HEMLOCK (Tsuga canadensis)

Distinguishing characters: Its leaves are arranged in flat layers, giving a flat, horizontal and graceful appearance to the whole branch. The individual leaves are dark green above, lighter colored below, and are marked by two white lines on the underside.
Hemlock Needs and Cones
The leaves are arranged on little stalks, a characteristic that does not appear in the other evergreen trees.

Form and size: A large tree with a broad-based pyramidal head, and a trunk conspicuously tapering toward the apex. The branches extend almost to the ground.
Hemlock Trees
Range: The hemlock is a northern tree, growing in Canada and the United States.
Hemlock Range
Soil and location: Grows on all sorts of soils, in the deepest woods as well as on high mountain slopes.

Enemies: None of importance.
Woolly Adelgid Infestation
Value for planting: The hemlock makes an excellent hedge because it retains its lowest branches and will stand shearing. In this respect it is preferable to the spruce. It makes a fair tree for the lawn and is especially desirable for underplanting in woodlands, where the shade from the surrounding trees is heavy. In this respect it is like the beech.

Commercial value: The wood is soft, brittle, and coarse-grained, and is therefore used mainly for coarse lumber. Its bark is so rich in tannin that it forms one of the chief commercial products of the tree.
Hemlock Bark
Other characters: The fruit is a small cone about ¾ of an inch long, which generally hangs on the tree all winter.
Hemlock Cones

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 involves the coniferous eastern or Canadian hemlock tree, which has leaves arranged on little stalks and marked by two white lines on the underside. The hemlock retains its lowest branches and withstands shearing, making it suitable for hedges. The bark of the Hemlock produces tannins for commercial purposes. The scientific (Latinized) name of the hemlock is Tsuga canadensis.

Vocabulary

Stalk: The stalk of a leaf, attaching the blade to the stem.
Hedge: A thicket of bushes or other shrubbery, especially one planted as a fence between two portions of land, or to separate the parts of a garden.
Tannin: A yellow or brown bitter-tasting compound present in some plants.
Tannery: A place where people tan hides (animal skins) to make leather.

Concepts

TANNINS

  1. Tannins are yellow or brown bitter-tasting compounds commonly present in the bark of many coniferous trees, wood, leaves, buds, stems, fruits, seeds, and roots.
  2. Tannins help to protect plants from infections.
  3. Tannins are found in apples, red grapes, tea, coffee, almonds, cinnamon, cloves, pomegranates, red beans, walnuts, chocolate, red wine, or blueberries.
  4. Tannins tend to produce a dry, puckery sensation in your mouth.
  5. Tannin from decaying vegetation can turn water reddish, such as the Oparara River in New Zealand.
  6. See workers in Prattsville NY peel hemlock bark to obtain tannin for commercial purposes.
  7. Commercial uses for tannin include 'tanning' or converting animal skins into leather. See a traditional tannery in Morocco, Africa.
  8. Today, synthetic tannin can be created in laboratories, reducing the demand for vegetable tannins derived from vegetable matter.

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

  • Embark upon a nature walk, and search for items containing tannins, such as the bark of coniferous trees, wood, leaves, buds, stems, fruits (acorns), seeds, and roots.
  • When you return, search for items containing tannins around your home, such as apples, red grapes, tea, coffee, almonds, cinnamon, cloves, pomegranates, red beans, walnuts, chocolate, red wine, or blueberries.
  • Make observations and gather data.
  • Use the gathered information to create the field book entry.

Activity 4: Complete a Field Book Entry   

After your nature walk, complete page 40 in 'Science Field Book for Fourth Grade.'

Review

Question 1

Where can you find tannins out in the woods?
1 / 5

Answer 1

Tannins are found in the bark of many coniferous trees, wood, leaves, buds, stems, fruits, seeds, and roots.
1 / 5

Question 2

Name some foods around your house that have tannins.
2 / 5

Answer 2

Answers might include apples, red grapes, tea, coffee, almonds, cinnamon, cloves, pomegranates, red beans, walnuts, chocolate, red wine, or blueberries.
2 / 5

Question 3

Describe the mouth feel of tannins.
3 / 5

Answer 3

Tannins have a dry, puckery mouth feel.
3 / 5

Question 4

How are tannins used in a tannery?
4 / 5

Answer 4

Tannins are used in a tannery to turn animal skins into leather.
4 / 5

Question 5

What is the difference between synthetic tannins and vegetable tannins?
5 / 5

Answer 5

Synthetic tannins are made in a laboratory while vegetable tannins are extracted from vegetable matter.
5 / 5

  1. Where can you find tannins out in the woods? Tannins are found in the bark of many coniferous trees, wood, leaves, buds, stems, fruits, seeds, and roots.
  2. Name some foods around your house that have tannins. Answers might include apples, red grapes, tea, coffee, almonds, cinnamon, cloves, pomegranates, red beans, walnuts, chocolate, red wine, or blueberries.
  3. Describe the mouth feel of tannins. Tannins have a dry, puckery mouth feel.
  4. How are tannins used in a tannery? Tannins are used in a tannery to turn animal skins into leather.
  5. What is the difference between synthetic tannins and vegetable tannins? Synthetic tannins are made in a laboratory while vegetable tannins are extracted from vegetable matter.

References

  1. 'Studies of Trees' by Jacob Joshua Levison. gutenberg.org/ebooks/16116. n.p.
  2. 'Tsuga canadensis.' Wikipedia. Wikipedia.org. n.p.
  3. 'Tannin.' Wikipedia. Wikipedia.org. n.p.
  4. 'Tannin in Plastic Container by Simon A. Eugster (CC BY 3.0)' Wikimedia Commons. en.wikipedia.org/wiki/File:Tannin_in_Plastic_container.jpeg. n.p.