Betula papyrifera

Taxobox
name = "Betula papyrifera"
status = secure

---

image_width = 240px
image_caption = Paper Birch
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Fagales
familia = Betulaceae
genus = "Betula"
subgenus = "Betula"
species = "B. papyrifera"
binomial = "Betula papyrifera"
binomial_authority = Marsh.

"Betula papyrifera" (Paper Birch, also known as American White Birch and Canoe Birch) is a species of birch native to northern North America.

Description

It is a medium-sized deciduous tree reaching 20 m tall (exceptionally to 35 m) with a trunk up to 80 cm diameter. The bark is white, commonly brightly so, flaking in fine horizontal strips, and often with small black marks and scars. In individuals younger than five years the bark appears brown with white lenticels, making the tree much harder to distinguish from other trees. The leaves are alternate, ovate, 5-12 cm long and 4-9 cm broad, with a doubly serrate margin. The leaf buds are conical and small, they are green colored with brown edges. The flowers are wind-pollinated catkins 3-8 cm long growing from the tips of twigs, the fruit matures in the fall. The mature fruit is composed of numerous tiny winged seeds packed between the catkin bracts. They drop between September and spring.

Distribution

"Betula papyrifera" has a wide range. It is found in interior (var. "humilus") and southcentral (var. "kenaica") Alaska and in all provinces and territories of Canada, except Nunavut, as well as the northern continental United States, south to Pennsylvania and Washington, with small isolated populations further south in mountains to North Carolina and Colorado.

Ecology

"Betula papyrifera" is a pioneer species. It needs high nutrients and a lot of sun. The bark is highly weather-resistant. Often, the wood of a downed paper birch will rot away leaving the hollow bark intact. [Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996.] Birch bark is a winter staple food for moose. The nutritional quality is poor, but is important to wintering moose because of its sheer abundance. Although white-tailed deer consider Birch a "secondary-choice food", it is an important dietary component. In Minnesota, white-tailed deer eat considerable amounts of paper birch leaves in the fall. Snowshoe hares browse paper birch seedlings, porcupines feed on the inner bark and mice eat the seeds. The leaves of the Paper Birch serve as food for various Lepidoptera. See List of Lepidoptera that feed on birches.

Conservation

It is considered vulnerable in Indiana, imperiled in Illinois, Virginia, West Virginia and Wyoming, and critically imperiled in Colorado and Tennessee.

Uses

s. In the construction of sod-roofed houses, the bark is used to create a durable waterproof layer. [Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996.]

Culture

"Betula papyrifera" is the Provincial tree of Saskatchewan and the State tree of New Hampshire.

References

External links

* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260 Flora of North America: "Betula papyrifera"]
* [http://www.efloras.org/object_page.aspx?object_id=5753&flora_id=1 Flora of N.Amer- Range
]
*http://www.cnr.vt.edu/DENDRO/dendrology/syllabus/factsheet.cfm?ID=14 (best picture of young bark)
*http://www.fs.fed.us/database/feis/plants/tree/betpap/all.html (most detailed data)
*http://www.rook.org/earl/bwca/nature/trees/betulapap.html (concise outline details)