Showing posts with label Acer saccharum. Show all posts
Showing posts with label Acer saccharum. Show all posts

Monday, August 8, 2016

Minor Mystery



What do you notice about the two sides of this sugar maple?


At first glance, I took the difference between the left and right sides of this majestic sugar maple to be simply a trick of the light.  Then I realized the left side really was fuller and darker than the right, but thought it might get more light on the left.  But the photo is taken from dead south, and there's nothing nearby tall enough to shade it.  I've noticed this difference now two years running.  Hmmm.

I'm still not sure of the explanation, but I have a hypothesis.

All plants except mosses and liverworts  get water from roots to crown through a tissue called xylem, that runs up through wood of the trunk.  Xylem is composed in flowering plants mostly of dead cells like stacks of barrels with the ends knocked out, making long pipes called vessels.  (If you look closely at the end of a recently-cut log you can often see the ends of these vessels like little pores in the wood.)  The vessels run from roots to trunk to branch to twig to leaf stem to leaf vein, and supply all the cells with water and nutrients.  There is some communication from vessel to neighboring vessel, but probably not much.

My hypothesis is that the vessels from roots on the right hand side of the tree mostly serve branches on that same side, and so with the left.  Notice that the right side is right next to pavement: either there are few roots alive under that pavement, or the roots there get less water because the pavement prevents most of it from infiltrating into the soil.  This has starved the right side of water and probably nutrients, and led to relatively sparse leaf growth on that side.

Well, it's just a hypothesis.  But I haven't found a better one.

The large holes in red are the water-carrying vessels seen end-on.
http://pysssec3biology2010.wikispaces.com/

Beautiful scanning electron micrograph of xylem with large vessels above,
light micrograph of xylem cross section below.
https://simple.wikipedia.org/wiki/Xylem_vessel

Nice cartoon of the whole process, from water entry into root to evaporation from leaf.
https://www.boundless.com/biology/textbooks/boundless-biology-textbook/plant-form-and-physiology-30/

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Meanwhile, it's the second week in August and the drought only deepens.  Our area has only received a fraction of the average spring and summer rainfall (much less than I reported in a previous post).  This particular tree has lost keys and leaves.  Nearly all the black and red oaks in the neighborhood have aborted and dropped acorns on the ground.  This time last year was pretty dry also, but I didn't see fallen acorns then.

It's too early in the season to be seeing fallen sugar maple leaves.

 The red oak acorns are falling unripe, even though they only have a few weeks to go.
These scarlet oak acorns are getting thick on the sidewalk beneath.

Monday, February 15, 2016

Eight (or so) Trees You Can Readily Identify in Winter


With the leaves gone, the upswept branching pattern of sugar maple trees is more striking than ever.  This got me wondering if I could do a "tree silhouettes" post.  But as I walk around, I find no other trees as easy to distinguish at a glance as sugar maple.  Without their leaves, identifying trees can be tricky.  Nevertheless, some trees have peculiarities that make it easier.  Here are some easy calls, beginning with conifers.


1. White pine (Pinus strobus) is very easy to distinguish, with its long, thin needles (in groups of 5), feathery branches, and a typically blue-green color.  They are distinctive enough to be identified at highway speed--even more so in winter, since they keep foliage year-round.

 The white pine above is losing needles (as they do in fall), which makes it
look yellowish rather than the usual blue-green. (I see dying needles
on the highway, as well.)  Up close, the needles are two-colored.


Other common pines in the area are red pine, an alien which has distinctly reddish bark and coarser needles,  and pitch pine, with its more yellow-green color, thick, stiff needles leading to a "bottle brush" appearance, and the fact that this drought-tolerant pine is most often found on well-drained sandy soils.

 Pitch pine (Pinus rigida) has sparser, thicker, stiffer needles than white pine.  Its cones are small and round rather than long, and pointed, and the scales are armed with very sharp spines.


2. The alien invasive Norway spruce (Picea abies), with its dangling branchlets, and big, long, cylindrical cones is easy to spot.  This tree is common in yards despite the deep shade it casts, and the near-impossibility of growing much of anything under it.  Birds do love its shelter in winter, though.

 Beside the very distinctive drooping branchlets,
Norway spruce has large cones that taper abruptly at the tip.

3. A third conifer is eastern hemlock (Tsuga canadensis).  It has short needles, but the branchlets don't hang the way Norway spruce does.  The needles are flat and striped beneath.  In the wild, eastern hemlock is a stately tree, but homeowners ignorant of its true nature sometimes condemn to be a mere bush or hedge, tortured regularly with pruning shears.

 Another easy-to-recognize conifer is the stately eastern hemlock, with its short, flat needles decorated beneath with light-blue racing stripes, and cones no bigger than your little finger end.

Flash photography brought out the "racing stripes" in these eastern hemlock needles.

A final edit, and one more conifer.  Taking to the highway today, I realized that oldfield juniper (aka eastern, aka etc.) shared the roadside with white and sometimes pitch pines.  But it's usually easy to distinguish by its silhouette.


Eastern juniper (Juniperus virgianiana) is a tree common to oldfields and roadsides
and is rather seldom planted.  On the highway, you can easily tell its by its narrow,
tapering or tear-drop silhouette from broader, more open crowns of pine.

Some, but not all, oaks hold some of their dead leaves through the winter (a trait called "tardily deciduous").  Other than that, oaks cannot (in my experience) be distinguished in winter at a distance.   Up close, you might notice that the tips of oak twigs are crowded with buds.  

4. One oak that can be distinguished is white oak (Quercus alba): its bark is light to medium gray, and up close often looks a little like overlapping vertical shingles. I don't know whether white oak got its name from the having lighter bark, or from the light color of the undersides of its leaves.  The crown varies in shape.  

  Above are two white oaks, below are two other (probably black) oaks for comparison.

If you can reach a twig, white oak buds are small, round, fat and hairless. 

Here are the crowns of a few white oaks to give you an idea of their gnarlyness and range of shapes.  Notice that the two are holding dead leaves low in their crowns, as is most typical.  Here is white oak during the growing season.


Maples are easily distinguished from most other locally common trees by having opposite leaves and buds--rather than alternating from side-to-side as oaks (for example) do.  Red and silver maples have large enough buds that you can often see this even when a branch is too high to reach.  

5. Sugar maple (Acer saccharum) is told at a distance by the gracefully upswept branches that divide low on the tree, so that there seems to be no clear central trunk for most of its height.  Within the maples, sugar maple has bark that breaks into plates in the mature trunk, while most others have vertical ridges that form a net pattern.  Red maple is in-between: the mature trunk bark somewhat platy but not as much so as sugar maple.

Three sugar maples in a row are clearly identified by the upswept branches 
and absence of a central trunk.

Buds of silver maple (above) and red maple (below).  Easier to see than paired buds in the silver maple, some twigs are also paired (see especially the little twig in the bottom right corner above). 

 Paired buds of ash-leaved maple.

Here are the trunks of a few maples.  And here is sugar maple during the growing season.

The deeply-ridged and platy bark of older sugar maple.

 The bark of red maple is fairly distinctive in mature trunks (above), 
but not young trunks (below).

 Norway maple trunks have a network of ridge (above), as do trunks of unrelated white ash (below).

6. Shagbark hickory (Carya ovata) has very distinctive bark that peels off mainly in winter in long, stiff, jagged pieces.  Not a very hug-able tree!



7. While not all birches have smooth, white bark, two that do are paper birch (Betula papyrifera) and gray birch (Betula populifolia).  If the old bark low on the trunk doesn't look convincingly white, look aloft at higher limbs.  The two species are hard to distinguish at a glance, but paper birch grows larger, and gray birch tends to have dark triangles that are the scars of fallen branches.  In summer their leaves give them away: paper birch are more rounded, gray are more triangular with long, tapering points.

The three photos below are all of the same paper birch, the fourth is a different individual.



Below, for comparison, are two different gray birches.  The dark markings where branches emerged are generally more pronounced in gray birch, but the distinction isn't that easy.  Better to wait for the leaves

 Gray birch (Betula populifolia).

8. American sycamore (Platanus occidentalis) is a large native tree.  (Okay--now this really IS my last edit.)  Spotting some sycamore trees in downtown Providence reminded me that I know of two sycamores in my neighborhood--and sycamore is certainly easy to identify.  If the jigsaw puzzle-like bark isn't obvious, you might notice the lollipops hanging from the branches.  These spherical clusters began dispersing seeds dangling from dandelion-like parasols back in the fall, but they aren't done yet.  You might spot the clusters of downy seeds on the ground (as I did in Providence) before noticing the trees themselves.


Multicolored bark that peels off in pieces that look like jigsaw puzzle pieces instantly mark
this as sycamore.  Lollipop-like fruit structures may drop tufted seeds far into winter. 

Monday, October 12, 2015

Subtle Colors

"Peak color" in the fall is a thing to glory in.  I have already seen announcements for tours up north to view peak color at these higher latitudes where it comes earlier, and it will be here soon enough.  But the more subtle color at this time of the season has charms of its own.  Here are a few trees to look for right now.

Sugar maples have been turning by ones and twos for quite a while.  Sadly, many of these lose their leaves even as they turn, so that you'll notice more color on the ground than in the sparse crowns above.  (Those that hold their leaves will often finally reach a brilliant flame orange that is truly breath-taking.)

Precocious show-off, September 12th.

Trees turn individually, and even by parts.  Early October.

Sugar maple leaves often fall immediately after they turn.

Foretaste of the color to come.

Red maples have been sidling (edging) into the season, first with red leaf-stems, then red leaf edges, until whole leaves begin to turn.

 "Little Mama" September 22nd  (Hey--gotta call 'em something!)

 October 3rd.

 October 11th.

White ash is quietly going bronze.  This is a fairly unusual color, and handsome rather than gaudy.  Enjoy it while you can: the imminent arrival of the alien invasive Emerald Ash Borer beetle will doom most ashes in the area, even as it has elsewhere in North America.  If you can find a female tree, you might collect a few samaras and plant a tree in your yard; they can be kept alive in spite of borers if treated with the right insecticides.

Samaras (winged seeds) hanging in a female white ash amid a few turning leaves, 
September 25th, October 3rd.


Large and small white ashes, October 10th

One thing that I never cease to marvel at is how parts of a tree will turn quite a long time before other parts.  About this time last year I explained what makes trees turn the colors they do when they do, but this is a different effect.  As animals ourselves, we are most familiar with animal life, in which there is (usually) a brain and (almost always) a nervous system to coordinate changes throughout the whole body.  Plants have neither brain nor nerves.  They also have no circulatory system (heart and blood vessels), though they do have a system of xylem to transport water and minerals from roots to tops, and a parallel system of phloem to transport sugar from leaves toward roots.  (In trees, the xylem is typically in the "sap wood," while the phloem is in a thin layer inside the bark.)  This transport system also serves to move hormones around that work a bit like animal hormones. 


 Local effects of some sort: the entire eastern side of this sugar maple has turned
while the western side is still green.  (October 5th & 10th)

But on the whole, a plant's life is much less centralized and much more "local" than that of animals.  The conditions that trigger leaves to color and then fall act only on those parts of the tree they reach; other parts of the tree must be triggered separately as the conditions vary in time and space.  I remember as a botany student at the University of Rhode Island coming upon a Norway maple tree beside the drive to the Student Union.  A street light was nestled in its branches, and when the rest of the tree was wearing its autumn tint of clear yellow, a globe of leaves around the street light was still green: the night-time glow of the streetlight having prevented the nearer leaves from responding to the longer nights of autumn.  Those leaves remained green as weeks passed and the rest of  the tree became bare, until they finally died shredded to tatters in the winter cold and wind, never really having been "aware" that fall and winter had come.

To put the idea in perspective, imagine standing in very cold water: if you were like a plant, only your feet would feel cold, and only your feet would shiver. 

Such is the diffuse, local life of a tree. 

  I sometimes try to figure out why a certain part of a tree has turned earlier or later than another; it's worth the attempt, I think, though I have never satisfied myself that I knew what subtle gradient of light or temperature from one part of the crown to another had made the difference.  

A few less subtle.

 Poison ivy is worth watching at this time of year--but not too close.  10/10


Virginia Creeper (Parthenocissus quinquefolia) and Flowering Dogwood (Cornus florida) turn partly to attract migrating birds that, here in the city, probably won't come.  9/11, 9/29