Ranger Steve’s Nature Niche
By Ranger Steve Mueller
Winter tree and shrub buds have distinctive character. They are recognizable by features like being fat, short, tall, scaly, fuzzy or with varied color. Twigs bear terminal and lateral buds. Often winter buds are larger or swollen indicating they are flower buds instead of new leaf or stem buds.
Bud scales hide inner layers protecting delicate tissues during the cold season. Some common shrubs like witch-hazel (pictured at right) and poison ivy buds are not covered with protective scales.
The tissues for new leaf, stem, and flowers are produced during the previous year’s growing season. That makes them vulnerable to frost and abrasion damage as well as being harvested by wildlife as winter food. Besides being protected by scales, bud tissues are mostly devoid of water. Water is minimally maintained in roots to sustain life but stem, branch, and twigs are somewhat dehydrated.
Water expands when it freezes like many of us old timers discovered if we did not promptly bring milk in from below 32ºF temperatures when home delivery was common. Glass bottles would break. This happens with fruit and vegetables that freeze causing cells to burst and ruin food. With little water in bud tissues, the freezing liquid is not present to rupture cell membranes.
Take winter walks from tree to tree or shrub to shrub to enjoy the variety of buds in the neighborhood. I have frequently stated it is not necessary to the learn names but it is more important to discover the wonder and beauty that surrounds us. After observing the diversity, you might want to learn names. Winter is one of the best times to recognize species. Leaves on woody plants vary in shape and can make identification difficult. A major problem with leaves is caused by production by long or short shoots or apical or basal stems. That is a topic for a different Nature Niche but the different stem types create varying leaf shapes and sizes.
Winter buds are more consistent and reliable for identification. There are differences between leaf, stem, and flower buds and variation between lateral and terminal buds is relatively minor.
A terminal bud grows at the tip of a twig. Lateral buds grow at an angle from the stem or might grow at the end of a stem but do not protrude straight and centered from the end. They angle to the side and is called a false terminal bud. Look at an elm’s false terminal bud at the end of a branch. Maples provide a good example for terminal buds and have lateral buds growing outward to the side at the base of the terminal bud.
Silver or red maples in our yards have rounded buds and sugar maples have pointed buds. Gently tap the end of a maple bud with your fingertip to notice if it is pointed or rounded. A difference between red and silver maples compared with sugar maple buds is the lateral buds are not as heavily clustered on sugar maples. More flower buds are present on red and silver maples high in the tree and produce a greater quantity of early Spring flowers. Sugar maple flowers bloom about a month later.
Choke cherry buds are dark with a light tan border along the edge of each protective scale. Their buds are pointed. Bitternut hickory is common in our area and like the hazelnut, it does not have bud scales. You can observe the new embryonic leaves that are tightly clumped together as naked exposed leaves all winter. This is best seen with a small magnifying lens called a loop. Willows have a single scale covering embryonic leaves.
Some buds are covered with minute hairs and others are smooth and shiny. Each species has distinctive buds.
About 70 native tree species are known to Michigan and about 130 shrubs. Look at interesting characteristics. When the protective bud scales fall in Spring, they leave bud scale scars where the scales attached to twigs. The distance between bud scale scars helps determine how much a branch grew during the year. Hey bud, enjoy a close look at plant buds.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at [email protected] – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.
Witch Hazel photo by Robert Vidéki, Doronicum Kft., Bugwood.org
Red Maple and Sugar Maple bud Photos by Rob Routledge, Sault College, Bugwood.org
Banner photo Red Maple by Paul Wray, Iowa State University, Bugwood.org