White Pine Orgy

 Doing my part for my white pine (Pinus strobus) neighbors.

The white pines in the neighborhood seem to have grown male cones almost overnight, and these began shedding pollen just a few days ago.  Today they were going full force, and will be turning cars and sidewalks dusty yellow over the next several days.  On the other hand, it will be over quickly; last year the whole orgy was over in only seven or eight days (beginning a few days earlier than this year).  And white pine pollen, though wind-borne, is heavy enough that it doesn't typically remain in the air long, and does not cause the allergy problems that some other air-borne pollens do.  It's just vegetable love!

 Pollen cones are smaller than your little finger tip, but very abundant!

 The male cones are in clusters of a dozen or more on nearly every sunlit twig.

 Though larger, the female cones are fewer, higher up, and not showy.

They hang down from the twigs.

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. 

Everlasting Pine Needles

My wife tells stories of her Catholic education.  One that I enjoy is the high school science teacher who insisted that pine trees don't drop their needles.  Asked by observant girls how the pine needles they found on the ground got there, the nun opined that squirrels nibbled them off.

White pines of my acquaintance beg to differ.

Needles turning yellow alter the appearance of the whole tree.

 

I had been taught that pine needles lasted two seasons, so that each fall the previous year's needles fell,* leaving the present year's still on the tree.  That seems true of the twig above.

But the reality can be more complicated.  I have seen needles yellow and fall in spring as well.  Are these needles that lived through a second winter? or are they last year's needles falling prematurely?  I think it's the first, but I didn't mention it in my journal last spring.  I'll have to watch closely over the coming months.

I think I have also noticed these out-of-season needles yellowing and falling individually--sometimes leaving others in the same cluster alive.

Whatever the case, the needles fall.  And from a big tree, the result is drifts big enough to be obvious even to the most obtuse.  

But how are any pine needles retained through the harsh winter months, when broad-leaved trees in this climate nearly all lose theirs?  Cold is only one of the stresses, and not the chief.  Carrying leaves over the winter means losing water when liquid water is scarce.  I also suspect that carrying broad leaves risks wind damage at a season winds are strongest.  With days so short and sun angles so low, there simply isn't enough benefit from photosynthesis to be worth the cost.  

Pines, though, have needles that are adapted to drought.  Needles are thickly coated in water-proof wax.  Their stomata (pores) can be closed more tightly to limit water loss.  Also, the stiff needles don't depend on internal water pressure (as most broad leaves do)* to maintain their shape.  And needles present less resistance to wind than broad leaves.  These adaptations, plus the ability to do photosynthesis year-round whenever conditions permit, plus the huge benefit of not having to grow a full set of leaves every spring, all tip the balance in favor of pines being evergreen.

Here is a concise but wide-ranging discussion of winter adaptations of trees.


*Actually, autumn leave don't just die and fall off, they are actively shut down, some of their most valuable nutrients recycled, and then they are "deliberately" cut loose.
**Wilt is the condition of having too little internal water pressure to maintain shape; a leaf is like a football: nearly rigid when fully inflated, very floppy when not.