It seems to grow almost everywhere, yet I can't really answer the symplest questions about it's biology. Here are a few examples.When the new fronds emerge in the spring not all of them develop into fertile fronds. How many will form on a single plant? Does the number depend on how much light the plant is exposed to? Or the age of the plant? Did the overwintering fronds supply any energy to the new fronds? What would happen if someone were to cut off part of the winter fronds? Would that affect the number of new fronds or their fertility or both or neither?
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Strange object gripping the top of a Mayapple leaf.
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Object removed and broken in half.
Recesses in the open surface suggest it held seeds. |
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The white object in the photos above looked initially like a gall growing from the center of a Mayapple leaf. But it wasn't really attached to the leaf. It looked like might have been an empty seed capsule that had accidentally fallen to the surface before the Mayapples emerged. Then one leaf poked up into the hollow center of the capsule and found its leaf confined by the capsular walls. We couldn't figure out what plant the capsule came from.
Another Mystery Object
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What is this thing?
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Heather found a curious object firmly attached to a beech twig. One end was rounded, the other, had what looked like a lid. You could bend the flap or lid open with a finger nail and, when released, it snapped shut. Heather and Don guessed that it might be cocoon of some moth, but it didn't look like that to me. Most cocoons have the texture of fine silken threads, but this thing didn't, at least to my poor vision.
Click beetle
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Click Beetle
Head is to left, followed by 1st thoracic segment, then the wing covers that extend over the last 2 thoracic segments and the abdomen. |
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A click beetle is named for the unusual way it has of righting itself. When placed on its back it is helpless. How to get back on its feer?! While on its back it bends its head-thorax upward toward its belly. The head-thorax suddenly snaps down, hitting what it's lying on with enough force to propel its body upward, spinning in the air, and emitting a sharp "click." This action is repeated until it lands on its feet.The sadistic entomologist, or small boy, can deliberately turn a click beetle several times to discover how many times it takes to fatigue the poor beetle.
Post-Ramble Observations:
After leaving the Orange Trail and cutting over to the upper parking lot, I noticed a lot of activity on the large Chinese Holly hybrid (according to Gary). The abundant yellow flowers were attracting a wide assortment of pollinators, including: Western Honey Bee, Common Flower Fly, Eastern Carpenter Bee, tachinid fly, halictid bee, Transverse-banded Flower Fly and Potter Wasp
SUMMARY OF OBSERVATIONS:
Pre-Ramble
Chattahoochee Trillium Trilium decipiens
Doublefile Viburnum Viburnum plicatum tomentosum 'Mariesii'
Mount Airy Fothergilla Fothergilla major 'Mount Airy'
Flowering Dogwood Cornus florida
American Beech Fagus grandifolia
Confederate Azalea Rhododendron 'Semmes'
Green-and-Gold Chrysogonum virginianum
Wild Ginger Hexastylis arifolia
Jack-in-the-Pulpit Arisaema triphyllum
Solomon's Seal Polygonatum biflorum
Three-parted Yellow Violet Viola tripartita
Wild Geranium Geranium maculatum
Christmas Fern Polystichum acrostichoides
Elliott's Blueberry Vaccinium elliottii
Mayapple Podophyllum peltatum
Carolina Anole Anolis carolinensis
Orchard Orbweaver Leucauge venusta
Rattlesnake Fern Botrychium virginianum
Wood Ear Mushroom Auricularia auricula
Bloodroot Sanguinaria canadensis
Coral Honeysuckle Lonicera sempervirens
Click beetle Gambrinus sp.
Jack-in-the-Pulpit rust fungus Uromyces caladii
Buckthorn Bully Sideroxylon lycioides
Perfoliate Bellwort Uvularia perfoliata
Mayapple Rust fungus Allodus podophylli
Hooked Buttercup Ranunculus uncinatus
Wood Rush Luzula glomerata
Elm (with galls) Ulmus sp.
Slime Mold ?? Fuligo septica ??
Broad Beech Fern Phegopteris hexagonoptera
Rue Anemone Thalictrum thalictroides
Common Blue Violet Viola sororia
Common Chickweed Stellaria media
Kidney-leaf Buttercup Ranunculus abortivus
Bedstraw Galium aparine
Southern Chervil Chaerophyllum tainturieri
Eastern Tent Caterpillar Malacosoma americanum
Post-Ramble
Western Honey Bee Apis mellifera
Common Flower Fly Syrphus ribesii
Eastern Carpenter Bee Xylocopa virginica
Tachinid fly Family Tachinidae
Halictid bee Halictus sp.
Transverse-banded Flower Fly Eristalis transversa
Potter Wasp Euodynerus bidens
Photos by Heather Larkin
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Red-bellied Snake
small, eats slugs and snails |
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Red-bellied Snake Storeria occiputomaculata
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| White-banded Fishing Spider |
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White-banded Fishing Spider Dolomedes albineus
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| Chestnut Carpenter Ant |
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Chestnut Carpenter Ant Camponotus castaneus
