Buds

I’ve met people who thought that buds appeared in spring just before the leaves came out but no, buds actually form in late summer, when trees begin storing reserves to help them get through winter. The period is called lignification and it happens when trees stop their active growth cycle. One of the ways to identify trees and shrubs in winter is by their buds. The size and placement of buds as well as the number of bud scales (cataphylls) can all help with identification. Bud scales are modified leaves that cover and protect the bud through winter. Some buds can have several, some have two, some just one scale called a cap, and some buds have none at all. Buds that have several scales are called imbricate and have scales that overlap like shingles. I’m starting this post with some unusual trees that aren’t often seen in this area, and the bud shown above is a sweet gum bud. It is a good example of an imbricate bud. It is also a good example of a rarity here.

Sweet gum trees (Liquidambar styraciflua) are easily identified by their unusual seed pods, above, and by the large size of their buds, which can be green, red or orange. I’ve read that Native Americans used the hardened resin from these trees for chewing gum. The resin was also used in a tea to calm the nerves and, when powdered and mixed with shavings from the tree, was used as incense by the Maya. The resin is said to look like liquid amber, and that’s where the first part of the scientific name, Liquidambar comes from.

Another tree you’ll have a hard time finding in this area is the European copper beech (Fagus sylvatica purpurea.) I’ve looked at its buds before in March and maybe they were swelling up to prepare for bud break, but they seemed bigger than those on our native trees. This year in January they really don’t look much different than our native beech buds. Long and pointed, they are a different shape than the sweet gum bud we saw but are still imbricate buds because of their shingle like, overlapping bud scales. They’ll open with maroon foliage, which over time will become a beautiful bronze / purple.

I love the bark on this old beech tree. It reminded me of an elephant’s skin. This tree lives on the grounds of the local college and there is another in Dublin, but otherwise I don’t know of any other European beeches in this area.

Tibetan cherry (Prunus serrula Tibetica) is another tree you might have a hard time finding but if you had studied your buds, you would recognize these big, shiny red buds as more imbricate buds. A gummy resin often fills any spaces between the scales and makes the bud waterproof. If water ever reached the bud and froze it could kill or damage it, so nature found a way to prevent that from happening. The shape of many imbricate buds also ensures that water will run off, rather than stay on the bud. Bud scales also help prevent moisture loss. These buds are very pretty, in my opinion.

The bark of a Tibetan cherry is very interesting. It is also called the paper bark cherry because of the way its bark peels as it ages, much like a birch. It is used as an ornamental tree as much for its bark as for its flowers, which are similar in shape and size to other ornamental cherries. The mahogany bark has very long, closely spaced lenticels that give it an unusual appearance. Lenticels are corky pores that allow gases like oxygen to reach the living cells of the bark. Without enough oxygen bark can die, so it “breathes.”

The most unusual tree bud to appear in this post is that of the ginkgo, which I find at the local grocery store, of all places. The short shoots bear terminal buds that are small at less than an eighth of an inch, with room for just two overlapping scales. A bud with only two overlapping scales is called two ranked. You can see how the terminal bud and many leaf scars are crowded together. Ginkgo is considered a “fossil tree” that has been on earth for millions of years. It is also considered the oldest living seed plant. It is said to be capable of living several hundred years, and there are trees in China that are thought to be at least 400 years old.

Buds with two scales that meet but do not overlap are called valvate buds, and a good example of a valvate bud can be found on nannyberry shrubs (Viburnum lentago). Though the scales in the photo do happen to overlap somewhat normally they would not, so they are still considered valvate. Nannyberry is one of our few native viburnums with edible fruit. They can get quite tall, almost the size of a small tree. According to the book The Origins of English Words “nannyberry” is also called sheep berry and that name comes from its fruit, which is said to resemble sheep droppings. The nanny part of the name comes from the nanny goat. Squirrels and birds are said to eat the fruit but I see huge numbers of them still on the bushes well into winter.

Cornelian cherry buds (Cornus mas) are also good examples of valvate buds. In the spring when the plant begins to take up water through its roots the buds swell and the two scales part to let the bud grow. What confuses me about this shrub is how the two outer scales never seem to be completely closed. It doesn’t seem to matter though because they always flower beautifully. Some bud scales like these are hairy and some are covered with sticky resin that further protects the bud. Cornelian cherry is an ornamental flowering shrub related to dogwoods. It blooms in early spring (in March) with clusters of blossoms that have small, bright yellow bracts.

One bud scale covering a bud is called a cap, and magnolia bud scales are good examples of that. Magnolia flower buds are described as “densely pubescent, single-scaled, terminal flower buds” and that’s what we see here. The hairy single scale will fall off when the bud inside has swollen to the point of blossoming. Once the plant flowers the ground under it will be littered with these hairy caps for a short time, so if you’d like to see one up close that’s the time to look.

I was lucky to find a seed pod on the magnolia that I looked at but unfortunately it was quite dry. I’d like to find a fresh one because I’ve read that they’re full of bright red seeds. I’ll look for one this spring to show you.

Big, black and pointed mountain ash buds (Sorbus americana) fooled me into thinking they had a single cap like bud scale at first, but they actually have several overlapping scales which are quite sticky. I finally got a photo that shows this. You have to look closely at buds to see what is really going on, so it helps to have a loupe or a macro lens.

The terminal buds on a Colorado blue spruce (Picea pungens) are oval shaped and imbricate with many bud scales. Sometimes the scales pull back from the bud (reflex) as these did, creating what look like tiny green flowers. In a way they remind me of the male flowers on a haircap moss, but of course they’re much bigger.

Here is a look at the side of the bud in the previous photo. Evergreen buds can be very sticky, but I’ve noticed that much more sap or resin flow occurs on warm days. On a cold day in January these buds were hardly sticky at all. You can also see the rows of whiteish breathing pores (stomata) on some of the needles in this shot. Carbon dioxide, oxygen, and water vapor enter and exit the tree through these tiny openings. There are many millions of them on a single tree.

If you see that some of the branches on your Colorado blue spruce are a bit deformed like those seen in the above photo your tree has the Eastern spruce gall adelgid living on it. They cause crab claw like galls but don’t do any real harm to the tree. I’ve had them on a tree in my yard for years now and it is still as healthy as the day I planted it. By the way, a blue spruce can be green.

If I had to choose a favorite tree bud the flower buds of the red maple (Acer rubrum) would have to be at the top of the list. They’re very beautiful but more than that, they are one of my first signals that spring has finally come. It doesn’t matter what the calendar says, when I see red maple flowers, I know winter is over. Of course sometimes they get a little over anxious and will get frost bitten, but more often than not they’re a reliable indicator. Each small flower bud has four pairs of bud scales.

Sugar maple terminal buds (Acer saccharum) appear on the end or terminus of a branch. The larger, pointed, very scaly bud is flanked by lateral buds on either side. The lateral buds are usually smaller than the terminal bud and the twigs and buds are brown rather than red like silver or red maples. These buds have imbricate bud scales and they show the whitish, sticky resin that “glues” one scale to another.

Norway maple (Acer platanoides) buds are also imbricate but instead of sticky resin on the edges of its bud scales they have a fringe of fine hairs which help shed water. These buds are relatively large and easy to study using a hand lens, so they’re perfect for children in the field.

Buds that have no bud scales but are very hairy like those seen on witch hazel (Hamamelis virginiana,) are called naked buds. The hairs take the place of bud scales when it comes to protecting the bud and it works well. Other naked buds are found on staghorn sumacs (Rhus typhina) and the native viburnum called hobblebush (Viburnum lantanoides).

Witch hazel flower buds are also very hairy, but rounder than its leaf buds. It won’t be long before the yellow or orange strap like flower petals appear on the spring witch hazels. It’s something I’m impatiently looking forward to.

I know that not everyone gets as excited over buds as I do but I also know that there are children who read these posts so I often have them in mind when I do a post like this one. I hope something like a post on buds might help jump start a child’s interest in nature. They aren’t that complicated and hopefully bud scale terminology won’t seem too intimidating.

If you are interested in learning about tree and shrub buds, start with one in your own yard that you are sure of, like a maple tree or even your rhododendron, and then branch out to those you don’t know well. The following information might help to get you started:

A bud scale is made up of modified leaves or stipules that cover and protect the bud in winter. Usually the number of bud scales surrounding a bud will help identify a tree or shrub.

Imbricate bud: A bud with numerous scales that overlap each other like shingles.

Valvate bud: A bud with two or three scales that do not overlap.

Two Ranked Bud: A bud with two scales that do overlap.

Caplike bud: A bud with a single scale that comes off in the spring.

Naked bud: A bud with no scales.

If you find that you have the itch to learn even more about buds and trees, this little book is for you. I’ve had my copy since I was a teen but it’s still in print. It is very helpful and easy to understand.

Must we always teach our children with books? Let them look at the stars and the mountains above. Let them look at the waters and the trees and flowers on Earth. Then they will begin to think, and to think is the beginning of a real education.  ~David Polis

Thanks for stopping in.