Characteristics for Identifying Trees – Catkins

Well, today is the first day of spring. We’re expecting another inch or so of snow tonight. Will it ever end? Well, when it does, the first signs of spring may not be leaves emerging from trees, but the flowers of wind pollinated trees. At Dennis Panu Arborist, we use many tree characteristics to identify trees, but, botanically speaking, the most accurate way to identify trees to species is through their flowers. In the spring, several plant families in New England produce their flowers in structures called catkins: small clusters of tiny flowers bearing a resemblance to a cat’s tail. (“Catkin” comes from an old Dutch word for “kitten.”)

Most people think of flowers as being colorful and showy. While this is true when flowers need to attract pollinators like birds or insects, trees with catkins are typically wind-pollinated. Each catkin is made up of many tiny inconspicuous flowers. Most catkins contain male flowers, producing prodigious amounts of pollen, but some trees also have female catkins. In order to facilitate pollen distribution, catkins often appear early in the spring before the tree produces leaves which would block the wind.

If you live in Massachusetts or Connecticut, keep an eye out for trees from these families as they produce flowers in the spring:

• Birch family (Betulaceae)
Trees in this family include birch, hazelnut and hornbeam. Look for the pendulous male catkins dangling in the wind early in the spring. Birch family trees also have their female flowers in catkins, which are much smaller then the male catkins and fixed on the branch. (An exception is hazelnut; the female flowers occur singly on the branch to accommodate the large nuts.) Betulaceae trees are monoecious (“one house”), meaning that male and female flowers occur on the same tree. The species of birch can often be determined by the number of catkins in each cluster. Here are some photos of birch catkins.

• Willow family (Salicaceae)
Including willow, cottonwood and poplar, trees in this family are dioecious (“two houses”), meaning that male and female catkins appear on separate trees. It can be difficult to tell the tiny male and female flowers apart, but an arborist can make the distinction. The fuzzy “pussy willow” you see in flower arrangements is a classic example of this family’s catkins. Also, the drifts of snowy seed pods floating through the air in spring are a sure sign that a female Salicaceae tree is nearby.

• Oak and beech family (Fagaceae)
Everyone recognizes the acorns produced by oaks (or, less commonly, beech nuts), but keep an eye out for these trees’ flowers. Oaks and beeches produce hanging male catkins for wind pollination. Female flowers are not in catkins, however, but occur singly or in pairs in the leaf axils (where the leaf meets the main branch). Fagaceae trees are monoecious, with both male and female flowers on the same tree.

For help identifying trees on your Massachusetts or Connecticut property, or for other tree care service questions, contact Dennis Panu Arborist today.

Veteran and Wolf Trees

There is more and more discussion among arborists regarding preserving “old” trees.  Many are concerned that these “over-mature” trees, with their dead branches and open cavities, pose a threat to people nearby.  Others argue that these “veteran trees” as they are referred to in Europe, or “wolf trees” in the American lexicon, provide valuable and irreplaceable ecological benefits.  We are talking about 100 to 300 hundred and even 500 year old trees here.  Everyone recognizes the antiquity of the redwoods and bristle cone pines out west, but many of these veteran, or wolf trees, reside right here with us in New England, some outdating the birth of our nation.   We need to learn to recognize these trees for what they are and not as just some old tree that should be removed.  Here is an interesting article about “wolf trees” in our forests, but you should recognize that many of these trees also exist in our own back yards.  Before you decide to just kill that old tree on your property, you should consult with an ASCA Consulting Arborist to discuss your options and just maybe save hundreds of years worth of history and a habitat that can’t be recreated for centuries to come.

Wolf Trees: Elders of the Eastern Forest

What’s Killing All the Spruce Trees?

You may have noticed that many the spruce trees in our area of southern New England have been dying lately.  The cause is a fungal disease called Rhizosphaera needle cast.  Like most needle cast diseases, Rhizosphaera infects the newly emerging needles of its host trees from older needles infected the previous year.  The newly infected needles will grow normally through the current growing season and will not show signs of infection until the fungus matures to its spore producing stage, usually late winter or early spring of the following year, but sometimes as early as late fall of the current growing season.  As you can see in the photograph below, the disease typically affects the lower portions of the tree first and progresses farther up the tree in subsequent years until the tree dies.

Tree in Southbridge, MA infected with Rhizosphaera needle cast.

This infected tree in Southbridge, MA shows the typical progression of Rhizosphaera needle cast from the lower to the upper branches.

Not all spruce trees are equally susceptible to infection by Rhizosphaera.  Colorado spruce (Picea pungens) is most susceptible.  White spruce (Picea glauca) is somewhat susceptible and Norway spruce (Picea abies) very resistant to infection.  Trees stressed by drought, poor cultural practices are more susceptible than healthy, vigorous trees.


Trees infected with Rhizosphaera can be effectively treated with well timed, preventive fungicide applications if the disease is caught early enough.  Spruce trees typically retain three to five years worth of older needles that they need to photosynthesize enough food to maintain growth.  Rhizosphaera kills the trees by causing these older needles to fall prematurely, slowly starving the tree.  It may take several years of treatment to regenerate a full compliment of needles until the tree looks full and healthy again.

To learn more about Rhizosphaera needle cast, contact us or visit these websites:

CT.Gov Fact Sheet on Rhizosphaera Needlecast

Invasive Plants in Naturalized Areas

IMAG0079Invasive plant species are a problem that can have a serious impact on our local ecosystems.  The Massachusetts Invasive Plant Advisory Group [MIPAG] defines invasive plants as “non-native species that have spread into native or minimally managed plant systems in Massachusetts, causing economic or environmental harm by developing self-sustaining populations and becoming dominant and/or disruptive to those systems.”    According to the New England Wild Flower Society, “seventy-nine species [of invasive plants] cost the U.S. economy more than $97 billion annually in lost crops, failed recovery efforts for endangered species, and control efforts. Invasive species have contributed to the decline of 42% of U.S. endangered and threatened species; for 18% of U.S. endangered or threatened species, invasives are the main cause of decline.”

Invasive plants decrease biodiversity and displace native species that wildlife depend upon for food and cover.  For example, bush honeysuckle (Lonicera s.pp.) creates dense stands that exclude native plant species.  The fruits, produced from mid-summer through early fall, are very attractive to birds.  While the fruits are rich in carbohydrates, they lack the fat and nutrient content to sustain migrating birds on their long journeys south; they are essentially junk food for birds.  Because the dense stands of honeysuckle exclude the nutritious native plants, they become the dominant fodder for migrating birds at a time when they need to foraging on nutritious food for their trip south the most.

In most cases, it is not practical to completely eliminate invasive plants from your community, but you can create pockets of invasive free areas on your own property.  First, identify invasives on your property.  Spring and fall are good times to look for invasives; most of the understory invasive shrubs leaf out first in the spring and drop their leaves last.

Putnam Thompson Woodstock Danielson Killingly Plainfield Union

The first flush of green in this North Oxford, MA woodlot is from Japanese barberry (Berberis thunbergii). In addition to all the other negative aspects of invasive plants, Barberry is implicated in the spread of Lyme Disease; The dense thickets formed by these thorny plants protect white-footed deer mice, the main host for the disease-vectoring black legged or deer tick, from predators.

Of course there are many other invasive plant species you may want to familiarize yourself with and explore the various options for controlling them, including mechanical methods such as hand pulling them or chemical controls.  Here are just a few of the many websites you can visit to learn more about invasive plants and how to control them:

Massachusetts Invasive Plant Advisory   Group

Audubon Connecticut

New England Wild Flower Society

RI Invasive Species Council

The Invasive Plant Atlas of New England’s (IPANE)

Pennsylvania DCNR

This Winter’s Cold Weather May Help Control Some Insect Pests

Well, I for one have had enough of the 2013-2014 winter season.  Its March 13 and its snowing.  Again.  But this brutally cold winter season may have some beneficial side effects.  In a March 2, 2014 Worcester Sunday Telegram report, University of Massachusetts-Amherst Professor Joseph Elkinton notes that the extreme cold, down to 15 degrees below zero F in the Amherst area, will likely result in a large die-off of the Hemlock Wooly Adelgid, a non-native invasive insect pest that has devastated our hemlock forests and is a serious pest of hemlocks in our landscapes.  In the same article, Kenneth Gooch, Forest Health Program supervisor for the Department of Conservation and Recreation is optimistic, noting that the last time we had temperatures this cold, adelgid mortality reached 80%.  Keep in mind, however, that the reprieve is temporary.  The adelgids that do survive will eventually rebound, and may produce offspring genetically more resistant to cold temperatures.  And while I did not experience temperatures as cold as Professor Elkinton reported here in southern Worcester County or Windham County, we did have several nights of below zero temperatures, and some adelgid mortality results at temperatures as “warm” as 5 degrees F.

As much as I hate to admit it, we have had it easy here in New England.   The folks in the Midwest really got frosted and the south was exceptionally cold.  But again, more potential good news.  The Week magazine reports that the cold has killed 80% of the Emerald Ash Borer, another non-native invasive insect that has killed tens of millions of ash trees in the Midwest and has now been found in New Haven County, CT, western Massachusetts and North Andover, MA, and  New Hampshire.  The Week  also reports that large percentages of Gypsy Moths, Hemlock Wooly Adelgid, Corn Earworm, and the citrus destroying Cottony Cushion Scale have been killed off by the cold.

I don’t expect this to be the end of our problems with these invasive pests, but its comforting to know that some good can come from our having to endure the winter of 2013-2014.


I came across this red oak tree with a huge burl on it in Oxford, MA last fall.

Burls have always fascinated me.  Burls usually form on a tree’s trunk but can grow on limbs as well.  We know that burls are the result of unchecked, disorganized growth creating wildly contorted grain and a “bird’s eye” effect caused by aborted adventitious buds, but no one really knows why they form.  Burls should not be confused with cankers and galls, which are usually caused by pathogens or insects.  Burls always have bark on them and only rarely have sprouts; internally they are composed of all sound wood.  Cankers and galls often have internal bark and decay initiated by the agents that cause them and may have sprouts that grow and die as they get larger.

A Tree in Webster, MA Removed Because of Root Rot

Here is an interesting tree we recently removed in Webster, MA.  The owner was concerned about the large split that had propagated up the lower trunk in the photo below.


The pronounced swelling at the base of the tree caught my attention.  This is often a sign of a root rot progressing up into the lower trunk.  The tree “senses” the weakness in its trunk and adds extra growth to that area to shore itself up.  You can see in the photo of the overturned stump after we cut the tree down, where the root rot has decayed the center of the tree and where the tree added new sound wood around the perimeter of the stump in an attempt to preserve itself. Unfortunately, the decay had progressed about ten feet up into the trunk, leading to the crack opening up in a wind event, requiring the removal of the tree.


Planning Your 2014 Fruit Crop

Well, its snowing AGAIN here in Thompson, CT.  Cabin fever is setting in.  But for those of you planning your fruit crops for the coming year, there is hope.  Here is a link to the UMass Extension’s Cold Spring Orchard.  and the Fruit Adviser web page  You’ll find useful information information on everything from selecting good apple varieties to plant in New England to how to prune your raspberries.  So start boning up; spring will be here before you know it!

Why Don’t Trees Freeze?

Last night was the coldest night we have had here in Connecticut in about 20 years; it got down to 8 degrees below zero Farenheit.  That reminded me of a question often asked of me:  Why doesn’t the water in the trees freeze and cause them to burst open like frozen pipes?

Water is stored in trees in two ways; as free water and water stored molecularly.  Free water in the xylem vessels and tracheids that would freeze and burst those cells is purged from the tree.  The remaining water in the tree is stored as individual or small groups of molecules bound to other molecules in the trees’ cells.  Stored that way, the water molecules cannot arrange themselves into the expanding crystal lattice that causes pipes to burst.

Characteristics for Identifying Trees – Twigs

We use many characteristics to identify trees such as leaves, buds, bark, form, and even the diseases they get and where they are located.

This time of year, with no leaves on most trees, I depend mostly on the twigs, buds, and bark of the tree.  Some trees are easily identified from afar by their bark, such as shagbark hickory (Carya ovata).  For other, more difficult to identify species, I begin by looking at the twigs.  The most important characteristic of the twigs to note is how the buds or secondary branches are arranged on them.  Most of the trees in my region have the buds emerging alternately on the twig.  That is, one bud will emerge on the left side of the twig, then the next will emerge on the right side, continuing along the twig.  This arrangement is usually modified by the opposite pattern on emergence spiraling up the twig, so that looking at the twig on end, the bud placement resembles a spiral staircase.  Oaks, elms and cherries are common examples of this arrangement.

Alternate Branching Habit

Less common is the opposite branching habit, where two buds will emerge opposite each other on the twig.  Again, this pattern is usually modified such that each successive pair of buds emerge perpendicular to the previous pair. This arrangement is common on viburnums, maples, dogwoods, and ash trees.  Opposite branching habit is a particularly useful characteristic to note because relatively few trees bear their branches oppositely.

Opposite Branching Habit

A third branching habit is the whorl.  A whorl is where three or more buds emerge together on the twig.  Trees bearing the whorled habit are even fewer that opposite branched trees.  Catalpa is a common example.  Pines, spruces, and firs are also examples of trees with a whorled habit.

Whorled Branch Habit

Once you have identified the branching habit of the tree, the next step is to examine the buds.  I will talk more about the buds and other characteristics in following posts.