Arboretum volunteer and donor Janet James is familiar to readers through the series of articles she has written and that we have featured in our newsletter over the past year. Janet’s photographic efforts to systematically record the summer form, bark, leaf, leaf scar, bud, flower, fruit, fall leaf color, and winter form of the native trees and shrubs in the Walk Across Kentucky (WAKY) Native Plant Collection, and then to tell us about her journey “exploring The Arboretum,” are not only enormously beneficial to help build out our database of plant characteristics, but (we hope you will agree!) also very informative to read. We are pleased to share here Janet’s last article about winter buds and we hope you enjoy it!

In her visually stunning coffee table-size book Seeing Trees, subtitled Discover the Extraordinary Secrets of Everyday Trees, author Nancy Ross Hugo suggests what may seem like an outrageous claim. She presents the idea that because our native trees are living, breathing entities in constant action and change, “tree watching” (her term) can be as fascinating as bird watching! Although I expect skepticism from some, I agree with her that making the effort to look intimately at tree features like leaves, bark, flowers, buds, twigs, leaf scars, and seed structures is indeed rewarding for nature enthusiasts who then discover the engineering, construction, designs, and energy of trees.

I find this time of the year perfect for viewing one of Hugo’s secrets of trees: winter buds. A walk around The Arboretum reveals them everywhere now. They mature throughout the summer and fall and contain the coming year’s leaves, flowers, and twig extensions. On pause during this season, the buds rest before they swell and begin popping open in March. One delightful, helpful aspect is that each tree species bears unique, beautiful buds making identification rather simple for some trees and shrubs. In the absence of leaves, one can walk up to a native tree in a winter woods, neighborhood, or backyard; check out a bud on a twig; and, in some cases, name it.

The photos above and below are a sampling of winter tree buds along with ones depicting how they appear just as they open in spring, spilling forth their amazing contents. Each species’ buds are distinct in color, shape, texture, and size. I studied the buds as I photographed them for The Arboretum Explorer database and along the way found sources to acquire a little useful bud terminology. Lateral buds are ones along the sides of a twig while terminal buds are found at the end on the tip. 

In Kentucky, buds need insulation for protection during our winter weather, and I’ve observed how trees have devised excellent ways to accomplish that. Almost all have bud scales (modified leaves) covering them. When at least three or usually more scales overlap like roof shingles, they are called imbricate. The species shown below have imbricate bud scales.

I noticed that American basswood and tulip trees have the unusual number of two scales per bud. In the following photos, the two reddish basswood scales overlap, but the two tulip tree scales resemble a duck’s bill, called a valvate bud.

The next photos show a few quirky tree species having only one scale per bud which wraps around it like a blanket. 

It surprised me to learn a couple of tree species forgo typical bud scales and have what is called naked buds! In this case, waterproof leaves or dense plant hairs do the trick to protect them instead.

About 20 of the approximately 120 Kentucky native tree species are oaks in the genus Quercus. Because their multiple, imbricate, pointed terminal buds form in a cluster at the end of a twig, identifying them as oaks is not difficult. Determining a specific oak species in winter may require additional clues, though. But I take pleasure in just knowing a particular tree I’m standing by is one of our mighty oaks that harbor and provide sustenance for numerous important fauna.

If this article entices you to take a close look at winter tree buds, consider The Arboretum as an ideal location to enjoy doing so. Almost all Kentucky native tree species are represented in the collection and tagged with their Latin and common names. Arboretum Explorer, a publicly accessible, online mobile platform is the database for them. Any GPS-enabled device such as a cellphone will lead a visitor to find exact species on the grounds by going online to Arboretum Explorer. The paved and mulched trails that crisscross the property provide pathways for a walk in fresh, brisk winter air and the pursuit of the “secrets of trees.”

Ten Tree Species Easily Identified by Winter Buds:

1. American beech (Fagus grandifolia): a long, narrow, rusty brown, dagger-shaped bud
2. Tulip poplar or tulip tree (Liriodendron tulipifera): a duck bill-shaped bud  
3. Bitternut hickory (Carya cordiformis): an unmistakable, vibrant yellow bud
4. Basswood (Tilia americana): a red bud with only two bud scales 
5. Red maple (Acer rubrum): red, clustered, soccer ball-shaped buds
6. Sweetgum (Liquidambar styraciflua): a large, shiny, reddish brown, imbricate terminal bud
7. Pawpaw (Asimina triloba): a brown, hairy, naked terminal bud, shaped like a bent finger 
8. Oaks (Quercus spp.): pointed, imbricate, and clustered terminal buds
9. Sassafras (Sassafras albidum): a medium-sized, imbricate, bright green bud
10. Bigleaf magnolia (Magnolia macrophylla): a very large, light green, single bud scale bud covered in soft, white matted hairs

(All but sassafras are pictured above.)