White birch

(sometimes called paper birch)
Betula papyrifera
Family:Betulaceae
(the birch variety represents the largest genus in this family)
Livin'_as_a_birch.mp3 I Podcast Script

The birch tree at Davis High Want a closer look??	The birch tree's somewhat aged bark Want a closer look??
The tree's distinct leaves Want a closer look??	The tree's reproductive parts === === ===The female catkin ............The male catkin=== Want a closer look at both??

Monocot or Dicot:

• Definitely a dicot
• Has secondary growth, woody stem, major indicators of a dicot plant

Size:

• "...as a rule from forty to fifty feet high, though exceptionally growing to eighty feet, with a trunk seldom exceeding a foot in diameter..." (http://www.2020site.org/trees/birch.html)

Identifying Features:

• Bark- brown during first 5 or so years (making it hard to identify from other types of trees early on)
  • In older age-turns silver-white, dark, horizontal lenticels appear, easier to peel
  • The characteristic peeling bark of the birch is probably the most widely known way of identifiying this tree
  • The birch tree's defining characteristic, its conspicuous flaking bark, "... is produced by the formation of alternate layers of larger and smaller cells in the "periderm," or outer bark, of which the larger are the more readily ruptured under the influence of variations in the degree of atmospheric moisture" (http://www.2020site.org/trees/birch.html)
• Leaves-pinnate veined (meaning veins shoot out from main midrib as opposed to all being parallel as is true in monocots)
  • Described as being teethed-a reference to their rough, jagged edges
• Lenticels- the "breathing-holes" for the bark
  • Allow for diffusion of oxygen into and out of the bark as tree ages (bark cells will die without the necessary amount of oxygen)
  • Take place stomata occupied in younger epidermis as tree grows older
  • Grow progressively wider as tree ages and increases its trunk diameter
• Buds- lateral and alternate growing-want a really good explanation of different bud (and leaf) arrangements??
• Seeds-unique winged shape is practical (see under Special Adaptations) as well as aestehtically pleasing

Location/Habitat:

• Usually found in temperate (usually deciduous) or boreal biomes, meaning that it is somewhat out of place in a hotter climate like Davis and the Central Valley
• Most commonly found in the Pacific Northwest, sporadically in the Northeast, much of Canada and the less harsh regions of Alaska
• Major part of the ecosystem
  • Deer and moose eat the tree's twigs
  • Beavers and porcupines love to eat the inner bark
  • Rodents and birds like the seeds stored inside the catkins
• As long as it is in the right climate, a white birch can grow well in almost any soil type as long as it is receiving an adequate amount of water
  • For a birch to be well hydrated, it needs to be in moist, but not too wet, soil
  • Studies have shown that birches do VERY badly in soil that is too dry, so hopefully the DHS janitors/gardeners/custodians have been giving the birch at Davis High enough water or else it may not be around much longer

Want to see a map of where the white birch is commonly found in North America??

Flower/Fruit/Reproduction:

• Reproductive part is the catkin-"a spike like inflorescence [,or cluster,] of unisexual flowers. The male catkin may be borne on one tree, the female on another or both on the same tree..." (http://www.ees.adelaide.edu.au/icooper/glossary/c.htm )
• Male Catkins-yellow to brownish, hang down loosely in groups of 2 or 3
  • Lengthen in spring in preparation for release of pollen in May---after release of pollen, disappear, reappear next spring
• Female Catkins-green, sit on branches pointing upwards, much harder than the male variety
  • Form in early spring as well, fertlized by pollen from male catkins in May
  • Close up after fertilization to ensure proper seed development, wind causes release of the catkins' winged seeds in early to late fall, either disintegrate or in some cases are opened up by birds attempting to eat the seeds
• Seeds-begin making seeds at about age 15
  • Produce the best results in terms of viability and number of offspring from age 40 to 70
  • Usually only produce seeds every other year

Water/Sun Requirements:

For optimal growth and maturation-

• Needs moist, cool soil for its root system which is very shallow and therefore susceptible to drought, also needs sufficient water because of this
• Coupled with the cool soil, ideally needs almost complete sunshine throughout the day on its leaves for them to grow well
• Difficult combination to achieve

Special Adaptations:

• Water resistant bark
• Built in insulation as tree grows, builds tough cork layers that make it very difficult for cold to affect tree
• Winged seeds of male catkin have been at times documented as flying for a couple of miles with the aid of the wind
  • At the very least, usually fly 200-300 feet away from the tree
  • Greatly increases chances of tree's survival as a species, reproduction

Other Interesting (and in many ways equally important) Information:

• "... the best contribution you can make to [a] birch tree's soil and to the long-term viability of [the] tree is the addition of beneficial mycorrhizal fungi" (www.birch-tree.com)
• The birch is the state tree of New Hampshire
• The white birch's species name, papyrifera, comes from the Greek word for paper (papyrus) and is a reference to the tree's unique, paper-like bark
• The white birch was used extensively by the American Indians to cover their canoes because of the water-resistant properties of the tree's bark
• The birch is also an important sucession tree; birch trees are always some of the first plants to appear after major devastation of a forest (caused by fires, logging etc.)
• In many cultures, the birch has a spiritual significance of purity and rebirth, partially related to its status as a sucession tree
• Some birch trees are cut down in their formative years to make a somewhat popular alcoholic drink known as birch beer
• Are relative short-lived plants compared to other trees, mostly because of their status as a pioneer species--expected to come into a burned or devastated area and start new growth cycle, living up to an absolute maximum of 100 years (and in a domestic climate, especially in Davis where the conditions are definitely not ideal, its life span is under half of its normal expectancy)
• The birch leafminer is a major pest of the birch tree, but for the most part does not do any fatal damage to the birch tree when it attacks it (unless the birch is already not very healthy to begin with, and in that case, it is possible for the leafminer to cause its demise). In fact, the reason birch's are treated for this pest is almost purely because of aesthetic reasons, as humans believe the leafminer detracts from the overall beauty and physical appearance of the tree (the leafminer is characterized by leaving light-colored blotches on the leaves of the birch).

Can you find me at Davis High?

Look to the four corners of campus
Look far and wide
There is only one of me
And I know where to hide

My bark gives me away
I am in plain sight
I was young once
But now I am white

If you come from the east
Then you see me daily
I sit there quietly
As you park your Mercedes

Reference Sources/Links:

Betula papyrifera- nice in-depth descriptions of the white birch, its history etc.
Coombes, Allen J. Trees. New York: Dorling Kindersly, Inc.,1992. p.122.
Ecological Impact of Birch Trees in Scotland-general information about all birches
Ecotravel- wealth of information about the multitude uses of the birch tree
Iowa State University-documentation of all of the plants on the campus, similar in many ways (though of course much more in depth) to the goal of this project
Penn State-good information on birch leafminer, bronze borer-two major pests of the birch tree
Taxonomy of all Flora and Fauna in North America-very detailed descritpions of every aspect of almost every type of plant, amazing amount of data, somewhat boring to read but a very good resource (white birch is under volume 3-Betulaceae)
UC Berkeley-good explanation of what distinguishes monocot from dicot, plethora of examples
United States Department of Agriculture-focus on maintenance of birch trees, sun/water requirements, chart on page that is good source of information for all types of birch, very user-friendly
U.S. Forest Service-good pictures of habitat, location, descriptions of ideal soil, topographic conditions specific to the white birch


This page created by Kenny D. 2007

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