Betula pumila (Bog Birch, Dwarf Birch, Bouleau Nain)


Botanical Information

FamilyBetulaceae
GenusBetula
Speciespumila
CategoryWoody
TypeShrub (deciduous)
ReferencesDirr, Michael, A. (2009). Manual of Woody Landscape Plants. (6th ed.) Illinois: Stipes Publishing L.L.C. Hillier, Edwin. (1973). Hillier’s Manual of Trees and Shrubs. (1st ed.) New Jersey: A.S. Barnes & co., Inc.
OriginNative to North America. Found throughout Southern Canada and the Northern United States.
Ethnobotanical Uses
Disclaimer
Native American cultures used a solution derived from Betula pumila flowers as a gynecological aid for recovery post-childbirth. The flowers were also burned and inhaled as a respiratory aid to treat build up of mucous by Ojibwe tribes. Small woody branches were used as ribbing in Native basket weaving.

Details

USDA Hardiness Zone2 - 8
USDA Hardiness Ref.
Canadian Hardiness Zone3b - 9
Canada Hardiness Ref.
RHS Hardiness ZoneH7
RHS Hardiness Ref.
Temperature (°C)-20
Temperature (°F)-4
Height2-3.5 m
Spread4 m
GrowthFast
Flowering PeriodMay, June

Description and Growing Information

General DescriptionThis irregular shrub has been placed on the IUCN Red List as least concern. It is one of few shrubs found in the Betulaceae family.
ID CharacteristicBetula pumila can be distinguished from other shrubs in the genus by its highly pinnate venation in the leaves.
LandscapeIt could be used as a specimen plant due to its unusual leaf-shape.
PropagationPropagates through seeds. Must be planted in late autumn to stratify for at least 3 months during the winter. Seeds are to be planted before full maturity is reached (when they will turn from pale green to light brown). Seeds are dispersed broadly with very little covering and can even be sown atop snow. Moisture is more important than low temperature and seeds must be kept moist in order to germinate. Seeds must be kept at 1-3% moisture and at a temperature of 2-5°C if stored.
CultivationPrefers moist acidic soil. Can be grown in full sun to partial shade. Tolerant of cold winter temperatures.
PestsVulnerable to canker, dieback, leaf blister, leaf spot and powdery mildew.
Notable SpecimensThe University of Guelph Arboretum located East of the university campus in Guelph, Ontario.
HabitatLow-lying marshes, swamps and lake shores.
Bark/Stem DescriptionDark brown colour with a reddish colour at the terminal ends of branches.
Flower/Leaf Bud DescriptionBuds appear in late winter and are a source of winter food for birds and deer.
Leaf DescriptionSmall, obovate shape with serrate edges (2-3 cm long and 1-2 cm wide). They appear alternately in a simple arrangement and have a pinnate venation pattern.
Flower DescriptionCylindric and erect infructescences, 0.8-1.5 x 0.5-1 cm, producing fruit in autumn.
Fruit DescriptionFemale catkins develop ovoid shaped nutlets in groups of 3 with the central scale being slightly larger than the latereal ones.
Colour DescriptionThe leaves are a mild green colour and turn to light yellow in autumn. Catkins are light to moderate green and turn to light brown at maturity. Bark is dark brown and are reddish-brown at the tip of the branch.
Texture DescriptionMedium texture. Branch and petiole texture ranges from glabrous to pubescent. Leaves are completely glabrous.

Photographs