Betula uber (Virginia Roundleaf Birch)


Michael's Opinion

A scarce tree that would make for a very nice background filler, It can be easily identified between Betula species by the round leaf shape, as opposed to B. lenta and similar species with a more ovulate leaf shape. Additionally, stronger conservation efforts should be brought forward to avoid the extinction of this species.

Botanical Information

FamilyBetulaceae
GenusBetula
Speciesuber
CategoryWoody
TypeTree (deciduous)
OriginCan only be found naturally growing near banks of creeks in Southwestern Virginia in Smyth County. First described in 1904, however was thought to be extinct for much of the mid-1900s until its rediscovery in 1975. In 1998 the IUCN red-listed it as critically endangered.

Details

USDA Hardiness Zone5a
USDA Hardiness Ref.
Canadian Hardiness Zone5a - 5b
Canada Hardiness Ref.
RHS Hardiness ZoneH7
RHS Hardiness Ref.
Temperature (°C)(-29) - (-26)
Temperature (°F)(-20) - (-15)
Height4.5 - 10 m
Spread3 - 5 m
GrowthMedium
Flowering PeriodApril, May

Description and Growing Information

General DescriptionKnown only from a small population in Smyth County Virginia, this smaller, compact tree has rounded leaves, standing as a simple way to identify it apart from other birch species. In the autumn it protrudes a yellow colour with an aroma of wintergreen when the bark is bruised.
ID CharacteristicA small tree with round leaves that are slightly notched at the base, with a compact crown, the trunk is narrow with slender spreading branches and produces a wintergreen aroma from the bark when bruised.
ShapeA small slender trunk with a compact oval crown.
LandscapeThis would make for a brilliant park or garden tree to display its beautiful autumn colour, although not easily obtained due to its rarity.
PropagationMicropropagation of dormant buds supplied with organic nutrients saw shoots with 3-4 leaves that were 2-3 cm tall in four weeks. In high humidity conditions root development occurs after 4-6 weeks.
CultivationFor the best chance of longevity, plant in moist, well-drained soils near waterways. Cuttings can be propagated and then transplanted in moist, slightly acidic soil with good drainage. Natural germination of seeds yields poor results, with the majority of seeds unable to compete with surrounding new growth. Seeds require cold stratification for 60 days and will have the most success with human involvement, being placed in ideal conditions.
PestsTolerant to heat, and insect bores.
Notable SpecimensJefferson National Forest, Virginia, National Arboretum in Washington.
HabitatCan be found by banks of streamlets in mixed hardwood forests, under the shade of taller trees, and on slopes where the soil is moist.
Bark/Stem DescriptionThe bark is grey, thin and smooth, with horizontal lentils which produce a wintergreen aroma when agitated. The twigs are brown, slender and hairless. The stem is hairy and short measuring 1-3 cm.
Flower/Leaf Bud DescriptionTheir buds are pointed and small at a size of 5 mm with smooth scales around. Red to brown in colour.
Leaf DescriptionDark green top and paler on the underside, round to slightly oval with a heart-shaped base, measuring 4-6 cm long and 3-5 cm wide. Irregular saw-tooth serration, stem covered in tiny hairs.
Flower DescriptionNearly smooth catkins that are 1.7-2.8 cm in length, long scales with three spread-out lobes. The small yellow flowers occur from late April to early May, when leaves begin to emerge from winterized buds. Male and female parts are separately produced on the same tree.
Fruit DescriptionCones that are 1.2 cm long, upright and almost stalkless at the base. 3 samaras (dark brown nutlets) emerge with a size of 1.7-2.0 mm.
Colour DescriptionThe bark is grey with horizontal lines. In the spring the male flowers are a pale yellow, while the female is greenish. The leaves are dark-green in summer changing to yellow in autumn.
Texture DescriptionSmooth bark with horizontal lines, the leaf is softly serrated and smooth on top, with a subtle texture on the underside. Catkins have a soft cone feel.

Photographs