Betula populifolia

Taxobox
name = Gray Birch


image_width = 240px
image_caption = Gray Birches in winter
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Fagales
familia = Betulaceae
genus = "Betula"
subgenus = "Betula"
species = "B. populifolia"
binomial = "Betula populifolia"
binomial_authority = Marsh.

"Betula populifolia" (Gray Birch) is a deciduous tree native to North America. It ranges from southeastern Ontario east to Nova Scotia, and south to Pennsylvania and New Jersey. It also has disjunct populations in Indiana, Virginia, and North Carolina. It prefers poor, dry upland soils, but is also found in moist mixed woodlands. It is a common pioneer species on abandoned fields and burned areas, but is short-lived.

It grows quickly to7 to 9 m tall and 0.3 m trunk diameter, with an irregular open crown of slender branches. The tree often has multiple trunks branching off of an old stump. The leaves are 5-7.5 cm long by 4-6 cm wide, alternately arranged, ovate, and tapering to an elongated tip. They are dark green and glabrous above and paler below, with a coarsely serrated margin. The bark is chalky to grayish white with black triangular patches where branch meets trunk. It is smooth and thin but does not readily exfoliate. The flowers are wind-pollinated catkins 5-8 cm long, the male catkins pendulous and the female catkins erect. The fruit, maturing in autumn, is composed of many tiny winged seeds packed between the catkin bracts.

Like other North American birches, Gray Birch is highly resistant to the Bronze birch borer ("Agrilus anxius"). The leaves of the Gray Birch serve as food for various Lepidoptera however; see List of Lepidoptera that feed on birches. The wood is flexible and is used for spools and firewood.

References

* Little, Elbert L. "National Audubon Society Field Guide to North American Trees: Eastern Region". New York: Alfred A. Knopf, Inc., 1980. ISBN 0-394-50760-6.

External links

* [http://www.hort.uconn.edu/plants/b/betpop/betpop1.html University of Connecticut Plant Database]
* [http://hort.ifas.ufl.edu/trees/BETPOPA.pdf University of Florida Environmental Horticulture]
* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500261 Flora of North America, profile and
]
* [http://www.cnr.vt.edu/dendro/dendrology/syllabus/factsheet.cfm?ID=16 VT Dendrology]