White Ash

I became acquainted with my first ash tree--a white ash--as a new homeowner nineteen years ago.  The home inventory by a proud, new member of the landed class who was trained in botany would naturally include plants, and I not only mapped out the various grasses and sedges that clothed the backyard, but also noted the larger trees there and in the little patch of scrubby woodland behind it.  The tall, willowy white ash stands at the border between yard and wood. 

For years, this was a nodding acquaintanceship.  I would sometimes remember to look her way in passing, paying special attention whenever a stiff, gusty wind encouraged her to sway majestically.  But for years I didn't even know ashes had gender, much less that this ash was female.

 Fall colors; our tree glowing in late afternoon sun.

The relationship became a little more serious a few years ago when I decided to make my dog-walks around the neighborhood into natural history walks as well.  I found white ash to be fairly common in the neighborhood.  I watched their leaves bronze in the fall, and waited to see them flower in spring.  In fall three years ago I worried as the tree dropped much of her foliage prematurely in our local drought, looking terrible by the time the drought ended.  That first year I trained binoculars on the high limbs of my tree as it took its own sweet time leafing out, but never saw a single flower. 

Soon after, I became aware of the imminent arrival of the Emerald Ash Borer, against which American ash trees have no resistance.  This alien invasive beetle first appeared near Detroit in 2002--probably accidentally introduced from Asia in packing materials.  It has since spread to about half the area of the US, reaching within a dozen or so miles of Brockton, MA as of two years ago.  The boring of the beetle larvae beneath the bark effectively girdles the trees, and kills them.  Several species of ash are probably doomed nationwide.  (The regular treatments with various insecticides that can save individual trees would be too expensive and labor-intensive to save wild populations.)  Volunteers are monitoring for its arrival--an effort I helped with two summers ago as a "wasp watcher." 

All this time I had been taming my impulse to learn mainly by reading or Googling; I observed first.  But I knew very little about what I should look for, and when.  So when the first spring's observations were fruitless, I did a little research.  Ash is dioecious, having male and female flowers on separate trees.  Male flowers have a profusion of purple stamens, while female flowers are tiny, and borne in large but spindly branching clusters.  The flowers emerge just before the leaves, so I may have looked for them too late.  Even without the evidence of flowers, I strongly suspected mine was female: the woods behind were dotted with ash saplings, yet I knew of no other mature trees very nearby. 

Early spring.

Emergence of pollen-bearing stamens.

Male tree in flower and leafing-out.

Surveying the ash trees of the neighborhood the following spring, I gradually discovered that nearly all were male; the few that did not have male flowers did not appear to flower at all.  (My own ash was one of these, and only in the fall did I find a few winged seeds on the ground that could only have been her meager offspring.)   But taking a new walking route in summer I suddenly came upon an ash tree loaded with winged fruit--seeming singlehandedly to make up for the backwardness of her sisters. 

Treasure: the winged seeds of white ash.

Last year this fecund tree was disappointingly devoid of flowers--but elsewhere I discovered another wizened, gnarled street tree that was bearing heavily. 

This year I watched again, tracking more ash trees than ever.  Sure enough, nearly all produced male flowers, but finally most trees that had gone two years without visible flowers now sported the wispy tree-like inflorescences of female flowers.  Even my tree, most backward of all, has a handful of inflorescences in the high branches in one place--only clearly visible using a telescope.  But that first fecund ash has announced she is still on vacation. 

Female flowers and developing fruits on May 11th, 16th and 20th.

Female flowers and leafing-out.

White Ash is only one of the two-dozen-odd tree species I follow on my walks.  Although often graceful at a distance, the twigs are rather ugly, thick, lumpy things; cartoon twigs drawn by a bad artist.  The male flowers look like they belong on another planet; beginning as globular tufts purple stamens, they rapidly morph into untidy fountains.  Tiny female flowers borne in spindly clusters are nearly invisible at any great distance, and only two of the female trees have flowers low enough to be readily seen without binoculars.  The bark is nothing much to look at, most resembling the vertically ridged bark of the Norway maple that is everywhere in cities and suburbs in the northeast.

But white ash is still a mystery: why so few females in the neighborhood, and why do they produce prolifically one year, and sometimes go reproductively dormant the next?

The specter of a metallic green beetle still hangs over all ashes.  And behind my eagerness to see the trees reproduce is a dim hope that, with enough genetic diversity,  a few of the ashes will survive the beetle attacks--either having chemical defenses that deter them, or healing the wounds they make rapidly enough keep leaves and roots connected. 

On the Verge of Spring

The advance guard of spring—first the silver maples and then the red maples and quaking aspens—seem to have got out front alone.  I had thought spring was arriving a full month early, but it seems the other trees paid no attention to these three, and have been adhering to their own, more cautious, calendars.  The demonstrative Norway maples began to bloom in earnest this week, casting a green light over city and suburb, while the shy sugar maples are opening delicate green flowers here and there.  Paper birch catkins stiff and contracted all winter are stretching out and dangling as they prepare to drop loads of pollen, and some are beginning to leaf out, as well.  Ashes—the males, at least—are just beginning to bloom, and black oaks have buds poised to display their long, dangling flower clusters from every twig.  All in all, so many things are about to pop that we are on the verge of “spring”—the beginning of the growing season.  

Buds of black oak (Quercus velutina) breaking over a week or so

to unleash a fountain of flowers and leaves.

Other black oaks around the neighborhood getting ready to pop.

 White oaks (Quercus alba) won't be far behind.

With the foliage coming in, spotting the morning musical performers

like this black-capped chickadee is about to get much harder.

Thr little pussy willow at the high school is nearly finished.  Here it was a couple of weeks ago.

The green you've already seen is mostly Norway maple (Acer psuedoplatanus). 

It has at least a week's head-start over the earliest oaks.

 

Norway maple leafing-out.

White ash (Fraxinus americana) is beginning to flower, but so far only the males.

Ash-leaved maple (Acer negundo) is a rather strange tree

that flowers differently from other maples, dangling long, unruly red stamens.

These are around an abandoned parking lot by Palmer Avenue

Paper birch (like other birches) have their flowers ready to go in tough, compact catkins in fall,  

In spring, these relax, lengthen, and begin dropping pollen just before the leaves emerge.

I only discovered that we have sassafras (Sassafras albidum) at West Middle School

a few weeks ago, just before the flowers emerged.

Larch, or tamarack (Larix laricina) is gradually lengthening its tufts of soft, green needles.

The larches at the VA must be planted, they are so far from their sub-arctic home.

 Sugar maple (Acer saccharum) is not as demonstrative as its foreign cousin, Norway maple.  The flowers emerge here and their, small and demure, and are gradually hidden by expanding leaves.

Silver maple (Acer saccharinum) got the jump on everyone,

and had expanding leaves almost before any other buds were broken.

Flowering dogwood (Cornus florida) is preparing to justify its name.

Leaves of the one witchhazel bush I know in the neighborhood are beginning to unfold.

Quaking aspen (Populus tremuloides) has long since finished flowering,

but is only now beginning to spread its leaves.

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