Today's Ramble was led by Dale Hoyt.
The photos in this post, except where
noted, came from Don's Facebook album (here's the link).
Today's post was written by Dale Hoyt.
34 Ramblers met today.
Announcements: Gary told us about the second annual Winterville Tree
Tour, April 14th. It will be
followed by a panel discussion on invasive plants in urban forests. Gary is on the panel. Two modes of control will be discussed, goats
and sheep, as well as herbicides. Check our
Announcements page for more details.
Today's reading:
I read a short passage from a Jane
Smiley essay published in the March, 2018, issue of The Atlantic:
What I realize as I travel through the landscape I once lived in . . .
is that when you are ready, you make use of what is right in front of you,
because everything can be inspiring if you are curious about it.
Eugenia read a poem, Nature Walk, by Gillian Wegener, that
was a selection of The Writer's Almanac for Wednesday, September 6, 2017. The
Writer's Almanac is no longer online, but you can read the text of the poem here. (My
comment: it was written about a 7 year old child, but could apply equally to
adults in the same situation.)
 |
| Beech bud, scales loosening and elongating. |
 |
| Beech leaves emerging from buds; on the right the bud scales are still present. |
Beech bud break is happening all
over the woods. Last fall we saw the formation of the long, pointed
cigar-shaped beech buds, each one capable of putting an eye out. Now they are
eye-stopping in another way. The tan and brown bud scales are not just dropping
off, they are actually elongating as they loosen to reveal the new growth
hidden inside: the twigs, leaves and, in some cases, the flowers. Each of these
structures formed over the last six or so months and they will now rapidly
assume their full size over the next few weeks. Increase in the size of the bud
contents is accomplished by the enlargement of the cells produced last fall and
winter. Each cell in the shoot and leaf elongates by imbibing water. The cells
swell and elongate and the leaf or twig lengthens accordingly. If you get a
chance look at an emerging leaf. Be amazed by the origami folds that enabled it
to be packed inside the bud and then unfurled into its adult form. Such
packaging has been the inspiration of NASA scientists in the design of the
solar panels that power many satellites – compressed in their bud, the launch
rocket, and then unfurled when the payload reaches its orbit.
When a tree falls in the forest what kind
is it? If the forest was in our Botanical Garden and you said Northern Red Oak (NRO) you'd be right
most of the time. Why this particular kind of tree should be so prone to
tumbling over is not precisely known, but we can make some educated guesses.
 | |
| A large tip-up; shallow root system, no tap root. (Photo by Bill Sheehan) |
In many areas of the garden the rocks
are near the surface and a tree can't sink its roots deeply enough to prevent
falling in a wind. That's a good reason for tree falls in the garden, but why
would NROs be more susceptible? NROs don't have a tap root, as you
can see by looking at the bottom of a tip up. As a tree grows taller the wind
blowing on the lever arm of its trunk exerts a greater force on the roots. This
would make the NRO more susceptible to wind throw than other tree species.
 | |
| Northern Red Oak; new shoot with unexpanded leaves, male catkins. Toward the end of the shoot the small red structures are female flowers (see enlargement below). |
 | |
| Northern Red Oak female flowers; the pistil is too tiny to be clearly visible, even with this enlargement. |
 | |
| Other monoecious trees: Sweet Gum; the fuzzy balls above the leaves are the male flowers; the tiny ball hanging down below the leaves is the female inflorescense. It consists of numerous flowers and will develop into a "gum ball" in the fall. (Photo by Dale Hoyt) |
 |
| Other monoecious trees: Southern Red Oak; new leaves and male inflorescenses. (Photo by Dale Hoyt) |
 |
| Other monoecious trees: Water Oak; new leaves and male inflorescenses. (Photo by Dale Hoyt) |
Early spring is the time of year when
many trees flower. Some, like Red Maples and Winged Elms have already finished flowering
and are setting seeds right now. Other wind pollinated trees are currently
blooming, even if you don't see conspicuous "flowers." They have
plenty of flowers, they are just not attractive to the eye because they lack
showy petals. In fact, many people are aware that oaks produce pollen this time
of the year, but they don't associate the oak catkins with flowers. Each catkin
is a long clusters of male flowers that lack petals. It's the lack of petals
that makes them appear so un-flowerlike. They also lack a pistil, the female
part of a flower. So where are the female flowers? You'll have to look
carefully on the new growth, preferably with a hand lens. Right now the female
flowers are tiny, solitary, red nubbins. With the hand lens you can see the
pistil. Each tiny flower will, if it receives a pollen grain, produce a single
acorn. In the red oak group it takes two years for a mature acorn to develop;
white oak group acorns develop faster, maturing in the fall of the year they
started development.
The sex life of trees is
complicated by the presence of unisexual
flowers, as seen in the NRO. The typical flower you may have learned about in
school has both pollen producing structures (the anthers, at the end of the
stamens) and seed producing structures (the pistil(s)). Such a flower is termed
a perfect flower. Other terms for a
perfect flower are bisexual or hermaphroditic. When a plant has male
and female unisexual flowers that are found on the same individual plant the
condition is called monoecious. (The
word is derived from the Greek word meaning "one" and the Greek word
meaning "house." They were then Latinized. Pronunciation:
moh-NEE-shus.) The NRO is a monoecious species. All of the oaks in our area are
monoecious, as are most maples and ashes.
Other tree species have unisexual
flowers that are born on different individual plants. This is the dioecious condition. (Pronunciation:
"die-EE-shus;" jt's latinized from Greek words meaning "two"
and "house."
Summarizing:
Monoecious, means "one house;"
unisexual flowers of two types are found on the same individual plant.
Dioecious means "two houses;"
unisexual flowers of only one type are found on an individual plant. Male and
female flowers are found on different individual plants.
The upshot is that, in plants, the
terms male and female really only applies to the flowers, not the whole plant,
except in the case of dioecious plants.
 | |
| Box Elder leaves. Each leaf typically has three leaflets, making it look like Poison Ivy, but it is harmless. Box Elder is a kind of maple and has opposite leaf arrangement. |
 | |
| Dioecious tree: Box Elder female flowers hanging down from new shoots. |
 | ||
| Clusters of Box Elder female flowers. Each long thread ends on the right with two tiny green fruits, not mature in this photo. (Photo by Dale Hoyt) |
 | |
| A cluster of Box Elder fruits. (Photo by Dale Hoyt) |
 |
| Two Box Elder flowers, each with two developing fruits. They are now recognizable as typical maple-style fruits; the swellings at the point of attachment to the flower stalk contains the seed. (Photo by Dale Hoyt) |
An example of a dioecious tree species
is the Box Elder, a type of maple. (It is sometimes called the Ash-leaved
Maple.) We saw some large female Box Elders on today's ramble. At a distance
their female flowers looked like dense clusters of silken strands. At the tip
of each silky stalk there are two developing fruits that become the typical
maple "helicopter" seeds. (The thing that spins through the air when
dropped is often inaccurately called a maple seed. The seed is just the part enclosed
at the swollen end of the wing. The wing plus enclosed seed is properly called
a fruit.)
But wait, there's more! Some plants
mix things up even more. You'll find plants with perfect flowers and male
flowers on the same individual. Or perfect flowers and female flowers on the
same individual. Some monoecious plants will produce different proportions of
male and female flowers each year; one year they have mostly male flowers, the
next they may have mostly female. Other kinds vary the sex of flowers on the
same branch from year to year. Why these variations occur and how they evolve is
the subject of ongoing research.
 |
| A dense stand of Butterweed along the Orange Trail at the river. |
 | |
| Butterweed flowers |
 |
| Butterweed leaves; note the large lobes. |
 | |
| Butterweed: the whole plant |
 | |
| Golden Ragwort for comparison with photo above. |
Huge stands of Butterweed are to be seen on the Orange Trail along the river. This
species is one of the ragworts in the genus Packera
(formerly the genus name was Senecio.
Now the New World ragworts are known to be more distantly related to the Old
World ragworts, so they are all placed in a genus of their own.)
Earlier this year we saw the Golden
Ragwort, Packera aurea, blooming in
the Dunson Garden. Butterweed look like those of Golden Ragwort but other
features differ in several respects: it is an annual plant. It has a thicker,
hollow flowering stalk and the stalk and basal leaves are dissected into many
lobes, each about the same size. (Golden Ragwort basal leaves are undissected
and kidney shaped and the stalk leaves are dissected into many smaller, finer
lobes.) Golden Ragwort is a perennial; its basal leaves overwinter.
Perennials and Annuals
One characteristic of perennial plants
is that they usually have a way to survive over the non-growing season. For
some they overwinter as a basal rosette of leaves that hug the ground; e.g.,
Dandelions. Underground storage organs like bulbs, rhizomes or taproots hold
energy supplies that enable the perennial plant to get a head start the
following year.
Annual plants put all their energy
into producing fruits and their contained seeds. This is done at the expense of
the other plant parts. A general ecological principle is at work here. An
organism has a limited supply of energy that it uses for different purposes.
Broadly speaking, these can be divided into three categories: growth,
maintenance and reproduction. Like your income, what is spent on one cannot be
used for another. A plant is, in effect, faced with a decision. In order to get
more energy (food) it has to grow (produce more roots, stems and leaves). The
more roots, stems and leaves it has means that an increasing amount of its
energy must be devoted to maintaining them. So if it is going to make flowers
and seeds it will have to use some of the energy that would otherwise go to
growth and maintenance. The difference between annual and perennial plants is
in how they allocate that energy. An annual plant "decides" to spend
it all on seeds and lets the roots, stems and leaves die. A perennial makes a
different allocation. It might, for example, store some energy in a root,
rhizome or bulb and let the above ground parts wither away and die. It might
forego reproduction in an unfavorable year and save the stored energy for the
next year.
It's not always obvious if a plant is
an annual or a perennial. One rule of thumb you can use is to look at the root
system. A perennial will usually have some sort of underground storage, like an
enlarged taproot. An annual plant will usually have a fibrous root system, like
the Butterweed I showed you.
SUMMARY OF OBSERVED SPECIES:
American Beech
|
Fagus grandifolia
|
Sourwood
|
Oxydendrum arboreum
|
Northern Red Oak
|
Quercus rubra
|
Painted Buckeye
|
Aesculus
sylvatica
|
Silverbell
|
Halesia sp.
|
Lyre-Leaved Sage
|
Salvia lyrata
|
Atamasco Lily
|
Zephyranthes
atamasca
|
Butterweed
|
Packera glabella
|
Oriental False Hawksbeard
|
Youngia japonica
|
Bedstraw
|
Galium aparine
|
Box Elder
|
Acer negundo
|
Toadflax
|
Nuttalanthus
canadensis
|
Ground Ivy
|
Glechoma
hederacea
|
Purple Dead Nettle
|
Lamium purpureum
|
Virgin's Bower
|
Clematis
virginiana
|
Sweet Autumn Clematis
|
Clematis
terniflora
|
Beaked Corn Salad
|
Valerianella
radiata
|
Giant Cane
|
Arundinaria
gigantea
|
