Sunday, November 28, 2010

Winter Twigs


The bare twigs of woody plants are quite mysterious to many people.  Without the benefit of leaves or flowers, they can be at a loss to figure out what plant stands bare before them.   But when you really look at the winter twigs of woody plants, you can see a lot more differences than you might have thought.  Here, buds swollen with the promise of spring growth already, is Aesculus pavia, the red buckeye that hummingbirds love so much:
Aesculus pavia
And here is a shrub that looks all but dead in the wintertime, no sign whatsoever of next year’s growth.  This is Calycanthus floridus, the marvelously aromatic sweetshrub or Carolina allspice.

Calycanthus floridus

 
 
If you’re interested in identifying plants in the winter, there are some basic clues that can help narrow the possibilities of what the plant might be.  I’ll cover a few of them just to help take some of the mystery out of the process.
  • Leaf arrangement: even when the leaves are gone, you can see the leaf scars of where they were. Are they opposite one another along the stem or arranged in an alternate pattern?  If you can’t see the leaf scars, remember that branches themselves were once leaves - how are the branches arranged? Focus if possible on the “twigs” – the most recent year’s woody growth.  Be careful to check in multiple places because one twig might have fallen off, making the arrangement appear to be alternate.  Both the buckeye and the sweetshrub have opposite leaves (see above pictures), and here is a Viburnum
    branch, showing off perfectly opposite twig arrangement:
Viburnum acerifolium
  • Leaves on the ground can sometimes provide a clue: this is not the most reliable approach, especially if there are a lot of different plants around, but it might give you a few things to start looking at if you recognize the leaves.  For example, you might find maple leaves, oak leaves and sassafras leaves on the ground.  But when you look at the plant in question, you notice it has opposite twig arrangement.  Of those 3 choices, maple is the only one that has oppositely arranged leaves and twigs. 

  • Leaf and bloom buds already formed can be familiar: for some people, memory is all they need to recognize a plant without leaves. Here is a picture of one of my favorite bare twig plants, American beech (Fagus grandifolia):  
Fagus grandifolia
I love the beech's distinctive cigar-shaped leaf buds with tips so pointed they look like they could stab you and draw blood.  There are other trees with pointy leaf buds, however, that could confuse you. 

Amelanchier sp.


For example, Serviceberry (Amelanchier spp.) has them, but the buds are not as long,  not uniform in shape and they have the tiniest bit of “fluff” at the tip of the bud.  If you have a good memory, you can learn to recognize what you’ve seen and identified before.

  • Leaf scars and bundle scars: some plants have very noticeable and unique leaf scars.  Leaf scars are the spots left behind when the leaf fell off.  Bundle scars can be found inside the leaf scar – they reflect where vascular bundles connected to the leaf and they can be very unique in number and in the shape of them.  You can find a great picture of a leaf scar that contains 3 bundle scars at this website (the plant is Black Gum, Nyssa sylvatica).
  • Bark characteristics: some bark is very distinctive and you can learn to recognize some trees by their bark.  You can then verify your identification with another characteristic as I mentioned before.  For example, Cornus florida (Flowering dogwood) has rather unique bark and it also has twigs that are opposite one another.  Recognize the bark and then verify it with the twigs.  While Cornus florida also has very distinctive bloom buds, not all trees are in a position to form bloom buds (for example, the tree may be in deep shade):
Cornus florida
  • Remaining fruits/seeds left clinging to the twigs: sometimes you can find fruit or seeds clinging to the branches.  Some fruit is in the form of a capsule that may open to release seed, leaving the capsule behind.  Here is a picture of the capsule on an azalea (Rhododendron sp.), you can see both open (ripe) capsules and those which are not yet ripe.  Knowing the form of the fruit might help you distinguish one plant from another.
Rhododendron sp. (Azalea)
Here is another example of two plants that look very similar if you are just examining the buds on the most recent growth.  On the left is the twig of an Oak (Quercus) and on the right is a twig of an azalea (Rhododendron).  By further examining other features (the slightly flakey bark on the azalea is often enough to distinguish the two), you can get a little closer to the right identification or at least eliminate a possibility or two.
Quercus sp.

Rhododendron sp. (Azalea)
 

I’ve only scratched the surface of a very deep topic.  For those of you that would really like the tools to identify winter twigs, I suggest you get a 10x hand lens and a good key.  If you’re in the Southeastern US, I recommend “Woody Plants of the Southeastern United States: A Winter Guide” by Ron Lance.  In addition to very detailed keys, the book has descriptions of each plant according to winter characteristics and most plants have detailed drawings of the twigs themselves (and a good glossary too).

So don’t be intimidated by those bare branches – get out there and figure it out.  I suggest starting with a tree that you already know and examining the twigs and winter features.  Good luck!

 

2 comments:

  1. Ellen, great post! Your photos are crystal clear and really illuminate the subject of winter ID. Hope tons of people read this; they will definitely be inspired to become woods detectives!

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  2. Very interesting article, Ellen! I learned a lot about twigs and buds and tree bark! Photos are great, too! I'm bookmarking this to study again!

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