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GRAY OR WHITE BIRCH (Betula populifolia)

Distinguishing characters: The dull-white color of the bark on the trunk and the dark triangular patches below the insertion of the branches distinguish this tree. The bark of the young trunks and branches is reddish-brown in color and glossy. The bark adheres closely to the trunk of the tree and does not peel in loose, shaggy strips, as in the case of the yellow or golden birch. It is marked by small raised horizontal lines which are the lenticels or breathing pores. These lenticels are characteristic of all birch and cherry trees. In addition to the distinction in the color of the bark, an important character which distinguishes the gray birch from all other species of birch, is found in the terminal twigs, which are rough to the touch.
Birch Lenticels (Horizontal Lines)
Form and size: A small tree. Frequently grows in clumps.
Clump of Birches
Range: Eastern United States.
Betula populifolia Range
Soil and location: The gray birch does best in a deep, rich soil, but will also grow in poor soils.

Enemies: The bronze birch borer, a wood-destroying insect, and Polyporus betulinus, a fungus, are its chief enemies.
The Bronze Birch Borer
Value for planting: Its graceful habit and attractive bark gives the tree an important place in ornamental planting. It may be used to advantage with evergreens, and produces a charming effect when planted by itself in clumps.
The Beautiful Birch
Commercial value: The wood is soft and not durable. It is used in the manufacture of small articles and for wood pulp.
Betula populifolia Leaves
Other characters: The fruit is a catkin.
Birch Catkins
Comparisons: The paper birch (Betula papyrifera) is apt to be confused with the gray birch, because both have a white bark. The bark of the paper birch, however, is a clear white and peels off in thin papery layers instead of being close. It very seldom shows any dark triangular markings on the trunk. Its terminal twigs are not rough and its trunk is usually straighter and freer from branches.
The Paper Birch (Betula papyrifera)

Directions

Study the lesson for one week.

Over the week:

  • Read the lesson.
  • Review the synopsis.
  • Recite aloud the vocabulary words and their definitions.
  • Learn the concepts.
  • Complete the enrichment activities.
  • Study the review questions.

Synopsis

This lesson overviews the gray birch. The gray birch grows in clumps and has white bark marred by horizontal lines called lenticels, which serve as the breathing pores of the tree. The gray birch is also called white birch. The scientific (Latinized) name of the gray birch is Betula populifolia.

Vocabulary

Lenticel: One of many raised pores in the stem of a woody plant that allows gas exchange between the atmosphere and the internal tissues.
Clump: A thick group or bunch of trees or plants.
Wood Pulp: A mixture of wood, cellulose, and water that is ground up to make paper.
Catkin: A type of flower cluster (a spike), as in the birch, willow, and poplar.
Photosynthesis: Any process by which plants convert light energy into chemical energy.
Oxygen Gas (O2): Molecular oxygen, a colorless, odorless gas at room temperature.
Carbon Dioxide Gas (CO2): A colorless, odorless gas formed during respiration and combustion and consumed by plants during photosynthesis.

Concepts

LENTICELS

Certain woody plants have pores in their trunks used for breathing.

Trees take in carbon dioxide gas (CO2) and expel oxygen gas (O2).

Birch trees have small raised horizontal lines on their trunks which are the lenticels.

Apples and other types of fruit have lenticel openings on their bottoms.

Plants require the carbon dioxide to generate energy using photosynthesis.

Enrichment

Activity 1: Narrate the Lesson

  • After reading or listening to the lesson, narrate the lesson aloud using your own words.

Activity 2: Study the Lesson Pictures

  • Study the lesson pictures and describe how they relate to the lesson.

Activity 3: Take a Nature Walk

  • Bring a small sketchbook and a specimen collection bag and embark on a nature walk.
  • Search for any type of birch tree. If you cannot find a birch tree, choose another interesting tree to study.
  • Study and sketch the appearance and habitat of the tree.
  • Collect a leaf specimen from the tree.
  • Use the sketch and leaf specimen to create the field book entry.

Activity 4: Complete a Field Book Entry   

After your nature walk, complete page 10 in 'Science Field Book for Fourth Grade.'

Review

Question 1

What are the horizontal dark lines on gray birch trunks?
1 / 4

Answer 1

The horizontal dark lines on gray birch trunks are the lenticels, which the tree uses for breathing.
1 / 4

Question 2

Which gas must trees take in and people breathe out to survive?
2 / 4

Answer 2

Trees must take in carbon dioxide and people must breathe out carbon dioxide.
2 / 4

Question 3

Which gas do trees expel and do people breathe in to survive?
3 / 4

Answer 3

Trees expel oxygen and people breathe in oxygen.
3 / 4

Question 4

What is one very noticeable difference between the trunk of the gray birch and the trunk of the paper birch?
4 / 4

Answer 4

One noticeable difference is that the bark can be easily peeled off the paper birch but not the gray birch.
4 / 4

  1. What are the horizontal dark lines on gray birch trunks? The horizontal dark lines on gray birch trunks are the lenticels, which the tree uses for breathing.
  2. Which gas must trees take in and people breathe out to survive? Trees must take in carbon dioxide and people must breathe out carbon dioxide.
  3. Which gas do trees expel and do people breathe in to survive? Trees expel oxygen and people breathe in oxygen.
  4. What is one very noticeable difference between the trunk of the gray birch and the trunk of the paper birch? One noticeable difference is that the bark can be easily peeled off the paper birch but not the gray birch.

References

  1. 'Studies of Trees' by Jacob Joshua Levison. gutenberg.org/ebooks/16116. n.p.
  2. 'Photosynthesis by At09kg. (CC BY-SA 3.0)' Wikimedia Commons. commons.wikimedia.org/wiki/File:Photosynthesis.gif. n.p.

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