An online resource based on the award-winning nature guide

Tree Buds

Next Year’s Buds Already Formed

11-7-18 A. beech bud _U1A1228Because tree buds tend to swell and increase greatly in size in the spring, this is often the season when we first notice them and assume that this is when they are produced.  However, if you look in the axils of leaves on any deciduous tree right now, you will see full-size buds that were formed this summer.   These little packages of miniature leaves, branches and sometimes flowers, will remain on trees all winter, tightly closed and often protected from the elements by modified leaves called bud scales.  Come spring, when trees are once again taking up quantities of water, their buds will swell, scales will fall off (leaving bud scale scars), and tiny, pristine leaves or flowers will appear.  (Photo is of American beech, Fagus grandifolia, bud.)

Just a quick reminder that the NC Calendar ordering deadline is November 10th.

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Basic Botany: Bud, Leaf and Branch Arrangement

1-31-18 twigs-1

In winter it is common to use the pattern by which branches and buds are arranged on a deciduous tree as a first, quick clue to the tree’s identity.  There are two large groups of trees, those with alternate and opposite patterns, and a third less common pattern, whorled.  Trees with alternate arrangement have only a single leaf/bud/branch attached at one location (node) on a branch.  Those with opposite arrangement have two leaves/buds/branches attached at a node, opposite one another on either side of the branch.  When more than two leaves/buds/branches arise from a node (rare) this is called a whorled arrangement.

At this time of year, when deciduous trees are bare, you can see the arrangement of buds, branches and leaf scars (where leaves have fallen off) clearly.  Relatively few trees have opposite branching – Maples, Ashes, Dogwoods, and Horse Chestnuts – while a majority have alternate branching.  More characteristics are needed to narrow a tree down to species, but noting its arrangement is an easy and quick way to eliminate certain species.

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Bud Scales

bud scales 147Much of this coming summer’s woody plant growth is contained in embryonic form inside a tree’s buds. Buds contain an undeveloped shoot, leaf, and/or flower. Formed last summer, these buds must survive the freezing and fluctuating temperatures, relatively dry air and the potential insect, bird and fungal damage that may occur during the fall, winter and early spring.

Bud scales, which are small, modified leaves, cover and protect many of these buds. The number of scales, their arrangement, color, presence or absence of hairs or sticky substances are often distinctive. Willows have one visible bud scale (actually two fused into one), whereas pine and fir buds may have anywhere from 100 to 350. The scales on a bud can either be arranged in pairs facing each other edgewise (American Basswood, pictured) or overlapping like shingles (Sugar Maple, pictured). Colors range from the wine-colored bud scales of Striped Maple to the mustard yellow Bitternut Hickory scales. The texture of bud scales has great variation, including the satiny-smooth hairy bud scales of Box Elder (pictured). Many bud scales, such as poplars, are covered by a gummy substance which serves as added protection.

A few trees and shrubs have buds that lack scales. These are referred to as “naked” buds, and often the embryonic leaves are quite hairy. Witch Hazel, Hobblebush and Staghorn Sumac (pictured) are species of woody plants lacking bud scales.

Most buds have multiple scales which, upon falling off when the bud opens, leave a series of horizontally-elongated scars on the surface of the growing stem. By means of these scars one can determine the age of a young branch, since each year’s growth ends in the formation of a terminal bud which produces an additional group of bud scale scars. Continued growth of the branch causes these scars to be indistinguishable after a few years so that the age of older branches cannot be determined by this means.

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Black Cherry – well known to most readers!

black cherry tree silhouette IMG_5114Black Cherry, more than most tree species, often has several identifying features even after it loses its leaves. The buds of Black Cherry have about ten scales, each of which is brown at the tip and green at the base. The bark of young Black Cherry trees is typically smooth, reddish in color and covered with grayish, horizontal lines called lenticels — small openings that allow the passage of gases in and out of the tree. The bark on older Black Cherry trees consists of squarish scales, curved outward at their vertical edges, somewhat resembling burnt potato chips. Black Cherry is one of several trees on which the fungus Apiosporina morbosa causes Black Knot Galls. Lastly, Black Cherry is the primary host for the Eastern Tent Caterpillar moth. These moths encircle Black Cherry branches with their egg masses, and the eggs hatch just as Black Cherry’s leaves emerge from their buds, providing food for the young larvae.

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Red Squirrels & Sugar Maples

2-20-15 red squirrel2 IMG_7851We’re approaching what is often a very stressful time of year for many animals, including red squirrels. In the fall they feed on all kinds of conifer seeds, mushrooms, insects, nuts and the many fruits and berries that are available. They also have caches of cones, which they turn to once there is a scarcity of food elsewhere.

Once these caches are used up, usually by late winter or early spring, red squirrels turn to sugar maples for nutrients. Their timing is perfect, for this is when sap is starting to be drawn up from the roots of trees. Red squirrels are known to harvest this sap by making single bites into the tree with their incisors. These bites go deep enough to tap into the tree’s xylem tissue, which is where the sap is flowing. The puncture causes the sap to flow out of the tree, but the squirrel delays its gratification. It leaves and returns later to lick up the sugary residue that remains on the branch after most of the water has evaporated from the sap.

Not only do red squirrels help themselves to sugar maple sap, but they have developed a taste for the buds, and later in the spring, the flowers, of both red and sugar maples. Red squirrels are not the only culprits – gray squirrels and flying squirrels also make short work of buds and flowers from these trees.

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White Ash Winter I.D.

2-19 white ash leaf scar 007White ash, Fraxinus americana, is relatively easy to identify in winter, between its stout, opposite branches and buds and the corky ridges that form diamond shapes on its bark. There are several species of ashes, however, and one feature that distinguishes White Ash is the shape of its leaf scars (located beneath leaf buds) on well-developed branches. Each leaf scar (left by a leaf that fell off the tree) is round at the bottom and notched at the top, resembling the letter “C” on its side. (No other ash has c-shaped leaf scars.) It is often concave along the upper edge and the lateral buds are located within the curved portion of the leaf scar.

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Northern Red Oak Buds

12-23-14  red oak terminal buds IMG_6865There are approximately 600 species of oaks in the genus Quercus, all of which are in the Beech family. This genus has two subgroups, the red oaks and the white oaks. The leaves of trees in the red oak group have sharply pointed lobes with bristles. The white oak group has leaves with rounded lobes lacking bristles. Although usually there are some leaves on an oak tree that persist well into the winter, it is helpful to be able to identify a species by its buds alone. Oaks tend to have multiple terminal buds. Northern Red Oak’s terminal buds are large, pointed, cone-shaped and covered with reddish-brown, mostly hairless scales that overlap like shingles, with one edge covered and the other edge exposed.

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