Twigology

Learning to identify woody plants by their bare twigs is a very useful skill. Despite our recent warm months, my region is still composed of woody plants that are deciduous (meaning they drop their leaves in the winter). Having bare branches doesn’t mean that I have to wait until spring to identify any mystery plants that I find on hikes or approved plant rescues. I just employ my “twigology” skills to figure it out.

Aesculus twig; opposite leaf arrangement

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.  Here are a few of the things to consider:

Leaf arrangement: even when the leaves are gone, you can see the leaf scars of where they were, plus there are buds for the new leaves.  Are they opposite one another along the stem or are they 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.  Most plants have alternate arrangement, making those with opposite arrangement part of a more limited group. Here is a buckeye (Aesculus) branch, showing off perfectly opposite leaf arrangement with a terminal bud on top.

Old leaves: 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 arrangement.  Of those 3 choices, maple is the only one that has oppositely arranged leaves and twigs.

American beech (Fagus grandifolia)

Memory: Leaf and bloom buds already formed can be familiar; for some people, memory is all they need to recognize a plant without leaves. Bloom buds on flowering dogwood (Cornus florida) are familiar to many people. Here is a picture of one of my favorite bare twig plants, American beech (Fagus grandifolia).

I love the beech’s distinctive cigar-shaped leaf buds with tips that look like they could stab you and draw blood.  There are other trees with pointy leaf buds to confuse us.  Serviceberry (Amelanchier spp.) has them, but the buds are not as long, they are not uniform in color 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 scar on Hydrangea quercifolia

Leaf scars, bundle scars, buds and other characteristics: some plants have very noticeable and unique leaf scars.  A leaf scar is the spot 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 arrangement of them.  Here is a picture of oakleaf hydrangea (Hydrangea quercifolia) showing two leaf buds (oppositely arranged) and below the bud on the right is a large leaf scar where you can see the some of the bundle scars (indented dots). Leaf buds themselves can be large, small, scaled, naked, hairy or glabrous; examining them closely reveals lots of details. Also note characteristics like presence of thorns (hawthorn, native crabapples, and non-native pear seedlings), raised dots (lenticels), hair on the twig and buds and anything else that looks distinctive. Taking pictures to look at later is a good approach – I find I usually forget to note something!

Bark: 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.

Virginia sweetspire (Itea virginica)

Old fruit/seeds: also look at remaining fruits/seeds left clinging to the twigs.  Some fruit is in the form of a capsule that may open to release seed, leaving the capsule behind.  Here is a picture the seed capsules of Virginia sweetspire (Itea virginica).  Knowing the form of the fruit might help you distinguish one plant from another.

Bloom and leaf buds of azalea (Rhododendron)

I find the bare twigs of woody plants to be every bit as interesting as the leaves and flowers. Many leaf and flower buds are beautiful and intricate in their own way. Now is a good time to study and appreciate them.

Hamamelis virginiana leaf bud

This native azalea’s colorful imbricate scales is one example of the detail that can be found; yet the naked bud (no scales here, this is the actual leaf that will expand) of this witchhazel (Hamamelis virginiana) is amazing as well.

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, examining the twigs and winter features to get familiar with the concept of winter identification.

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