If you see acorns on the ground, look up: it's probably Red Oak

The local oaks have begun dropping their acorns, and stately Northern Red Oak (Quercus rubra) is first.  Since oaks are rather tricky things to destinguish, it's handy to be able to use this time to pick them out of the crowd.

The many species of oaks come in two basic flavors (subgenera or "sections") here in eastern North America: those with round-lobed leaves, and acorns that mature in one growing season and are more sweet-tasting with acorn cups hairless inside, called the "white oak group"*; and those with bristle-lobed leaves, and bitter acorns that need two growing seasons to mature and have cups hairy on the inside, called the "red oak group." 

Red Oak has leaves that are generally "more leaf than hole," while roughly-similar black, scarlet and pin oaks are often "more hole than leaf."  In Red Oak the acorn cap covers only the end of the nut, whereas other local trees in its group have caps that surround much more.  (White Oak, which will begin dropping acorns soon, has nuts with a similar "beret," but these are easy to distinguish, since that beret has a very bumpy surface, unlike the nearly smooth caps of Red Oak.)

Red Oak branchlet with a mature acorn begun last spring, and tiny acorns (looking a bit like buds) in pairs in the axil of each leaf.  (A bite mark on the end shows a bad-mannered squirrel cut it down.)

 

 

If reproduction is a chancy business in the best of circumstances, it is much more so for a city tree.  Car tires and shoe soles end the careers of  many oak babies once they've fallen.

Northern Red Oak is an important forest tree throughout the eastern US, and its acorns--bitter though they are--are food for many animals.  It is the only one of its local sibling species that has bark with stripes that run all the way down the trunk--even on large trees. 


*This also includes Southern Live Oak, the famous deep South tree iconically Spanish moss covered.  It has entire (unlobed) leaves that are green almost year-round.  (If you want to see Live Oak here, visit Old Ironsides in Boston Harbor: it is framed and planked with its tough, dense wood.)

Counting Things

I once heard it said that a scientist who didn't know what to do next would count things.  There's no telling what might turn up in the data!  But the saying needs to be taken with a grain of salt: scientists count (measure) things because quantitative (numerical) data has several advantages over qualitative data: it's more exact and less open to misinterpretation, it's open to powerful statistical analyses, and it can be applied more closely to real-world issues.  I'd guess it's been over a century since science could be done without quantitative data.

I long ago noticed that the samaras (winged seeds*) that fall from sugar maple trees often have bite marks in them.  Many of these have been eaten, leaving an empty shell.  A few minutes' research brought forth the likeliest culprit: squirrels.  The gray squirrel, far from being an acorn specialist, is actually broadly omnivorous, eating a variety of nuts and berries, buds and bark, and not passing up an undefended, nestling bird, either.  The menu specifically includes maple samaras, buds and bark.  How serious is the damage to maple reproduction?  A little half-vast science would provide a clue.

On my walks over the last few days I brought plastic bags and a sharpie marker.  Under three different trees varying distances apart I picked up fistfuls of fallen samaras and put them into labeled bags.  Under a particular tree I've been watching I collected three bags--to get an idea how much random variation there was.  Then home I went to count things. 

 

Science is messy!  Or it that just me?

 I saved the samaras that had at least one intact seed.  Hmm--if half of them germinate,

I only need an acre or so of land to plant them all!

Probably the hardest job doing this sort of science is deciding what to count.  For example, if I decided that every samara was either eaten (seed gone) or alive, what about those I'd seen with a bit mark that might or might not be dead? or the samaras damaged by insects? or those I simply couldn' decide on?  So first I emptied a bag on the kitchen table, pawed through it, and decided on categories.  Even, then, I can't pretend there weren't judgement calls, and my judgement may well have changed as I worked.  For this and other reasons (chiefly about my sampling method and the small number of trees I looked at), I call this "half-vast science."**  Nevertheless, I think I learned some things. 

There was variability between samples taken from under the same tree, but that was probably because of where the samples came from: the two that were alike were seeds that had fallen in the street, rather than on the lawn.  

Less than half of the seeds were intact in any sample, and it was more typically about one-quarter.  

There was very little insect damage: the enemy of sugar maple (at least here in the 'burbs) is the squirrel.  Period!***  

+++++++++++++++++++++++++

Oh, did I forget to mention that THE SUGAR MAPLES ARE HERE!  I noticed samaras falling from the first one in the neighborhood at the end of July, but more trees became involved and the pace really picked up in the last two weeks.  I guess we're now in the middle of it.

Sugar maples are easy to tell by their samaras.  When still joined together, samaras appear squared-off, with plump, rounded seeds.  The only other maple that might be shedding samaras right now is the common (invasive alien) Norway maple, with its nearly straight samaras with flattened seeds.

One of the sugar maples I collected samaras under.  Majestic tree!

Sugar maple samaras have plump seeds and sharply-angled wings, while Norway maples 

(few of which have yet dropped many samaras) are larger, have flat seeds, and wings nearly in line.  (Image below from www.farfromloam.wordpress.com)

Sugar maple is uncommon in southern New England, but is commonly planted as a yard tree here in the city.  It is the same tree of northern New England forests whose sap, boiled down to about 1/40th its original volume, makes maple syrup.  In recent years it has become harder for New Englanders who "tap" the sugar maple to get enough sap to make the work profitable, since the necessary conditions (days reaching about 45 degrees F with nights well below freezing, ending with leaf bud break) have been shortened, probably by climate change.

Even if it is planted, it's nice to have native maples in our yards and by out streets. 


*Really, fruit: the actual seed is inside the samara.
**aka pretty good middle school science fair project.
***Automobiles are another danger here in the city: many samaras, acorns, etc are ground to mush beneath tires.

Spring 4b

I spent a lot of time in Warwick, RI during my father's last illness, and would go walking with my camera to stretch my legs.  Warwick--unlike land-locked Brockton--is coastal, and my parents live on a peninsula that extends a mile into Narragansett Bay.  All but the first five photos were shot there.  None are plants I follow closely.

Cinquefoil (Potentilla), bayberry (Myrica pennsylvanica), 

and oriental bittersweet (Celastrus orbiculatus) in flower on May30th.

 Silverberry finishing blooming and fruits forming on May 30th.

Elm shedding fruit on June 5th.  I knew to look up when I saw

the half-inch seeds like fried eggs on the pavement.

 

Sycamore maple (Acer psudoplatanus) near my parents house in RI was a discovery.  I am now watching more maples (red, silver, Norway, ash-leaved and sycamore) than any other genus.

The leaves are shaped and proportioned like Norway maple,

but are stouter, more strongly-veined, and toothed.

Alone among the maples I know, sycamore maple often produces samaras

in threes, instead of the more common twos.

Mulberry (Morus) with maturing fruits on June 5th.  Poison ivy (Toxicodendron radicans), black locust (Robinia psuedoacacia), oriental bittersweet (Celastrus orbiculatus), great rhododendron (Rhododendron maximum), blackberry (Rubus allegheniensis), and beach rose (Rosa rugosa) blooming on June 5th. 

Morus (maybe alba?)

The small white flowers will be followed by white berries popular with birds. But don't forget

that all parts of the plant have the oil urushiol that most people are strongly allergic to!

 

Black locust is a good news/bad news tree: in the bean family, it harbors bacteria that enrich 

the soil with nitrogen; but it also drops thorny branches that can be (literally) a pain to clean up.

These tiny white flowers will give way to yellow fruit that split in fall to reveal

bright orange seeds.  Too bad bittersweet is such a vicious alien invasive!

Great rhododendron is both a native, and a popular cultivated shrub.

  If you find blackberry-like fruit on a thorny shrub

with 3-part leaves in June, they're yours to eat!

This is the rose you find in thickets above the high beach.

Their appearance and fragrance whisper of summer beach season.

Mountain laurel, in the same family (heath family) as rhododendron,

also shares its character as a native that is popular in cultivation. 

It is preparing to bloom on June 5th, blooming on the 9th.

The shrub Arrowwood (Viburnum recognatum) 

was reputed valuable in making arrow shafts. June 10th.

 

Berries of elderberry (Sambucus canadensis) are supposed to make a nice wine. 6/19

 Yarrow or milfoil (Achillea millifolium) is a common alien roadside wildflower.  6/19

Since it is now the end of June and high summer, this will be the last of my "Spring" posts.