Sunday, August 24, 2014

Goldenrod and the Composites

When most other flowers have come and gone, this is the season for the many species of Goldenrods, their tall yellow plumes waving in the breeze.  I was watching bumblebees and two different kinds of wasps probing the flowers of a goldenrod by my driveway the other day when I became curious.  Most goldenrods contribute to the blaze of yellow you see at this time of year with an extravagant show of flowers, but the flowers themselves are small.  About how many flowers are there?  I plucked a branch--one of perhaps thirty in the cluster, and carefully counted the tightly-packed flowers on it: eighty.  If the branch I counted was fairly typical, the whole plant had 2400 flowers.  

Goldenrods (Solidago) attract bumblebees and wasps, among other insects.

Focusing on a single branch, we see dozens of things that look like flowers.

I counted 80 flower heads on a single branch.

But not so fast.  Looking closely at a few flowers, I count a dozen or so petals.  If you've looked at a lot of flowers, you realize that a great many have five petals, monocots such as lilies have three or six, mustards have four, but none have more than six petals.  Coming across a flower with a dozen petals signals us that we are NOT looking at a flower--we are looking at a cluster of flowers packed so tightly they appear as one: a flower head.  You will find this in a variety of familiar plants, from goldenrod to dandelion to aster to daisy to sunflower--all members of a single large family of flowering plants: the Composites. That means my goldenrod has about 2400 flower heads, not individual flowers.

The Composites, aka Aster Family or Asteraceae, are hugely successful in their variety.  Gleason and Cronquist's Manual of Vascular Plants of the Northeastern United States and Adjacent Canada (2nd edition) lists 147 genera with too many species for me to count, devoting 112 of its 900-odd pages to descriptions of this one family.  This success is presumably due in part to their distinctive feature: the flowers of composites are tiny things, but they are massed together in much larger flower heads.  In effect, a composite multiplies its chances of attracting pollinators by having its tiny flowers in larger, more-visible masses

Composites I noticed while walking the dogs.
(If I don't know exactly what they are, how do I know they're Composites??)

Black-eyed Susans are a familiar member of the family.

This is not the Common Dandelion (Taraxacum officinale), 
but a distant sister, Fall Dandelion (Leontodon autumnalis)

 Instead of the barbed-arrow-shape of common dandelion leaves,
fall dandelion has leaves with an outline like  some Medieval weapon.

On the other hand, fall dandelions spread their offspring on the wind, the same way common dandelion does.

 Aster, one large genus of Composites, gives its name to the whole family: Asteraceae.

Some of these flower heads, like those of dandelion and hawkweeds, simply look like huge masses of petals.  But others have flower heads that look for all the world like single flowers: a ring of  "petals" surrounding a colorful center.  That's because their flowers are differentiated into two types: tiny "disk flowers" and long, strap-like "ray flowers."  Careful examination will show that a ray flower is has its five petals joined together in a single long strap, and you can prove that it is itself an entire flower by finding its pistil--the part of the flower that accepts the pollen and makes the fruit. 

The artful devotees of this strategy form a family of flowers that includes many familiar species that brighten our gardens and colors our roadsides and fields--that, in fact, rules the early summer months.

Returning to my goldenrod.  Though made of many flowers, even the flower heads of goldenrod are tiny--perhaps 5 or 6 mm tall.  By massing these heads into even larger clusters, the goldenrod does one better: heads themselves are further massed, making a cluster that may be a foot tall and wide, creating a huge display.  Of how many flowers does this display consist?  Each tiny head is made up of even tinier flowers of both kinds: disk and ray.  The dozen-odd ray flowers surround a smaller group of disk flowers.  Suppose the typical head has 20 flowers in total.  This would make the total 20X2400=48,000 flowers on a single plant!.  And every one of them is ready and able to make a seed.  

Friday, August 22, 2014

A Week on Ponkapoag Pond

Our week at an Appalachian Mountain Club cabin on Ponkapoag Pond (only half an our from home, but very different from the city) brought a few nice surprises along with familiar sights.  This was our Second Annual stay--showing how quickly a tradition can be formed if enough of the family approve!  (Here is last years'.)

There is no potable water at AMC Ponkapoag, and the outhouses are pretty ripe at this time of the year, but even my wife loves coming here.  The cabins are available year-round for modest fees, campers often have years and generations of memories of the place, and most work is done by dedicated volunteers.  It's a bit of a community, really.  Those who enjoy society hang around the little dock at the pond's edge, while their children swim, boat or fish.  The pond is rather small and not very deep, and various water plants can make kayaking difficult in places, but it boasts a real Atlantic White Cedar Bog at the other end, and it is set in the beautiful Blue Hill Reservation.  It is a great place to enjoy fairly undisturbed forest, and socialize with others of like mind.

 A dragonfly making  a long visit to our outdoor table (shy his right rear wing)
allowed me to make use of Sidney Dunkle's Dragonfies through Binoculars.
I decided he was mostl likely a young male Eastern Pondhawk.

 I haven't figured out this lovely big fungus yet.
If it's a good edible, it would have made a whole family meal.

Walking the trail near the camp brought to light two kinds of Tick Trefoils (Desmodium)

My attempt to get a panoramic view of the pond by the camp.  
At least a dozen kayaks and canoes line the nearby shore.

My son and I kayaked to the far end of the pond on the second day, and I enjoyed the pond edge plants.

The foundation of any bog is Sphagnum, aka peat moss.
In sunny locations it can take on a "sunburnt" appearance.

A boardwalk maintained by volunteers allows egress to the entire quarter-mile distance through the bog to open water. The trees are Atlantic White Cedar, making this unusual among bogs.

 Bog Cotton (Eriophorum virginicum) is related to neither cotton nor grass;
it is a distinctive plant I've never seen outside of a bog.
Red-rimmed leaves of Round-leaved Sundew (Drosera rotundifolia)mark a palm-sized 'insectivorous" plant characteristic of nutrient-deprived places like bogs.  Sticky hairs trap passing insects, which are captured not for food, but really for their nitrogen "fertilizer" potential.

 The parasitic vine Dodder (Cuscuta) is a plant that cannot make its own food
--its yellow color showing its deficiency in chlorophyll.  Instead it twines around other plants,
 absorbing nutrition through peg-like haustoria that are just visible in the photo. 

Open water at the end of the boardwalk.  Its possible to land a kayak there, 
but the landward end of the boardwalk is a nice two-mile stroll through forest.

Once off the boardwalk, I took the time to admire a cattail marsh
that has so far escaped invasion by Phragmites reed.

Birds playing aerobatic chase over the marsh reminded me of chimney swifts at home,
but turned out (after many attempts to photograph) I think to be Bank Swallows.

One rainy day meant our only meal indoors.

 The last day I rose early to take in the dawn and early morning.
I sat quietly for half an hour with this sky overhead.

I had seen enough dead trees without their bark to know that the grain often spirals,
but I'd never seen bark that peeled off in a spiral.

 A tiny lichen & moss garden that caught my eye as we walked around the last day.
The branching lichen on the left is (confusingly) called Reindeer Moss, though it is no plant at all.

 Boulders--many enormous--abound around the pond, reminders of glaciers that receded 12,000 years ago.
But some have now become decorated with plants such as this Common Polypody (Polypodium vulgare).

The afternoon sun breaks through and glows on the far end of the pond.

Tuesday, August 5, 2014

Waiting for Fruit

On my neighborhood walks I find myself looking down at strategic moments for fallen fruit.  Tracking the seasonal changes in different trees (aka phenology), involves noting the dates of first leafing out, flowering, fruiting, and maturing and falling of fruits and seeds, then coloring of leaves, and finally leaf fall.  When I can, I check on fruit by looking at the trees themselves, but sometimes this doesn't work.  Some of the trees are simply too tall, with too few lower branches to see clearly.  In some cases, trees bear no fruit, which can lead to some frustration while staring aloft with binoculars.  The lack of flowers or fruit in the youngish pignut hickory in the woods would have kept me guessing for a long time, if not for the flowering and fruiting of a larger neighbor with low branches. 

I was embarrassed to miss a lot of these changes in the big white ash in my yard: it leafed out late in the spring, and I waited a long time for it to show flowers, but saw none.  Only later looking on line did I discover that white ash leafs out and flowers simultaneously--the flowers are small, and the tree very tall with no low branches.  Since all I can see from the ground is leaves, I can only assume it flowered and the fruit is maturing; I will watch for the slender, one-winged fruit on the ground in fall.  

 Crown of sixty-odd-foot white ash catches the sun's last rays.  Other photos are close-ups of the crown, most taken on a tripod, at zoom of 3.6X, and uploaded at full resolution.  Can you find any of the fruits?

I've even attempted to get a look at the ash by telescope: here I'm shooting through
the eyepiece of a four-inch reflecting telescope.  Still nothing.

Several kinds of oaks do this to me routinely.  Female oak flowers are in small and and inconspicuous clusters, but fortunately the male are in drooping catkins that are more visible.  On the other hand, an acorn an inch or less across is hard to spot in a fifty-foot tree.  There are enough scarlet oaks that some have low enough branches for me to watch, but red oaks are much scarcer, and I know of only one indisputable black oak on my neighborhood ramblings.  Both white oaks in my back yard are tall: more staring at the ground.

Red oaks I watch.  The last, on the mound, is actually a cluster of several separate trees;
two of these have small branches at eye level, but these branches did not bear flowers.

The only black oak I've seen in the neighborhood has some low branches, but I would have to 
trespass to get a really good look.  One day soon I'll talk to the landowner.

I was delighted to discover, early in the summer after high winds, a fallen twig that proved that a sugar maple I watch was female; I had concluded that all the sugar maples in my neighborhood were male, since I'd seen no keys (double-winged fruits).  Their invisibly sparse fruiting contrasts with the prolific Norway maples, which often bear so heavily that the tree changes color as the keys mature.  So far, the only way I know there are probably still keys up there somewhere is finding one fallen on the ground, the embryos killed by insects.  Confusing things further, it seems that sugar maples are sometimes bisexual.  So there may be more "females" yet, though with few enough keys that they have not yet declared themselves to me.

Fallen sugar maple twig.  The keys have an almost square shape,
unlike the nearly straight keys of Norway maples, or the V-shaped keys of red maples.

Aha! must still be some up there somewhere.

Most of the fallen keys I've encountered lately have had both embryos eaten by insects, 
but this one seems to have one seed intact.  I wonder if it would grow?

For all these reasons, I spend as much or more time looking at the ground under such trees as looking at the trees themselves.